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Overcoming the momentum of anachronism: American geologic mapping in a twenty-first century world



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Geological Society of America Special Papers 2013;502; 103-125
P. Kyle House, Ryan Clark and Joe Kopera
twenty-first-century world
Overcoming the momentum of anachronism: American geologic mapping in a
Geological Society of America Special Papers
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The Geological Society of America
Special Paper 502
Overcoming the momentum of anachronism:
American geologic mapping in a twenty-fi rst-century world
P. Kyle House
U.S. Geological Survey, 2255 N. Gemini Drive, Flagstaff, Arizona 86001, USA
Ryan Clark
Arizona Geological Survey, 416 W. Congress Street, Suite 100, Tucson, Arizona 85701, USA
Joe Kopera
Massachusetts Geological Survey, 269 Morrill Science Center, University of Massachusetts,
611 North Pleasant Street, Amherst, Massachusetts 01003, USA
The practice of geologic mapping is undergoing conceptual and methodological
transformation. Profound changes in digital technology in the past 10 yr have potential
to impact all aspects of geologic mapping. The future of geologic mapping as a relevant
scientifi c enterprise depends on widespread adoption of new technology and ideas about
the collection, meaning, and utility of geologic map data. It is critical that the geologic
community redefi ne the primary elements of the traditional paper geologic map and
improve the integration of the practice of making maps in the fi eld and offi ce with the
new ways to record, manage, share, and visualize their underlying data. A modern digital
geologic mapping model will enhance scientifi c discovery, meet elevated expectations of
modern geologic map users, and accommodate inevitable future changes in technology.
Geologic mapping is a cornerstone in the foundation of geo-
logical science. A good geologic map combines complex graphi-
cal representations of an area’s geologic character and history
with an abstraction of the intellectual and technical processes
used to create the map. Portrayals of such complex information
require a fi rm understanding of the science, as well as an artistic
attention to cartographic detail and principles of visual design.
Here, in the early part of the twenty-fi rst century, both the art
and science of geological mapping lie on the cusp of transfor-
mation, wherein the collection and representation of map data
and processes of their interpretation can be created, shared, and
visualized in useful and unexpected new ways.
The potential for transformation is fueled by a revolution
in digital technology that has already wrought tremendous and
global cultural change and will continue to marginalize more
traditional methods of data collection and portrayal. In just the
past 10 yr, developments in geographic information system (GIS)
capa bilities, global positioning system (GPS) technology, inter-
net and data connectivity, and related applications that integrate
them have opened up new possibilities for the collection, man-
agement, analysis, and distribution of geologic map data. The
past few years have seen a remarkable proliferation of power-
ful mobile computing and communication devices coupled with
major growth in online interconnectivity, allowing interaction
and collaboration among millions of users. This phenomenon
has permeated all aspects of culture and has a global impact; for
House, P.K., Clark, R., and Kopera, J., 2013, Overcoming the momentum of anachronism: American geologic mapping in a twenty-fi rst-century world, in Baker,
V.R., ed., Rethinking the Fabric of Geology: Geological Society of America Special Paper 502, p. 103–125, doi:10.1130/2013.2502(05). For permission to copy,
contact © 2013 The Geological Society of America. All rights reserved.
geologists , it has the potential to transform the ways in which
eld data are collected, shared, and analyzed. However, the ex-
tent to which these new possibilities have been embraced by
practicing geologic mappers varies considerably.
Innovative combinations of these digital mapping technolo-
gies have awakened unexpected and great public interest in geo-
spatial concepts and applications. Consequently, rapidly evolving
tools and applications for mapping are being developed that are
raising expectations for types and availability of geospatial scien-
tifi c data sets and related visualization and representation possibil-
ities. These trends are gradually transforming traditional lines of
thinking within geology. As an integrative and deeply geospatial
component of geological inquiry, geologic mapping can be at the
crux of transformation, and geologic mappers have an opportunity
to infl uence the future direction of their practice and to ensure
its continuing and growing relevance to scientifi c discovery and
societal needs.
A geologic map is a textbook on a single sheet of paper … it
refl ects (or should refl ect) … all the important research that has
been done on any geologic topic within its boundaries.
—John McPhee, Annals of the Former World (2000, p. 378)
“Geologic maps are our most important and complete compila-
tion of information about the solid Earth we live on, and we can-
not understand the Earth without them.”
—American Geological Institute, Meeting Challenges
with Geologic Maps (Thomas, 2004, back cover)
Geologic mapping is essential to discovery and rich data
docu mentation in geological science. The quote by McPhee
confi rms feelings among mappers about the hard work that goes
into making maps; it also foreshadows the true potential for digi-
tal geologic maps in the twenty-fi rst century. A map on a sheet
of paper is only a graphic abstraction of the deeper informa-
tion content on which it is based; much more information can be
accessed and displayed in the digital environment. The second
quote further portends the future of geologic mapping wherein
the traditional paper map model is subsumed into a “living”
digi tal map model that is founded on an extensible and updat-
able digital database of scientifi c data, interpretations, and ex-
planations. Modern digital maps can be created, accessed, and
consumed in more contextually meaningful and intuitive ways
than a printed sheet of paper (e.g., Condit, 2010; Whitmeyer
et al., 2010; Shufeldt et al., 2012).
Whether paper or digital, a geologic map is an intellec-
tual commitment to a complex, interrelated series of scientifi c
judgments that are portrayed as a plexus of lines and colored
shapes on a meaningful base. This has traditionally been ex-
pressed on paper, but can now be expressed as an analogous
plexus of shapes in digital form for depiction on any number
of illustrative base layers, on a computer screen, or in printed
form with a prescribed or user-specifi ed symbolic representa-
tion. In any format, it is intended to be a reliable documen-
tation of geologic materials, their structures, distributions, and
stratigraphic relationships—a condensed expression of geo-
logic history. It must be carefully constructed to distill key
geologic information into a meaningful representation that
balances detail and scale. The task of geologic mapping re-
quires competence in a broad array of geologic topics, agile
spatial reasoning skills, and working knowledge of concepts of
cartography and graphic design. The modern task includes the
elements of new geospatial technologies, digital data manage-
ment, and awareness of the diverse arrays of platforms for map
data visualization and distribution.
Some aspects of geologic mapping will remain unchanged
in the transition from paper to digital (traditional to modern). For
example, the basic mechanics of creating a paper or digital map
involve fi eld and offi ce components. No amount of technological
advance will obviate the need for fi eld verifi cation of geologic
interpretation from imagery or older geologic maps, but many
advances will and do increase effi ciencies in planning, perform-
ing, and recording fi eldwork. Finishing a good geologic map in-
volves an iterative process of increasing amounts of offi ce work
and decreasing amounts of fi eldwork and focused “ground-truth-
ing” and data collection. In the offi ce, it can require months of
data compilation and interpretation. Getting the map reviewed,
revised, edited, and printed are major hurdles that can take years.
In many cases for paper and digital maps, the fi nal step involves
transition from fully viable geologic map data into a piece of
carefully crafted cartographic art. That process can separate maps
from underlying data and can result in unacceptable delays in
data distribution. In a rapidly changing world, it is prudent to
favor publication mechanisms that are streamlined and consistent
with funding, staffi ng, and the needs of map users. As new tech-
nologies for creating map data are adopted, it is critical for new
and appropriate modes of review, publication, and distribution to
be adopted as well.
Traditionally, the commitment of geologic lines to paper im-
plied permanence. The entire paper-map production process was
dictated by the pace of base map preparation, compilation of lines
from fi eld sheets, editing, review, and an evolving printing and
distribution process. Thus, the process was well defi ned and could
be streamlined, but it was founded on old technology and old
concepts and expectations. Today, the legacy of past methods
for creating, printing, and distributing maps is incompatible with
modern, digital capabilities and the needs and expectations of end
users. Predigital paper geologic maps have inertia and longevity
in excess of their specifi c relevance by years to decades because of
lags between changes in the scientifi c basis of the map, generation
of new source data, and the pace of traditional map production
methods. One of the greatest practical benefi ts of the digital revo-
lution is the demise of the practice of treating a published printed
104 House et al.
map as an unchangeable archive of data, as opposed to a deriva-
tive product and printed archive of an evolving geologic data set.
We occupy a point in time in which it is possible to create
great effi ciencies in geologic mapping using widely available
tools and enhance the availability and utility of geologic map in-
formation for an increasing variety of users. Major technological
and conceptual advances that allow more dynamic geologic maps
have transpired over the past 20 yr, including particularly impor-
tant ones in only the last decade. Major technological develop-
ments in GIS and GPS alone have transformed many of the ways
that we can collect, create, manage, store, visualize, and distribute
geospatial data. The integration of these two technologies with
digital photography, seamless digital base maps, light detection
and ranging (LiDAR) technology, mobile computing devices, and
social networking platforms engenders new ways to think about
mapping (Pavlis et al., 2010) and data sharing. Modern technolo-
gies provide means of seamless collaboration in data development,
model formulation, and scientifi c interpretation. This changes the
intellectual and operational approaches that geol ogists can use to
construct, interpret, and share geologic maps.
The meaning and intention of the basic activity of generat-
ing lines and plotting points on maps has not changed, but the
tools and techniques for recording, storing, explaining, and shar-
ing them have. The most cursory application of modern tools
can make fi eld and offi ce work more effi cient and improve the
generation and distribution of data. More advanced and systemic
appli cations of new fi eld and offi ce tools open new avenues for
scientifi c collaboration, discovery, outreach, public education,
and emergency managment. They ensure a broader audience
among end users with increasing expectations for data availabil-
ity and interoperability.
GIS: The Core of Modern Geologic Mapping
A geologic map is a structured representation of the geo-
spatial relationships between different types of earth materials.
The most fundamental type of data that a fi eld geologist collects
is the precise location of various geologic features. In the past
much of this location data was approximated via dead reckoning,
topographic inference, triangulation, and barometric altimetry.
Modern GPS technology allows geologists to record geospatial
information much more accurately. The accumulation of geo-
spatial data points requires a geographically aware data manage-
ment system, namely, a geographic information system (GIS).
Geologists make interpretations of the geologic landscape
based not just on fi eld observations and measurements, but also
on their analysis of a wide variety of base data, including: topog-
raphy, represented either as topographic lines, or in more modern
systems, digital elevation models (DEM), geophysical data, aerial
photography, and satellite imagery, among others. As these and
new data sources continue to improve, they will play increasing
roles in all geologic mapping projects. Using such a breadth of
base data types requires their precise geographic alignment. GIS
technologies are not only the key to georeferencing, but they also
have led to the development of software allowing us to vis ualize
these data layers in new ways and combinations. No longer must
we settle for a single base layer for our maps; rather, we can now
choose specifi c base layers and combinations for more robust sci-
entifi c analysis and contextually appropriate portrayals.
GIS provides powerful tools for data analysis, visualization,
and collaboration. The cornerstone of these opportunities rests in
the standardized digital format in which GIS requires us to spa-
tially encode geologic information. Because of that geospatial
standardization, data can be used by a growing variety of software
tools. Data generated as part of a two-dimensional (2-D) geologic
map can be used to constrain the development of three-dimen-
sional (3-D) block models using new and developing software
applications (e.g., Berg et al., 2007; Kessler et al., 2009; Thor-
leifson et al., 2010; Jones et al., 2009). No longer must the only
representation of our geologic map be a piece of paper. Instead,
our data can be used to fuel visualizations draped over and com-
pared to various, end-user–defi ned base layers. No longer must
our maps be constrained to a single scale; we can develop online
applications that can, when appropriate, reveal observations at
larger and larger scales, or smaller and smaller scales. No longer
must interested parties come to our libraries and check out copies
of our paper maps; our data can be hosted in online environments
that provide unprecedented potential for data distribution to any
device with an Internet connection. Such availability presents us
with new opportunities for scientifi c collaboration that were sim-
ply impossible using traditional geologic maps.
In summary, because the precise location of geological ob-
servations is of the utmost importance to proper interpretation of
a geologic map, not using GIS and related technologies to create
new maps renders a serious mapping project obsolete before it
is completed. Nonetheless, the level of integration of GIS into
the mapping process at academic and government agencies can
vary widely. The capabilities of GIS programs are often margin-
alized by graphic arts programs that have circuitous, minimal, or
no connection to a digital geologic database and introduce tre-
mendous ineffi ciencies in creating GIS layers demanded by end
users. As a community, geologists have been relatively slow to
adopt new and useful mapping technologies, but we must if we
intend to recognize the full potential for modern scientifi c col-
laboration, more robust data management, and modern visualiza-
tion techniques.
Base Map Materials: Traditional and Modern
In the United States, fi xed-scale topographic maps have long
been the base map of choice for geologic mapping because they
are standardized, familiar, and show essential reference and use-
ful (though time-bound) cultural information. Topographic maps
have been the standard fi eld mapping base for many geologists, as
well as a common base for depicting the geologic map. Their use
of elevation contours is clean and intuitive, and the maps are gen-
erally legible beneath overprinted geologic data. However, within
the past 10 yr, the availability of high-resolution and timely aerial
Overcoming the momentum of anachronism 105
and satellite imagery has increased dramatically, and to the sig-
nifi cant advantage of geologic mapping in the offi ce and the fi eld.
Many of these high-resolution sources can be “streamed” from a
Web-based image service to a mobile or desktop GIS platform,
and many can be cached in the memory of mobile-computing de-
vices. The ready access to a variety of crisp, georectifi ed imagery
is transformative. Individual mappers (and data consumers) are
able to choose a preferred portrayal of base layers to help evalu-
ate geologic map data within specifi cally meaningful contexts.
Accurate and illustrative base materials provide essential
context for creating, comprehending, and interpreting geologic
maps. Traditionally, base maps for geologic maps in the United
States have primarily been U.S. Geologic Survey (USGS) topo-
graphic quadrangle maps. Base maps not confi ned to quadrangle
shapes (less common) have been created as photomosaics. It is
now much easier to aggregate seamless mosaics of digital im-
ages of these and other types of maps to cover irregular or non-
gridbound areas. New technologies allow for simple combination
of different types of data layers, for example, contour maps atop
high-resolution imagery. Sets of contours can be generated that
are specifi cally appropriate for areas of interest, whereas prior
to digital base data, interpretation or portrayal was commonly
compromised by an inappropriate contour interval.
It is now easy to create base layers tailored to particular types
of maps. Contours can be created from digital elevation data or
by digitally extracting fi eld-surveyed contours from appropriate
legacy data sets for a given area (e.g., 1:31,680 topographic map
series). The U.S. National Elevation Dataset (NED) provides
DEM data based on 10 m to 30 m grid cell sizes and can be used
to generate contours. However, this data set has limitations of
relative scales of actual topography and grid dimensions used to
characterize the topography (Gesch et al., 2002; Gesch, 2007).
NED-based calculated contours are suffi cient in some cases but
are commonly defi cient for complex areas or large-scale por-
trayals, particularly in relation to LiDAR data (Fig. 1).
LiDAR: Panacea or Just Near-Panacea?
The advent of LiDAR technology is a transformative
development in topographic mapping and landscape visuali-
zation. LiDAR elevation data sets have revolutionized geo-
logic mapping in the areas for which they are available. They
can be used to generate very high-resolution, precisely geo-
referenced, and data-rich base maps that are amenable to vari-
ous types of visualization alone or in combination with other
imagery types. LiDAR scanning systems record very precise
250 m
117°4345W 117°43W
Figure 1. Three different types of base maps of the Dogleg Bar area,
Owyhee River, Oregon, showing differences in topographic visualiza-
tion. This is a diverse map area containing a river, river terraces, boul-
der bars, lava fl ow, landslides, and layered bedrock (Ely et al., 2012).
Upper map: excerpt of conventional U.S. Geological Survey (USGS)
topographic map (Lambert Rocks, Oregon); middle map: slopeshaded
grid and 5 m contours from 10 m National Elevation Dataset (NED)
data; and lower map: slopeshade and 5 m contours from 1 m light
detection and ranging (LiDAR) digital elevation model (DEM). With
appropriate tools, the conventional USGS topographic map can be
supplanted or greatly supplemented by the development of alternative
base map layers that better correspond to mapping needs.
106 House et al.
relative point positions and elevations. LiDAR scanning of
vegetated swaths of land results in multiple return values for
proximate points that can isolate vegetation cover (early re-
turns) from bare earth surface (late returns). The multireturn
aspect has revolutionized geologic mapping because it can
be exploited to generate high-resolution digital terrain mod-
els of the land surface beneath heavy forest cover, revealing
rich detail (Fig. 2). This aspect of the method creates stunning
topographic representations of forested lands and leads to new
discoveries and insights in geologic studies (e.g., Haugerud
et al., 2003; Haneberg et al., 2005).
Postprocessed LiDAR point data provide a robust basis for
developing DEMs and contour maps to facilitate geologic map-
ping. Landscape representations from high-resolution LiDAR
data form fantastic base maps for geologic mapping because
of their clarity, resolution, and geometric precision. LiDAR
point data can be generalized into DEMs of a range of reso-
lutions to create realistic and astoundingly revealing hillshade
and slopeshade representations of the land surface (Fig. 3). They
are particularly useful for surfi cial geologic maps because of
their strong affi nity to geomorphic representation (Frankel and
Dolan, 2007; Howle et al., 2012), but they provide accurate
topo graphic data and precise positioning relevant to any kind of
geologic mapping and characterization (e.g., Glenn et al., 2006;
Deardorff and Cashman, 2012; Jones et al., 2009; Burton et al.,
2011; Crow et al., 2008).
Ideally, LiDAR would form the basis of a national, up-
dateable topographic mapping program because it can gener-
ate map data that are superior to traditional topographic maps
and the relatively new U.S. Topo map product (USGS, 2009).
The availability of LiDAR data have had and will certainly con-
tinue to have a major impact on topographic and geologic map-
ping (Buckley et al., 2008). The availability of high-resolution
LiDAR on a national scale in the United States would have
incalculable value for science, land management, emergency
management, and regional planning. Recently, the Ore gon De-
partment of Geology and Mineral Industries (DOGAMI) and
the Oregon Lidar Consortium have developed a series of topo-
graphic quadrangle maps based on LiDAR of selected parts of
the state. These maps are more accurate, timely, and far more
easily updateable than corresponding USGS topographic quad-
rangles. The accuracy of the data sets allows generation of con-
tours down to intervals of 2 ft (0.6 m) (DOGAMI-OLC, 2013).
Seamless Digital Maps and Virtual Globes
Imagine if your fi rst glimpse of a globe was of one that could
be spun, panned, and zoomed at will to any spot on the planet,
or if your fi rst experience with a map outdoors was a seamless
image of Earth on the screen of your mobile computing and tele-
communication device that followed your progress through the
world. These are the realities of modern digital maps and globes
that are ever-present on tens of millions of desktop computers
and mobile devices. Their forerunners, no matter how integrated
with traditional thinking they may be, are quaint by comparison.
Seamless digital maps offer tremendous promise in the develop-
ment and dynamic display of geological maps and data sets. They
are mesmerizing sources of insight with great potential for illus-
trating, understanding, and sharing the context of geologic map
data sets and related ideas and interpretations.
Functional seamless digital maps and globes with extensive
collections of high-resolution imagery have only been widely
available since 2005 and have had profound impact on geosci-
ence in this short time (cf. Whitmeyer et al., 2012). They are par-
ticularly useful tools for education and virtual geologic explora-
tion and reconnaissance (e.g., Lisle, 2006; Fig. 4). They are also
extremely useful for fi eldwork planning and fi eld data archiving,
management, and sharing. On mobile platforms, seamless digi-
tal maps can be used for virtual and real-time reconnaissance. In
areas with particularly good exposures and high-resolution im-
agery coverage, it is easy to identify and record the coordinates
of key exposures of geologic units for future investigation in the
eld. Furthermore, it is possible to quickly scan a map area (or
surrounding area) for particularly good sites to help characterize
regional and local geology. Seamless digital map services that
update regularly, and retain archives of historical aerial (e.g.,
Google Earth, National Agriculture Imagery Program [NAIP]),
oblique (e.g., Bing Bird’s Eye) and georeferenced ground-based
photography (e.g., Google Streetview) provide important histori-
cal context and can highlight existing and new exposures cre-
ated by geologic processes, construction, or land-use change for
targeted fi eldwork related to map revision (Fig. 5). Current re-
search in Virtual Globes as “virtual geologic instruments” with
exceptional spatial resolution shows great promise for detailed
geologic mapping and fi eld data collection on this intuitive type
of platform (Bernardin et al., 2011).
New Tools: Digital in the Field
Field gear preferences and personal protocols for observa-
tion and data collection are the core of geologic fi eldwork. Some
eld gear items have iconic status that stems from utility and
deep-rooted traditions. For example: the pocket transit, the rug-
ged fi eld book, the acid bottle, and the rock hammer are all time-
honored traditional equipment. No technological advance has
obviated the utility of the acid bottle or the hammer, but other
tools have capable modern counterparts that can be astonishingly
useful in comparison to traditional tools. Foremost examples
among these are the handheld GPS unit, the digital camera, and
the mobile computing device. Each of these items can be used to
great advantage for improved effi ciency of time and effort in cre-
ating geologic maps and can support a consistent fl ow of digital
data from the fi eld to the offi ce and to collaborators. Indeed, as
technology and software continue to evolve, each of these func-
tions is now possible with some singular mobile devices.
There is a persistent, progressive thread of interest in devel-
oping a complete digital geologic mapping solution for the fi eld
(e.g., Brimhall et al., 2002; Clegg et al., 2006; Alfarhan et al.,
Overcoming the momentum of anachronism 107
~line of prole
Figure 2. Light detection and ranging (LiDAR)
maps (hillshade, top; slopeshade, bottom) and
corresponding topographic map excerpt (cen-
ter) of McKenzie River area, central Oregon
(Tamolitch Falls, Oregon, U.S. Geological
Survey 7.5 quadrangle). In this comparison,
the LiDAR visualizations highlight details that
are absent from the conventional topographic
map, including: the textured surface of heavily
forested young lava fl ows and a prominent top-
ographic “pimple” in excess of 100 m (330 ft)
high (profi le in lower image), in addition to
other topographic features. LiDAR images
courtesy of Natalia Deligne.
108 House et al.
2008; Jordan, 2010; Knoop and van der Pluijm, 2006). However,
while methods of direct creation of digital lines and database
editing in the fi eld are available, it is neither appropriate nor
ideal under all circumstances. The quality of sophisticated GIS
editing in the fi eld varies with equipment, scale, environmental
conditions, comfort, and the type of data being recorded. For
example, point data types, notes, and photos are ideal for collec-
tion in the fi eld. It is inevitable that improvements in the ease of
direct fi eld collection of all data types will eventually see impor-
tant technological and methodological innovations. However, a
complete fi eld solution may not be necessary if it is possible to
approximate or maintain seamless integration of one’s fi eld and
offi ce efforts. For example, high-resolution custom base maps
can be printed from a virtual globe or desktop GIS application;
these fi eld maps can be marked up with pens and then scanned
or photographed in the fi eld (or offi ce) and subsequently digitized
or used to guide compilation on the same imagery on a desk top
computer (Pavlis et al., 2010). Final compilation of a com-
plicated geologic map in one’s climate-controlled offi ce may
currently be the better solution as it allows for some degree of
post-fi eldwork quality control.
Geocoded Field Data Collection and Sharing
Geology is deeply if not recursively embedded in the “geo-
spatial” realm. Knowing one’s location on Earth is essential to
characterizing that location’s geology. Traditional skills of self-
location on the map with maps and photos are crude in compari-
son with modern geologic mapping in an era with easy access
to the GPS. GPS-enabled devices can create accurate records
of one’s movement through a fi eld area, and the correspond-
ing geospatial data can be recorded and embedded on digital
media created in the fi eld, including photographs of geology,
photos of fi eld notes and sketches, video and audio recordings,
and textual data. Most digital data collected in the fi eld can
be instantly shared with colleagues for review and archiving.
Figure 3. Light detection and ranging (LiDAR) digital elevation model (DEM) visualizations of an 11 km segment of the Owyhee River, Oregon.
Left: hillshade; center: slopeshade; right: slopeshade with semitransparent, colored elevation ramp (lowest: pink-purple along river; highest: green-
yellow along rim of canyon). Width of each panel is ~2.5 km. Slopeshade maps, unlike hillshade maps, do not have modeled shadows. Their tonality
indicates variation in slope and is, thus, independent of an illumination direction. Geologic map of this area can be seen in Ely et al. (2012).
Overcoming the momentum of anachronism 109
Figure 4. An example of fi eld observation documentation on a virtual globe. This image shows the locations of geotagged fi eld photographs collected
in the Owyhee River area, Oregon (including part of the area shown in Fig. 3). These images were collected on a series of traverses. The traverse lines
can also be plotted, but are not shown to preserve clarity of the map. Photograph locations (green dots) are shown on a terrain-enabled virtual globe
(Google Earth) with semitransparent light detection and ranging (LiDAR) slopeshade overlay and geologic map overlay. Small photograph shown
in lower right is from link to higher-resolution image. The view in the photograph is to the north. See Ely et al. (2012) for geologic map information.
Figure 5 (on following page). A portion of a traditional topographic map (top) (Ayer 7.5 quadrangle, Massachusetts; U.S. Geological Survey
[USGS], 1950) compared with a modern custom printable base map of the same area quickly constructed in a geographic information system (GIS)
from slopeshaded light detection and ranging (LiDAR) data (bottom) (USGS, 2011), overlain by recent land cover data (2005; green—forest ,
yellow—commercial, gray—open/new power/natural gas lines), hydrography and wetlands (2010 and 2009), roads (2012), and areas that have
undergone development or other land-cover change (magenta) and may contain new and unmapped bedrock exposures. The areas of potential new
exposure were identifi ed by comparing U.S. Department of Agriculture (USDA) 2004 vs. 2012 National Agriculture Imagery Program (NAIP)
orthophotography via the “difference” method in GIS software. The custom base map is superior to the traditional map for planning traverses and
relating outcrop-scale features to map-scale geomorphology. It is also useful in conjunction with traditional map data for highlighting features such
as abandoned forest roads and railroads, new buried gas pipelines and transmission lines, etc. Data obtained from MassGIS (
110 House et al.
N 42°34
Figure 5.
Overcoming the momentum of anachronism 111
Judicious use of a digital camera and a GPS-enabled device in
the fi eld is essential fi eld practice and a simple means of compil-
ing part of a digital data archive (Fig. 4). Data from each device
can be integrated in a simple way to create “geotagged” media
that are meaningful to the development and understanding of
the map. Related methods allow simple geocoding of scanned
historical photos and slides to build useful archives of one’s pre-
digital work in the fi eld.
Most social media and online photo-sharing applications
recognize geotags and can create links to online map services
that allow viewing on a seamless digital map or mosaic of high-
resolution imagery. Albums of geotagged images can be created
and shared for purposes of collaboration, peer review, and supple-
menting published geologic maps and data sets. The simple process
of geotagging photos, notes, data, and related media should be a
default protocol for all fi eld scientists who are concerned with the
location of things they deem worthy of documentation. It is also
a very effective aide-memoire during compilation of fi eld efforts
(Fig. 4). Geo-encoded pictures, notes, and illustrations can also
enhance the peer-review process by providing meaningful con-
text for map content in lieu of fi eld visits if necessary.
New Tools: Mobile Computing Devices
Rugged laptop computers and tablets or smart phones in
protective cases are becoming essential to geologic fi eldwork. As
technological advances have accrued, the functionalities of indi-
vidual devices have been combined. For example, in the (only)
5 yr since the development of the fi rst iPhone, it and similar
Android smartphone devices and tablets have quickly become
remarkably useful fi eld tools, with or without cellular data sig-
nals. Numerous, affordable handheld devices come equipped with
the following: cameras (video and still), GPS chips, magnetom-
eters, triaxial accelerometers, compasses, fast computer proces-
sors, cellu lar telephone, and gigabytes of available digital storage.
These capabilities allow fi eld geologists to record traverses, take
and annotate pictures, navigate on high-resolution imagery, col-
lect and record structural data, take voice or text notes, and share
data instantly with colleagues when cellular data coverage allows.
Having these functions in a single device reduces the weight and
bulk of fi eld equipment. Adequately appointed mobile devices can
also house large repositories of scientifi c literature, making it pos-
sible to enter the fi eld with a complete reference library about the
map area in a very portable format. This can also include copies of
geologists’ fi eld notes, georeferenced geologic maps of the area,
historical and contemporary aerial photography, and virtual fi eld
guides of rock characteristics, fossils, grain size, soil color charts,
etc. The utility of having these things immediately at your dis-
posal while composing a site description or geologic summary in
your notebook or in a note-taking application on a mobile device
is transformative. Of course, modern devices are fragile, can be
lost, and have specifi c power requirements—caveats that apply
equally or in varying degrees to traditional fi eld tools. Similarly,
their use also involves a learning curve.
The aforementioned tools are fundamental to the transforma-
tion of geologic thinking in the development of geologic maps and
underlying data sets. The transformation is away from geologic
maps as static and singular representations to diverse portrayals of
singular and composite aspects of underlying, dynamic geologic
data sets in a sense, a living geologic map.
A living geologic map is one that can accommodate collab-
orative mapping and editing from remote locations and shared
high-resolution imagery sets. It incorporates digital fi eld data
(notes, photos, etc.), covers an area of thematic interest, or is
driven by other priorities, and it resides in or as part of a well-
managed and adaptable master database. It can output digital and
paper maps that refl ect core data and related derived data at any
point in time, but it will be explicitly known that all such discon-
nected outputs are time-bound archives. In other words, a living
geological map easily accommodates map changes in response to
geologic, societal, and scientifi c changes.
These and other ideas put forth in this paper refl ect the
sentiments in the following parts of the National Cooperative
Geologic Mapping Reauthorization Act of 2009 and data man-
agement principles outlined by the National Research Council
§ 31c. Geologic Mapping Program
(c) Program objectives
(3) application of cost-effective mapping techniques that assemble,
produce, translate and disseminate geologic-map information and that
render such information of greater application and benefi t to the pub-
lic; and
(4) development of public awareness of the role and application of
geologic-map information to the resolution of national issues of land
use management.
In order to achieve these goals listed in the act, the concep-
tual and operational frameworks of geologic mapping must be
aligned with new technologies for collecting, managing, and
distributing usable data. This will involve rethinking core, tra-
ditional components of geologic mapping. Synergistic combi-
nations of GIS, seamless digital maps, modern fi eld tools, and
network-based data sharing will permanently transform our
conceptions of geologic maps and their continuing role in geo-
logical science. The wide availability and adoption of these tech-
nologies have already forever changed cultural perceptions of
maps: how they work, what they are for, how to access them, and
even how to edit them. Maps are now seen as interchangeable,
seamless, timely, and containing links to new and more detailed
information. Global network interconnections and access to all
manner of online mapping and media-sharing applications have
increased global geographical awareness signifi cantly, including
the impacts of natural hazards and climate variability on soci-
ety and landscapes. It is inevitable that these cultural changes
will infl uence the future of geologic mapping and increase ex-
pectation levels of users of geologic information. The geologic
112 House et al.
mapping community needs to be able to deftly adapt to chang-
ing technology and changing expectations to remain viable and
The consumption of maps on computers and mobile de-
vices has permanently transformed cultural perceptions of maps
as static pictures on rectangular paper. Maps are now being
produced and consumed as unbounded, fl uid, and multilayered
representations of regions of interest (e.g., Google Earth, Bing
Maps). A corresponding transformation in traditional concepts of
geologic map boundaries should also occur, although the likeli-
hood of them soon becoming seamless at a broad range of scales
is low. Physically irrelevant grid designations (i.e., USGS topo-
graphic maps), constraints of printing technology, institutional
preferences, and some program requirements have dictated the
boundaries of the majority of traditional paper geologic maps.
The promulgation of a quadrangle-mapping model occurs at
progressively greater detriment to scientifi c discovery and col-
laboration in the face of modern mapping methods and steadily
increasing end-user expectations.
The use of more intuitive and pragmatic boundaries based
on physical geologic system domains is preferable in many
areas and can be readily accommodated in the digital mapping
environment. Modern digital methods have all but eliminated
any need for a quadrangle-mapping model. A philosophical and
operational shift toward mapping within limits defi ned by geo-
logic or other physical domains instead of grid cells may engen-
der a transformation in geologic thinking. John Wesley Powell’s
(1890a, 1890b) forward-thinking map of proposed drainage dis-
tricts in the arid states is a notable case in point (Fig. 6). This kind
of approach is more consistent with how geologists think when
making a geologic map and related interpretations. It is literally
thinking outside of and beyond the box and focusing on phenom-
ena related to scales of natural systems. A fl exible perspective
on meaningful map boundaries will lead to greater intellectual
continuity and interest, and greater responsiveness to social and
scientifi c needs. Contextually meaningful boundaries and im-
proved interagency collaboration will help mitigate the com-
mon frustrating problem of inconsistent or mismatched mapping
along boundaries between geologic maps by different agencies
or authors. The reliance on natural system boundaries may con-
ne the problem of harmonization of map units to zones where
changes actually occur in the geology. The standard 7.5 topo-
graphic quadrangle renowned in the United States nicely serves
as an informal unit of areal measurement and progress tracking in
regional mapping projects, but it need not necessarily be the basis
for delimiting geologic mapping efforts.
Traditional topographic maps were not compiled with the
notion of digital in mind. They suffer from similar liabilities as
traditional geologic maps. Cultural data are commonly out of
date the day the maps are printed, and their depiction of hydro-
logic features can vary tremendously. The maps are confi ned
to grid cell windows on the landscape and have characteristics
(e.g., contour interval and measurement unit) that do not accord
well in all cases with adjacent grid cells. In the United States,
the response to this has been the development of the USTopo
program or, “the next generation of topographic maps” (USGS,
2009). This relatively new program is an earnest but only partial
accommodation to the needs of the modern map user. It includes
a digital map with multiple layers, including: imagery, contours
calculated from DEM data, hydrography, cultural features, grid,
and collar. Unfortunately, it is currently constricted by the quad-
rangle format, requires proprietary software, and is not cleanly
inter operable with GIS software.
A printed (or cached) map is only a representation of an area
at a single point in time—a temporal or contextual snapshot of an
instantaneous status of an evolving database of geospatial infor-
mation. The liberation of maps from an exclusively paper format
opens many possibilities for creating living geologic maps that
are updateable in meaningful and important ways and in useful
time frames. Geologic maps are impermanent and incomplete
representations of both the state of scientifi c knowledge and the
state of the landscape. Their traditionally apparent permanence
belies dynamics in geologic processes and thinking, and mapping
technology. Like any snapshot, a static geologic map is instantly
obsolete except as an archive with respect to future changes.
Thus, geologic maps should change as regularly as is practical
in response to three major variables: changes in the geologic
character of the landscape, creation of new mappable data, and
changes in geologic ideas.
Previously mapped areas that undergo signifi cant geologic or
anthropogenic change should be updated as regularly as is war-
ranted or possible. Critical areas with tendencies to undergo fre-
quent change can be mapped in a “monitoring” context in which
minor or major changes can be recorded systematically and in a
timely fashion in order to characterize the geologic behavior of
dynamic, possibly hazardous systems (Fig. 7). This could include
areas of recent fl ooding or active erosion and deposition, including
storm-related coastal impacts, major fl oods, rapid land subsidences,
and a variety of active volcanic or seismic events, among other
types of geologically driven change. If any of the foregoing events
(or others not mentioned) had transpired the day before a mapping
project was undertaken, their consequences would be mapped and
documented as a matter of course; however, if the events occurred
one week after a map was “turned-in” or printed, updating in a
timely fashion is less likely. In areas of extensive development,
anthro po genic changes can create new geologic data at a pace
that renders traditional maps out of date within years. In heavily
forested or urban areas with poor exposure, rapid development,
mineral exploration, land-use change (Fig. 5), and/or construction
of new infrastructure create abundant new surface exposures and
subsurface and geophysical data that require map updates.
Overcoming the momentum of anachronism 113
Figure 6. Arid Region of the United States Showing Drainage Districts: A map showing subdivision of the western United States
by natural “drainage commonwealths” by John Wesley Powell (1890a, 1890b). He proposed these divisions as units of resource
governance circumscribed by meaningful physical boundaries (hydrological in this case).
114 House et al.
The other primary type of change is scientifi c in nature, in-
cluding new paradigms (i.e., modern plate tectonics), new geo-
chronological data, recently discovered key beds and exposures,
advances in structural and petrologic analysis, and remotely
sensed data that reveal previously unrecognized mappable char-
acteristics and relationships. Digital maps can be readily modi-
ed to refl ect these new data and interpretations.
In order for the approach to creating geologic maps to
change, agencies with mapping responsibility need to adopt a
practice of accommodating change in previously mapped areas
as standard procedure instead of an inconvenience. The geologic
mapping community must accept the need for and value of a
program of managed mapping wherein signifi cant, high-priority
changes can be accommodated in a timely fashion. GIS work-
ows in elds such as watershed and infrastructure management
have demonstrated that this type of managed mapping is both
possible and easily facilitated (e.g., Hassey et al., 2010).
Traditional bedrock and surfi cial geologic maps are ultimately
a niche product, the embodied utility of which is largely limited
to geologists. They are not readily accessible to those without
geological training. Nontraditional and unanticipated derivative
uses of geologic maps, to great societal benefi t, have been long
established (e.g., Bernknopf et al., 1993; Bhagwat and Ipe, 2000;
500 m
Figure 7. Series of geologic map excerpts showing channel change along an ~3 km reach of the Bill Williams River,
Arizona, between 1953 and 2005 (House et al., 1999, 2006; House, 2013, personal obs.). This fl uvial system is a prime
candidate for inclusion in an easily updateable geologic map database. Each map has a suite of colors that indicates simi-
lar channel and fl oodplain features at discrete points in time between 1953 and 2005. The map polygons from each gen-
eration are not overlays in the subsequent generations; they instead are topologically coherent polygons. Thus, each map
retains some amount of each previous map’s polygons. The maps document an increasingly complex mosaic of young,
but different-aged geologic deposits. Creating and analyzing a spatially and temporally intricate geologic map such as
this require a geographic information system (GIS) and a series of digital, orthorectifi ed historical aerial photographs.
The geomorphology of this river changes signifi cantly on a 5–10 yr time frame, and its present confi guration is certainly
somewhat different from the most recent mapping (2005) shown in this fi gure.
Overcoming the momentum of anachronism 115
Thomas, 2004). Derivative map products, compiled from tradi-
tional geologic maps and combined with additional types of data
not necessarily collected during original fi eld mapping (such as
digital topography, material strengths, rock fractures, mineraliza-
tion and oxidation zones, landslide features, stream-bank erosion,
and springs, as well as borehole data, geophysical data, and geo-
technical data) constitute primary interests of many con sumers of
geologic maps. GIS has made the construction of such maps far
simpler and more effi cient than using traditional methods. Exam-
ples are abundant (Thomas, 2004) and include fl ood hazard maps
(House, 2006; House et al., 2010a), seismic hazard maps (Wills,
2010), landslide hazard maps (Radbruch-Hall et al., 1982; Godt,
1997), land-use planning maps, karst maps, hydrostructural do-
main maps (Kopera et al., 2006), and maps of sand and gravel re-
sources (e.g., Walling, 2000), among many others. Derivative uses
of geologic data with societal benefi t are now the implied man-
date and primary justifi cation for mapping programs in the United
States (U.S. Congress, 2009, 43 USCS § 31c; USGS, 2012), with
some states mandating production of derivative map products (e.g.,
Wills, 2010). As such, developing digital geologic map products
with an aim toward their derivative use, including collecting non-
traditional fi eld data during mapping, and generating derivative
products to meet contemporary stakeholder demands, should be
considered a normal component of geologic map production.
Traditional methods in paper geologic mapping have com-
monly been relatively insular undertakings for many mappers, in
part because of basic methods, materials, and nonoptimal means
of collaboration. However, modern digital methods make work-
ing in isolation or solely with manual methods anachronistic and
counterproductive. A larger interest in the broad dissemination
of geologic map data for application in the research of others
requires greater emphasis on scientifi c collaboration, sharing,
and interoperability in digital geologic map development. The
traditional insularity of geologic mapping will yield to expand-
ing opportunities for collaborations that are possible with new
technologies and, ideally, new demands for geologic map data.
Collaboration on complex maps is essential, and there are new
ways to coordinate and manage groups of mappers and fi eld sci-
entists. This transformation can signifi cantly enhance effi ciency
in data generation and collection.
Crowdsourcing is a popular term for a surprisingly powerful
mode of collective action or distributed collaboration (e.g., Shirky,
2008) that leverages global Internet connectivity via smart phones
and computers to coordinate large numbers of people to attain a
common goal. The online encyclopedia Wikipedia (Wikimedia
Foundation, 2013) is a stellar example of the potential for crowd-
sourcing to achieve constructive goals that were unthinkable only
10 yr ago. A growing trend in online social media involves active
(and occasionally inadvertent) sharing of geocoded digital media
(e.g., photos and messages). Striking patterns result when large
numbers of these posts are aggregated in a passive form of map-
data crowdsourcing. For example, Fischer (2010) has developed a
series of maps of world cities by aggregating geospatial data from
thousands of independently collected and geolocated posts us-
ing various social media sharing services (Fig. 8). The increasing
amount of geocoded and shared information on the Internet allows
for a surprising diversity of thematic maps (Graham and Zook,
2011). This cartographic outcome derived from independently
collected information portends great possibilities for coordinated
collec tion of specifi c types of geocoded data (Heipke, 2010).
The development of maps with crowdsourcing is a relatively
new idea. OpenStreetMap (OSM) is probably the best example.
It is a “collaborative project to create a free editable map of the
world” (OSMF, 2013) that has leveraged the efforts of a large
number of dispersed contributors to generate a free, feature-rich,
and seamless map of the world. The OSM platform for collab-
orative editing is very popular and offers important potential for
collaborative geologic mapping. For example, the USGS (Wolf
et al., 2011) has evaluated the OSM approach for crowdsourcing
road and trail data to include in the National Map (USGS, 2013a,
2013b). Goodchild (2007) termed the phenomenon of crowd-
sourcing in relation to geolocated information “volunteered
geographic information” (VGI). The OSM model may be better
characterized as an example of “contributed” geographic infor-
mation (CGI), wherein the contributors are focused on a single
goal, and the input is mediated or vetted by community members.
The crowdsourcing approach has seen great success in di-
saster response situations in which reliable and timely geospatial
data are badly needed. Following the Haitian M 7.0 earthquake in
December 2010, satellite high-resolution imagery collected soon
after the disaster was made available by GeoEye, Inc., for use
as base imagery in crowdsourced mapping efforts to create near
real-time maps of the affected area (Zook et al., 2010). A com-
bination of crowdsourced mapping and geocoded social media
postings was critical in rescue and relief efforts in this instance.
Such focused efforts attest to the value of crowdsourcing geo-
spatial information, particularly when the goal is well defi ned. It
is important to note that unmediated application of crowdsourced
data may face real concerns about validity and reliability (e.g.,
Elwood et al., 2012; Sui et al., 2013). A data vetting process is
warranted in most cases, but it has been argued that the benefi ts
of crowdsourced data may outweigh the risks in emergency re-
sponse situations (Goodchild and Glennon, 2010).
Collaborative GIS: Crowdsourcing for Geologic Mapping
In the context of geologic mapping, “crowdsourcing” re-
fers to a distributive model of effort-pooling and coordination
toward a common goal. An effi cient and high level of organized
116 House et al.
© OpenStreetMap (and) contributors, CC-BY-SA
Figure 8. Map of the San Francisco Bay region
from (top; 2013) compared
to crowdsourced virtual street map of the San
Francisco Bay Area, California, derived from geo-
tagged photographs aggregated from online photo
sharing services Flickr and Picasa in 2010 (bot-
tom; Fischer, 2010); Online linkage to the bottom
image: http://www.fl
/4622375804/in/set-72157623971287575. Figure
used with permission from Eric Fischer.
Overcoming the momentum of anachronism 117
collaboration is possible with a multi-user, versioned geodata-
base structure within an application like ArcSDE™ or ArcGIS
for Server (ESRI, 2013). A version-based approach allows the
management of simultaneous and nonconfl icting edits of con-
trolled duplicates (versions) of all or part of a large, multi-user
geodatabase. This approach is the only feasible way to seam-
lessly manage a team of map contributors in a geologic map-
ping effort (including geologists, editors, and cartographers). It
can be managed for effi cient data entry in ways that are medi-
ated by rules and permissions. Thus, multiple contributors can
interact with the database simultaneously from remote locations.
Populating and coordinating a team of highly skilled geologists
and GIS specialists can generate high-quality maps with great
effi ciency using this approach. This is a promising model for the
future of geologic mapping. It can solve many practical and lo-
gistical diffi culties frequently encountered in a multi-authored
geologic mapping effort and allow for rapid and effi cient produc-
tion of geologic maps of large areas in a reasonable time frame.
The Nevada Digital Dirt Map Experiment (House, 2010) is
an example of a successful collaborative geologic mapping proj-
ect that employed a multi-user, versioned database to develop a
surfi cial geologic map of Clark County, Nevada (20,960 km2),
in 18 mo. It involved simultaneous editing of a shared geologic
map database by a team of up to 18 GIS-savvy geologic map-
pers and editors at a single time (Fig. 9). The multiple mapper
approach was managed to handle a common suite of basic is-
sues in regional geologic mapping: compilation and refi nement
of published geologic linework; addition of newly created data;
harmonization of inconsistent nomenclature over broad areas and
at “boundary faults” between compiled map sources; and optimi-
zation of mapping scale across very large areas spanned by com-
piled and new mapping. The effort demonstrated that effi cient
production of multi-authored geologic maps could be accom-
plished given appropriate means of effort and skill coordination
among the mapping and editing team.
All of the aforementioned tools, methods, and concepts are
promising, though complicated. There are variably steep learn-
ing curves and potential data “avalanches” that require workfl ow
and protocol adjustments, and training and planning. Nonethe-
less, transformation is under way, and it is critical for our science
that we act collectively to best determine our direction. Digital
geologic data and map products, in spite of all their advantages,
do have various pitfalls that commonly make them no more a
panacea than traditional paper geologic maps. Most of these is-
sues, however, stem from individual and/or institutional attitudes
toward digital data and a lack of foresight, knowledge, planning,
and appreciation for the scope of complex issues involved in
reaping the full benefi ts of transitioning to digital data models
(National Research Council, 2009). This section hopes to address
some of these issues.
50 km
Figure 9. Screen-captured images of two stages of progress in the
“crowdsourced” Nevada Digital Dirt Mapping Project (House, 2010;
House et al., 2010b). Colors in upper image show compiled, previously
published mapping (red) and “personalized” contributions and edits by
the team of 18 mappers (various other colors). Lower map shows a near-
nal version overlain on a 30 m digital elevation model (DEM).
118 House et al.
Delineation of Patterns, Not Necessarily Geology
A potential criticism of mapping with GIS and high-reso-
lution imagery is that it can degrade the intellectual process of
creating a geologic map to one involving spatial inventory. It is
relatively easy to delineate like-kinds of objects, patterns, and
textures observable on high-resolution imagery in absence of a
clear understanding of their geological meaning, thus diluting the
intellectual fi eld-based experience of geologic mapping. How-
ever, the advantage of technological developments cannot be out-
weighed by a potential loss of intellectual insight. Modern digital
methods in geologic mapping and 2-D/3-D map visualization can
help engender a deeper, more intuitive understanding of the land-
scape that is signifi cantly enhanced through subsequent or even
concurrent fi eld investigations (Whitmeyer et al., 2009). It is the
same situation as holds for analysis of aerial photograph stereo-
pairs: It contributes to more effective fi eldwork and leverages that
eldwork to effi ciently produce quality maps.
The Persistent Need for Fieldwork
The increasing availability of diverse, high-resolution imag-
ery does not eliminate the need for fi eldwork—consider the ex-
ample of the exploration of Mars. Early expeditions beginning in
the 1960s collected remotely sensed data of unprecedented value
for interpreting the planet’s geology (Carr and Head, 2010). Years
of analyzing the remotely collected data led to great discoveries
and to the development of increasingly complex supporting tech-
nologies. It is, however, remarkable to consider that the follow-up
to years of data collection through remote sensing of the Martian
surface was to send robot geologists as human proxy to collect
samples and photographs (e.g., Crumpler and Arvidson, 2011).
This may be the ultimate example of how ground-truthing or
eld-checking of remote interpretation is fundamental to mod-
ern geology. As we gain more outstanding imagery of Earth’s
surface, our need to document what it is actually on the ground
is likely to increase, although it may become focused on progres-
sively more specifi c features. Furthermore, some aspects of geo-
logic study, such as sample and fossil collection, description of
lithologic characteristics, or resolution of structural complexity
in areas of dense vegetative cover, cannot be replaced by analysis
of remotely collected data.
Challenges Inherent with Digital Data
The use of GIS and other software for geologic data organi-
zation, management, analysis, and distribution has become much
more effi cient and robust than traditional, paper-based means of
data organization. The inherent geospatial component of all data
in a self-contained GIS eliminates the need for methods of data
organization that use separate paper maps commonly employed
for different types of data. Unfortunately, the learning curve for
uency in GIS and associated software can be quite steep, and
maintaining knowledge of current best practices for data visual-
ization and management can require a very signifi cant organiza-
tional investment in time and resources.
The number and nature of ways in which end users can fi nd
a map they need, collectively known as “data discovery,” have
exploded in the past decade and can rapidly change. Simply pro-
ducing a map, fi ling it away in a library, and/or perhaps posting
it on a Web site offer no guarantee that people will be able to
nd and access it. A sophisticated and evolving knowledge of
contemporary Web publishing practices, inclusive of the con-
stant maintenance of fi le formats, online data linkages, search
engine dynamics, social media, commonly used map databases,
keyword management, etc., is crucial to ensuring that a geologic
map will not disappear into obscurity as soon as it is published.
By providing geologic data online and in GIS formats, we
allow GIS-savvy end users to construct their own maps and inter-
pretations from raw source data in useful and powerful new ways.
Unfortunately, such secondary interpretations may suffer from
a lack of understanding of the primary data. Thus, it is critical
to design digital map products in ways that preserve and convey
interpretations and intentions of the primary authors in a format
interpretable by secondary users. Various solutions exist amongst
proprietary software packages for controlling the depiction of
map elements in GIS, but dependence on such proprietary solu-
tions only solves the problem for the community of users of that
proprietary tool, and hence it is not an adequate general solution.
Standardized metadata (i.e., Federal Geographic Data Committee
[FGDC]), including thorough layer and feature attribution, is an
essential component of ensuring that the user can properly inter-
pret elements within a GIS database. The present lack of good
metadata describing our geologic data is indicative of the diffi -
culty of its generation, and of the lack of investment of resources
toward what is a necessity in modern data management practice.
Maintaining longevity of digital data requires a sustained and
consistent human effort over decades to address a host of peren-
nial issues (e.g., The Commission on Preservation and Access
and The Research Libraries Group, 1996; Digital Preservation
Coalition, 2008; National Research Council, 2009). Data need
to be frequently transferred to new physical media (“refresh-
ing”). The useful lifetime of physical digital storage media is
short, with digital archive organizations typically retiring media
after 3–5 yr (e.g., Internet Archive Collections Team, 2011). The
physical location of the storage media needs to be considered
for data security and resilience to natural and societal disasters.
The format of the data itself needs to be routinely updated (“data
migration”) to formats that can be accessed by contemporary
software. Online links to map products and map databases need
to be maintained. Working relationships need to be established
with the library science community and appropriate digital data
repositories, which research and conduct many, if not all, of the
previously mentioned functions. Full recognition of the forego-
ing issues will be crucial to map publishing in the digital age.
The ability to collect, store, and distribute vast quantities
of digital data in ways that allow for widespread application re-
quires systematic and standard methods of data management.
Overcoming the momentum of anachronism 119
Increased effi ciencies in and uptake of digital map data genera-
tion can result in an indecipherable avalanche of data without a
well-planned management structure. The nature of digital data
introduces vulnerability to a variety of problems unique to the
digital age. If these problems are left unchecked, they can render
data completely useless. Digital data management is fundamen-
tal and unavoidable, and it absolutely must be recognized as an
essential component of modern geologic mapping that requires
dedicated GIS and information technology (IT) professionals.
These complex responsibilities should not fall exclusively on the
shoulders of geologic mappers:
Although all researchers should understand digital technologies well
enough to be confi dent in the integrity of the data they generate, they
cannot always be expected to be able to take full advantage of new
capabilities. In an increasing number of fi elds, professionals with ex-
pertise specifi cally in the generation, analysis, storage, or dissemina-
tion of data are playing an essential role in taking advantage of digital
technologies and ensuring the integrity of research data. … Research
institutions, professional societies, and journals should ensure that
the contributions of data professionals to research are appropriately
recognized. In addition, research sponsors should acknowledge that
nancial support for data professionals is an appropriate component of
research support in an increasing number of fi elds. (National Research
Council, 2009, p. 5)
Sound data management is fundamentally a computer and li-
brary science problem, and it requires a solid foundation in data-
base design, an understanding of a variety of software packages,
some understanding of the technology of modern computer net-
works, and knowledge of the ever-changing landscape of digital
distribution mechanisms. These are not areas in which a geologist
is traditionally trained. Likewise, those trained in computer and
library science lack the background and investment required to
understand the details of the information that the geologist strives
to convey. This means that geologic mapping teams need to have
access to computer and library science professionals who help
geologists effi ciently collect digital data, and who are also re-
sponsible for the maintenance of those data. We cannot expect a
geologist to invest the time and resources that would be required
to take care of these data management issues and still be able to
focus on being a good geoscientist. Conversely, geologists need
at least some level of fl uency in the digital world in order to com-
municate their needs to those capa ble of performing appropriate
data management.
Thus, the inevitable burden of digital data management re-
quires the provision of resources (i.e., time and money) toward
the employment of GIS professionals (IT specialists and car-
tographers), rather than solely to geologists. While the advan-
tages and effi ciency of using modern digital tools can pay for
themselves over time, often the initial adoption of such systems
requires signifi cantly more resources than may presently be al-
located to geologic mapping projects. Many traditional funding
sources for geologic mapping fail to recognize this necessity, thus
degrading the potential for digital geoscientifi c progress. Efforts
are under way to help bridge this gap, and to make digital data
management more than just an unfunded mandate in the digital
world. Earthcube (NSF, 2013) is an example of such an effort; it
attempts to bring together geologic experts with computer sci-
entists to fi nd effective solutions for problems inherent to digital
geoscientifi c data management. The goal is to develop mecha-
nisms by which the National Science Foundation can make such
digital data management a fundamental part of all geologic re-
search that they fund, without making that management a sweep-
ing, unfunded mandate.
Interoperability of the Vocabulary and Structure of
Digital Geologic Data
Conceptually, interoperability is the attempt to make infor-
mation accessible to as broad an audience as possible, without
sacrifi cing any data integrity. Traditional paper geologic maps
and accompanying textual documents once comprised the rec-
ord in which geologic mappers described and stored geologic
ndings. In a modern computing environment, geologic data are
managed in a digital database, a group of shapefi les, or any num-
ber of other formats. This introduces new problems for geologists
to deal with: Which digital format should be chosen? Will these
formats persist indefi nitely? How does a chosen format affect
data accessibility? The foregoing questions are at the core of the
issue of interoperability.
Through years of working with and creating paper maps,
geologists have been solving some of the fundamental issues of
interoperability. They have defi ned a set of conventions, or stan-
dards, which allowed for a common framework for communicat-
ing mapped geologic information in expected and understandable
ways. Many of these conventions are cartographic in nature, and
a few examples include contacts represented as solid lines, tri-
angular teeth on a line representing a thrust fault, or simply that
different colored areas represent exposure of different types of
rocks on Earth’s surface (FGDC, 2006). However there are often
issues of non-interoperability. Consider the classic issue of the
“boundary fault,” a false contact between two adjacent maps in
which identical geologic units are characterized differently. In
some cases, boundary faults may refl ect strongly different in-
terpretations on either side of an arbitrary boundary, but more
commonly they refl ect nonstandard vocabularies for naming
and describing map units. Standard vocabulary has been a per-
sistent issue in geologic research and data characterization for
years, and efforts to generate unifi ed stratigraphic nomenclature
are an ongoing topic of concern (e.g., Soller, 2009). Terminology
issues pervade geological science, from descriptions of a rock
to naming landscape-scale features. Clearly, we need a common
and fl exible language with which to describe Earth. Descriptions
and interpretations of rocks, structure, and geologic processes
in new and unexpected ways are fundamental to the progress of
geology as a science and require a growing, adjustable, and ever-
expanding vocabulary.
New technologies can help unify geologic vocabularies
(e.g., Durbha et al., 2009), but the abundance of available data
120 House et al.
formats presents a unique interoperability problem. Digital data
formats require interpretation by some piece of software, and not
all formats can be read by all software. Imagine one geologist
who uses expensive, proprietary software and associated data
formats to store their geologic map data. Users without access to
that software are immediately unable to view, critique, consume,
or expand on those data. A particularly frustrating issue arises
when a new application discontinues support for or does not sup-
port an established data format, leaving important data at risk of
being lost. If we assume a situation in which researchers have
agreed on a common data format and overcome these obstacles,
ensuring fl exibility in the way information is structured within
that data format presents another layer of complexity. A com-
mon example is when a geologist fi nds a useful data set, only to
learn that it includes a table with incomprehensible column head-
ings, or complex and indecipherable encodings of information
in any given cell. Without prior knowledge or detailed ancillary
information describing the structure of a data set, one geologist is
often unable to interpret the data produced by another.
Cartographic standards are required for some level of inter-
operability across paper geologic maps; likewise, the develop-
ment and adoption of standards for encoding digital geologic
map data are required for digital interoperability. Such standards
are diffi cult to produce because they must strike a balance be-
tween standardization and fl exibility. As in the case of standard-
ized vocabularies, strict, immutable data formatting hinders a sci-
entist’s ability to encode new scientifi c innovation. However, a
lack of standardization means the data are more diffi cult to share
(Gahegan et al., 2009). Many efforts are under way to attempt to
build such standard data encodings for geologic map data (e.g.,
NCGMP09 [USGS, 2011]; FGDC Geologic Standards [FGDC,
2006]; and GeoSciML [Sen and Duffy, 2005]), and fi nding this
balance is a persistent point of concern. Generally, data standards
attempt to identify some core information content that is perva-
sive across all relevant data sets and provide strict encoding for
that content. The most successful attempts then provide rules and
conventions about how the standard should be “extensible” or
designed to include other aspects of the data set that perhaps are
not explicitly recognized during or that develop following the ini-
tial formulation of the standard.
Even an incredibly well-designed standard is only interopera-
ble if it is widely adopted. The adoption of a standard format is a
complicated issue: Software developers generally will not support
a standard unless there is a large body of data using it, and scien-
tists generally will not encode data in a standard format unless it
is relatively simple, fl exible with respect to data types and termi-
nology, and usable by a diversity of software packages. If these
criteria are inadequately met, many geologists may be inclined
to take an anachronistic approach (opt out) and choose instead
a poorly contrived digital database or even a paper map to man-
age geologic information. As a result, attempts at standardization
may have few adopters, and attempts to improve existing stan-
dards or develop better ones are pursued by only a small number
of researchers. However, once a geologist realizes that modern
practice requires digital information, the issue of interoperability
cannot be ignored, thus presenting an opportunity that allows for
vast improvement in scientifi c collaboration and progress.
Map Scale Extrapolation
The widening availability of high-resolution, seamless im-
agery of Earth’s surface, the accuracy of modern GPS devices,
and the ability to visualize digital map data at any scale present
the modern geologist with another new dilemma: At what scale
should mapping be done? In the predigital era, the scales chosen
for the USGS topographic map series presented a simple answer
to this question. Utilizing new, seamless base data, it is now pos-
sible to view or print a map at virtually any scale. High-resolution
imagery and incredibly detailed LiDAR images expose geologists
to features that may have previously been indiscernible. These
new data formats seem at fi rst to be extremely benefi cial. They
offer the ability to identify and visualize geologic features that
previously were too small to map, and they allow for geologically
meaningful criteria to be the basis for map scale. However, the
chosen scale of a mapping effort is constrained by cost-benefi t
considerations (Goodchild, 2011), and there are some pitfalls to
which the modern geologist must pay attention.
The “living geologic map” concept requires that the funda-
mental data behind these geologic maps reside in a managed digi-
tal format, and that portrayals of that data, be they paper maps,
downloadable data, or online mapping applications, are only
snapshots of the data at a particular location and scale. Thus, one
may believe that the data should then be as detailed as possible.
However, meeting that expectation is diffi cult for many reasons.
We are growing accustomed to software that allows us to zoom in
and out of our data sets and to view them at essentially any scale.
However, a geologic map is a complex, often scale-sensitive car-
tographic work in which the details of the topological relation-
ships between various points, lines, and polygons represent very
specifi c aspects of a complex geologic system.
Geologic map data are generally collected for portrayal at
particular scales, but strict adherence is rare; the consistency of
map scale varies according to geologic complexity and individ-
ual mappers’ preferences. Like all maps, geologic maps always
represent a very signifi cant amount of generalization. Geologists
strive to be objective in the portrayal of what is actually on the
ground, but they must always simplify, generalize, and extrapo-
late from a ground-truth that exists at 1:1 into a much smaller
scale that best conveys the geologic history of a given region.
Mapping performed with a specifi c scale in mind can only be in-
terpreted meaningfully when viewed from a relatively restricted
range of nearby scales. The fundamental complication relates to
the need for ways to generalize our data quickly and effi ciently.
If our data exist at 1:2000 scale, but we want to take a snapshot at
1:30,000 scale in order to encapsulate a complete geologic story
in a single image, we need an effi cient way to generalize that
large-scale data. Automated algorithms exist that can simplify
the network of geometries used to represent geologic features
Overcoming the momentum of anachronism 121
(Smirnoff et al., 2008). However, these algorithms often gener-
ate geometries that look unnatural, obscure or destroy important
topo logical relationships between geologic features, and gener-
ally do not produce acceptable, smaller-scale representations of
the geology of a region without additional, labor-intensive edit-
ing by a knowledgeable geologist.
The process of generalization involves not only simplifying
geometric representations of contacts, faults, and rock types ex-
posed between them, but it also involves a myriad of decisions
about which features are fundamental to illustrating the geologic
framework of a region and which are too insignifi cant to repre-
sent. This is not a new problem, but increasingly complex tech-
nologies have given us the ability to be increasingly objective in
our data collection, and our generalization procedures need to
improve in order to keep up. Generalization of paper geologic
map data did not involve automated algorithms that are some-
how inaccessible to modern digital environments. Generating a
1:100,000 scale map based on a set of 1:24,000 scale quadrangles
involved extensive redrafting and generalization. Such a proce-
dure can just as easily be accomplished in a digital environment.
As modern technologies evolve, we will come closer to generat-
ing digital data sets that are accurate at increasingly large scales.
However, we’ll always need to zoom-out from that data in order
to get the big picture, and, unfortunately, the generalization re-
quired to do so is not a simple mathematical simplifi cation of an
array of geographic coordinates. Geologic generalization requires
complex decisions and scientifi c interpretations that presently are
diffi cult to capture in any automated fashion. It is important not
to view this as a shortcoming of digital data collection, because
in reality what we are dealing with is the opportunity to be more
objective in our representations of ground-truth.
In an environment where geologic mapping is accomplished
with increasingly tight budgets by fewer and fewer individuals
and organizations, it is not practical to develop only intricate,
large-scale data that may not even be visible in a preferred or re-
quired portrayal. However, it is practical to work in a framework
that can accommodate such change should the time, funding, or
need arise. It is also important to clearly communicate the scale
limitations of existing and evolving data sets. In order to accom-
modate change, we need to transform our thinking of single-scale
paper maps as fundamental end states of map data and realize
that the concept of scale is far more fl exible now than in the pre-
digital era.
Geologic mappers are on the cusp of a new conceptual and
operational paradigm. This precarious position is infl uenced by
an increasing tide of high expectations from students, colleagues,
grantors, and anonymous end users of our data and ideas. The
complete process of geologic mapping from the fi eld to the offi ce
and then to the end user can be made more relevant, responsive,
instructive, and effi cient with the systemic adoption of new and
widely available methods that take advantage of technological ad-
vances. The geologic mapping community must work together in
transforming the means of data collection, compilation, integra-
tion, publication, and distribution of their efforts in order to keep
geologic mapping viable and relevant in the twenty-fi rst century.
Some existing geologic mapping practices support a mo-
mentum of anachronism that is fueled by a mixture of institu-
tional “habit,” lack of technical training, and lack of fi nancial and
technical support. In some cases, it may be a lack of interest or a
lack of awareness of potential demand. The revolution in digital
mapping is well under way, evolving and permeating culture and
science on every level. Opting out is foolish; deciding how to
opt in is challenging. Obviously, paper maps will not go away,
but they are merely derivative “snapshots” drawn from what is
ideally an actively evolving geologic database. This has always
been the case, except that in the predigital era, the evolving data-
base was in the minds, notes, and subsequent publications of geol-
ogists. Digital mapping technologies now offer unprecedented
potential for the timeliness of maps to keep pace with scientifi c
and geologic change. Paper maps will always be outdated upon
printing, particularly when they arise from a fertile scientifi c or
dynamic geologic environment, but modern technologies can
minimize obsolescence through data management strategies and
mechanisms that accommodate map updates; collaborative edit-
ing; and wide, open, and easy access.
Perceptions of the longevity of geological maps may be
grounded in an awareness of the history of the time-consuming
mechanical processes that once went into making them. Much
of this effort was traditionally expended in ensuring that a qual-
ity graphic product was developed that adhered to a high, insti-
tutional aesthetic standard. However, the emphasis needs to be
shifted to a digital product that can be resymbolized in ways that
best suit users’ needs, and can be shown on a base layer (with
high geospatial precision) with a particular thematic emphasis,
or shown in a novel combination with other data sources. Thus,
the new perception should be that geologic data are needed for
an array of applications that consume, analyze, and portray digital
data sets in ways that can be easily represented in printed form as
may be required; however, printing is no longer a fi nal step in the
mapping process. The geologic community needs to collectively
design a system (or systems) that allows maps to be updated and
distributed in accordance with discovery of errors, new ideas, new
needs, or new geology. Recent global lessons learned from earth-
quakes, tsunamis, landslides, land subsidence, volcanic activity,
and massive hurricanes and fl oods make this point emphatically.
The expanding arrays of digital technologies available
to geologic mappers do not obviate the need for paper map
products , but they do lessen the need for the time-consuming
development of highly stylized paper maps. The paper-focused
geologic map model is plagued by cost and time commitments
of map layout, editing, and production in the face of widespread
adoption of digital portrayals that can be generated by users of
geologic map data. Up-front demands for high-quality, well-
managed, and effi ciently distributed data may ultimately have a
stronger infl uence than demands for highly stylized cartographic
122 House et al.
products. As a community, geologic mappers and mapping
agencies need to address the imbalance in emphasis placed on
the production of highly stylized printed (or printable) objects
at the expense of peer-reviewed inter operable geologic data sets
that support a large range of carto graphic portrayals by capable
end users. In the interest of cost-effectiveness, heavily stylized
cartographic treatment should be reserved for maps of notable
and signifi cant general interest that are intended to serve an im-
portant display function (e.g., national parks and other critical
areas). Such products also must be fully supported by funding
and staff adequate to transform a perfectly functional geologic
map into a high-quality piece of cartographic art while maintain-
ing necessary support for the generation of basic geologic map
data in other areas. The promises, challenges, and demands of
the digital era thus re affi rm that the primary focus on creating
geologic maps should be on data quality, representation, manage-
ment, and distribution within a dynamic framework that enables
analysis and discovery while also promoting greater understand-
ing and dissuading misuse.
This contribution is a formal culmination and expansion of the
senior author’s past efforts (2007–2010) to promulgate these
and related ideas to the geologic mapping community via a
series of blogs focused on the theme of “digital geology for
analog geologists.” We thank Vic Baker for his encouragement
and patience in the development of this paper and Sue Beard
(U.S. Geological Survey) and Phil Pearthree (Arizona Geologi-
cal Survey) for their thoughtful reviews. The opinions, ideas,
and suggestions expressed herein are derived from the authors’
individual professional experiences with geologic mapping and
GIS in a wide range of environments and under the auspices
of diverse institutions. Please note that the increasing interest
in all aspects of digital mapping has resulted in a proliferation
of literature in a myriad of publication outlets, and we regret
the omission of any key references that some readers may be
surprised are not present. We would also like to note that the
multi-authorship of this paper grew out of a public discussion
on a well-known social media Internet platform, and its prepa-
ration took advantage of various other Web-based applications
that allow for online collaboration in real time.
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Printed in the USA
Overcoming the momentum of anachronism 125
Techniques of geologic mapping and geologic map creation have changed significantly from traditional paper-based methods. Geologic mapping and data collection in the field is now primarily facilitated by mobile devices and dedicated geologic mapping software. Geologic map production has become a fully integrated process, importing digital data from the field and making use of cartographic software, such as ArcGIS and Adobe Illustrator, to create interactive geologic map products. Dissemination of geologic maps incorporates several types of map products to support the variety of uses that practitioners have for geologic maps and field data. Some of these map products include: 1. layered PDF maps, where layers can be toggled to show different map components; 2. Google Earth KML and KMZ files that can be viewed in the virtual 3D terrain of the geobrowser; and 3. GIS geodatabases that include not only the geologic map interpretation of a field area but also the primary field data. Geologic field data should also be archived in community databases, such as, so that future field workers can access and validate the data in their projects. This modern approach to creating geologic maps is highlighted in a case study from the lakes region of western Ireland, where undergraduate geoscience students have used digital mapping techniques in field exercises for several years. A brief discussion of the history of digital field mapping and map creation sets the stage for a discussion of modern techniques. Current best practices are highlighted for field mapping and data collection, geologic map creation, dissemination of map-related products, and archiving of data and products.
Full-text available
The phenomenon of volunteered geographic information is part of a profound transformation on how geographic data, information, and Knowledge are produced and circulated. This chapter begins by situating this transition within the broader context of an exaflood of digital data growth. It considers the implications of VGI and the exaflood for further time-space compression and new forms and degrees of digital inequality. We then give a synoptic overview of the content of this edited collection and its three-part structure: VGI, public participation, and citizen science; geographic Knowledge production and place inference; and emerging applications and new challenges. We conclude this chapter by discussing the renewed importance of geography and the role of crowdsourcing for geographic Knowledge production. © 2013 Springer Science+Business Media Dordrecht. All rights reserved.
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Geoscience students often have difficulty interpreting real-world spatial relationships from traditional two-dimensional geologic maps. This can be partly addressed with direct, tactile field experiences, although three-dimensional (3-D) cognition can still be hampered by incomplete exposure of all spatial dimensions. Many of these barriers can be overcome by incorporating computer-based, virtual 3-D visualizations within undergraduate field-oriented curricula. Digital field equipment is fast becoming a standard tool in environmental, engineering, and geoscience industries, in part because of the increased accessibility of ruggedized computers equipped with global positioning system (GPS) receivers. Handheld computers with geo graphic information systems (GIS) software record and display data in real time, which increases the accuracy and utility of draft field maps. New techniques and software allow digital field data to be displayed and interpreted within virtual 3-D platforms, such as Google Earth. The James Madison University Field Course provides a field geology curriculum that incorporates digital field mapping and computer-based visualizations to enhance 3-D interpretative skills. Students use mobile, handheld computers to collect field data, such as lithologic and structural information, and analyze and interpret their digital data to prepare professional-quality geologic maps of their field areas. Student data and maps are incorporated into virtual 3-D terrain models, from which partly inferred map features, such as contacts and faults, can be evaluated relative to topography to better constrain map interpretations. This approach familiarizes students with modern tools that can improve their interpretation of field geology and provides an example of the way in which digital technologies are revolutionizing traditional field methods. Initial student feedback suggests strong support for this curriculum integrating digital field data collection, map preparation, and 3-D visualization and interpretation to enhance student learning in the field.
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This article focuses on the representation of physical places on the Internet or what we term cyberscape. While there is a wide range of online place-related information available, this project uses the metric of the number of user-generated Google Maps placemarks containing specific keywords in locations worldwide. After setting out the methods behind this research, this article provides a cartographic analysis of these cyberscapes and examines how they inform us about the material world. Visibility and invisibility in material space are increasingly being defined by prominence, ranking, and presence on the Internet, and Google has positioned itself as a highly authoritative source of online spatial information. As such, any distinct spatial patterns within uploaded information have the potential to become real and reinforced as Google is relied upon as a mirror of the offline world.
Full-text available
Over the past three years we have successfully incorporated and evaluated the use of GeoPads in field geology courses offered at the University of Michigan's Camp Davis, near Jackson, WY; a GeoPad is a ruggedized Tablet PC equipped with Geographic Information System (GIS), Global Positioning System (GPS), wireless networking, electronic notebook and other pertinent software. The use of GeoPads has significantly enhanced our field exercises and excursions, for both students and instructors. For example, using GeoPads to teach field geology not only supports the traditional approaches and advantages of field instruction, but also offers important benefits in the development of students' spatial reasoning skills. Students are able to record observations and directly create geologic maps in the field, using a combination of pen-enabled GIS tightly integrated with a digital field notebook. The use of intuitive, free-hand data entry is a crucial advantage afforded by the Tablet PC. Overall, this arrangement permits students to record, analyze, and manipulate their data in multiple contexts and representations – while still in the field – using both traditional 2-D map views, as well as richer 3-D contexts. Such enhancements provide students with powerful exploratory tools that aid the development of spatial reasoning skills, allowing more intuitive interactions with 2-D representations of our 3-D world. Additionally, GIS-based mapping enables better error-detection, through immediate interaction with current observations in the context of both supporting data (e.g., topographic maps, aerial photos) and students' ongoing observations. This approach also provides students Knoop, Peter A., and van der Pluijm, Ben (2006) GeoPad: Tablet PC-enabled Field Science Education. In: The Impact of Pen-based Technology on Education: Vignettes, Evaluations, and Future Directions; editors: Dave Berque, Jane Prey, and Rob Reed. Purdue University Press. 200pp. with experience using tools that are increasingly relevant to their future academic or professional careers. The approach described herein is easily adoptable through its use of readily-available, off-the- shelf Information Technology (IT). It is also generally applicable to education and research in many traditionally non-IT-savvy science domains, in addition to geology, such as archeology, biology, sociology, natural resources, and environmental sciences.
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We integrated high-resolution bare-earth airborne light detection and ranging (LiDAR) imagery with field observations and modern geochronology to characterize the Tahoe-Sierra frontal fault zone, which forms the neotectonic boundary between the Sierra Nevada and the Basin and Range Province west of Lake Tahoe. The LiDAR imagery clearly delineates active normal faults that have displaced late Pleistocene glacial moraines and Holocene alluvium along 30 km of linear, right-stepping range front of the Tahoe-Sierra frontal fault zone. Herein, we illustrate and describe the tectonic geomorphology of faulted lateral moraines. We have developed new, three-dimensional modeling techniques that utilize the high-resolution LiDAR data to determine tectonic displacements of moraine crests and alluvium. The statistically robust displacement models combined with new ages of the displaced Tioga (20.8 +/- 1.4 ka) and Tahoe (69.2 +/- 4.8 ka; 73.2 +/- 8.7 ka) moraines are used to estimate the minimum vertical separation rate at 17 sites along the Tahoe-Sierra frontal fault zone. Near the northern end of the study area, the minimum vertical separation rate is 1.5 +/- 0.4 mm/yr, which represents a two-to threefold increase in estimates of seismic moment for the Lake Tahoe basin. From this study, we conclude that potential earthquake moment magnitudes (M-w) range from 6.3 +/- 0.25 to 6.9 +/- 0.25. A close spatial association of landslides and active faults suggests that landslides have been seismically triggered. Our study underscores that the Tahoe-Sierra frontal fault zone poses substantial seismic and landslide hazards.
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A long-standing question in lava flow studies has been how to infer emplacement conditions from information preserved in solidified flows. From a hazards perspective, volumetric flux (effusion rate) is the parameter of most interest for open-channel lava flows, as the effusion rate is important for estimating the final flow length, the rate of flow advance, and the eruption duration. The relationship between effusion rate, flow length, and flow advance rate is fairly well constrained for basaltic lava flows, where there are abundant recent examples for calibration. Less is known about flows of intermediate compositions (basaltic andesite to andesite), which are less frequent and where field measurements are limited by the large block sizes and the topographic relief of the flows. Here, we demonstrate ways in which high-resolution digital topography obtained using Light Detection and Ranging (LiDAR) systems can provide access to terrains where field measurements are difficult or impossible to collect. We map blocky lava flow units using LiDAR-generated bare earth digital terrain models (DTMs) of the Collier Cone lava flow in the central Oregon Cascades. We also develop methods using geographic information systems to extract and quantify morphologic features such as channel width, flow width, flow thickness, and slope. Morphometric data are then analyzed to estimate both effusion rates and emplacement times for the lava flow field. Our data indicate that most of the flow outline (which comprises the earliest, and most voluminous, flow unit) can be well explained by an average volumetric flux ∼14–18 m3/s; channel data suggest an average flux ∼3 m3/s for a later, channel-filling, flow unit. When combined with estimates of flow volume, these data suggest that the Collier Cone lava flow was most likely emplaced over a time scale of several months. This example illustrates ways in which high-resolution DTMs can be used to extract and analyze morphologic measurements and how these measurements can be analyzed to estimate emplacement conditions for inaccessible, heavily vegetated, or extraterrestrial lava flows.