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The author proposes scientific recognition of an existing, previously undefined and unnamed global feature. Aquaterra is suggested as the new name for the lands that were alternately exposed and inundated as ice sheets advanced and retreated over the past 120,000 years. The vertical amplitude of sea level change amounts to 130 meters, and the aggregate global area of aquaterra equates to the continent of North America. The time period coincides with the total span during which modern humans are known to have existed.
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ABSTRACT.The author proposes scientific recognition of an existing, previously unde-
fined and unnamed global feature. Aquaterra is suggested as the new name for the lands
that were alternately exposed and inundated as ice sheets advanced and retreated over
the past 120,000 years. The vertical amplitude of sea level change amounts to 130 meters,
and the aggregate global area of aquaterra equates to the continent of North America.
The time period coincides with the total span during which modern humans are known
to have existed. Keywords: aquaterra,continental shelf,ice ages.
Many times in the past 120,000 years, continental ice sheets advanced (Pel-
tier 1996; Clark and Mix 2002; Carlson and Clark 2012), and the world ocean
dropped as low as 125 meters below its current level (Frenzel 1973; Fleming and
others 1998; Fleming 2000; Siddall and others 2003; Milne and others 2005; Pel-
tier and Fairbanks 2006; CSIRO 2009). Many times, ice sheets retreated and the
ocean rose, once reaching about 5meters above its current level (Lambeck and
Chappell 2001; CSIRO 2009). Thus, there exists a vast earth feature, equivalent
to North America in size (Table 1), which transforms back and forth among
upland, wetland, and seafloor. The ocean gives and takes like a vast millennial
tidea long-term, irregular cyclethat has persisted for hundreds of thou-
sands of years and continues today (Douglas 1997; Kemp and others 2011; Lev-
itus and others 2012; Moore and others 2013). Spanning much of the
continental shelf and a small rim of the world’s present coastal lowlands, the
feature remains unnamed, though sizable parts of it are named (Beringia,
Doggerland, Sundaland, and Sahul), and the submerged portion is mostly
unexplored at fine scale. Globally, aquaterra favors the tropics and mid-lati-
tudes (Arctic, 17 percent; northern mid-latitudes, 34 percent; tropics, 38 percent;
southern mid-latitudes, 10 percent; Antarctic, 1percent) and thus clearly would
have been the most desirable place for people to live during the ice ages.
Knowledge of its existence is owed to a handful of geologists, oceanographers,
and other physical scientists who meticulously recorded the evidence of sea
level rises and falls and glacial advances and retreats, but the physical and
human implications of their discovery hardly have been touched.
*I am deeply indebted to Dawn Wright who reviewed two drafts of this paper, one many years ago and one
recent, and gave invaluable advice. I fondly recall many enlightening conversations with Jules W. Delambre
who lived with an abiding interest in the land I call aquaterra and died in 2007 without publishing his
intriguing work: “Beyond land bridges: Exploring the effects of changing sea levels on man during the last ice
age,” presented to the Kentucky Academy of Science on November 21,1986. I appreciate the review and com-
ments of Craig E. Colten, Barry Eakins, and unidentified peer reviewers, as well as the editorial guidance of
Bimal Paul and Peter Lewis. I thank Ed Martinko, Director of the Kansas Biological Survey, for support and
Jerry Whistler for providing cartographic assistance. Most of all, I appreciate and acknowledge my continuing
conversation with Jeffrey R. Dobson, my partner in this quest for two decades and my brother for even
kDR.DOBSON is professor of geography at the University of Kansas, Lawrence, Kansas 66045;
Geographical Review 104 (2): 123138, April 2014
Copyright ©2014 by the American Geographical Society of New York
Fifteen years ago, I proposed naming this global feature “aquaterra” and
urged its exploration (Dobson 1999; Dobson and Dobson 1999). It is the tradi-
tional role of geographers to identify, name, define, and formalize earth
features, just as biologists do for new plant and animal species. The practice
dates from the age of exploration and earlier when new features were added
routinely. The first modest step after discovery, then and now, is to give each
place a name, as Martin Waldseem
uller did when he defined South America as
a continent surrounded by ocean and named it America in 1507 (Wald-
uller 1507; Lester 2009). The next stage is detailed exploration, and the
final stage is scientific investigation. At present, aquaterra is so poorly under-
stood that it might well be labeled “aquaterra incognita,like “terra incognita”
(remote, unknown landmasses) in the early days of terrestrial exploration. Like
them, it is ripe for exploration.
In this essay, I further define aquaterra, offer a rationale for its recognition,
and suggest an exploration strategy. The name acknowledges its unique charac-
ter due to the fact that for thousands of years at a stretch it is covered by water
(aqua) and for thousands of years it is exposed as land (terra). This name
avoids any presentist terminology that would view it as submerged land, rising
water, or any other characterization of its present position in the cycle.
Detailed definitions and territorial geographies of aquaterra will facilitate
studies of physical and human processes during the Late Pleistocene ice ages.
Human migration, for example, can be understood better when the entire
“playing field” is known. Human evolution, demic expansions, and the
peopling of landmasses can be understood better if all exposed landforms are
documented, opening to investigation such issues as sighting distances from
island to island (Cavalli-Sforza 1993). Studies of the diffusion of material cul-
ture can be greatly improved by better understanding of explicit pathways
Above current sea level 1-5m17 7.0
At current sea level 020.9
Below current sea level -125 to -1m225 92.1
Total -125 to +5m245 100.0
Continental shelf
Overlapping aquaterra -125 to 0m228 84.1
Below aquaterra -200 to 0126 m43 15.9
Total -200 to 0mB 271 100.0
North America (for reference) 243
*In 100,000s of square kilometers.
Source: Calculated by author from Eakins and Sharman (2012, Table 1).
across aquaterra and advancements within it (Gamble 2013). Island ecology can
be understood as a factor in speciation once missing islands are identified.
The greatest justification, however, is the simple fact that so little is known
about the seacoast where a significant portion of humankind surely dwelled for
the better part of 120,000 years. The most startling fact about aquaterra is how
long various depths were exposed without interruption (sea levels based on
Gallup and others 1994; Lambeck and Chappell 2001; Commonwealth Scientific
and Industrial Research Organisation (CSIRO), 2009). Its upper zone, 25
meters deep, was exposed continuously from about 115,000 BP to 10,000 BP
(Figure 1). Surely this coastal zone that persisted for an uninterrupted period of
105,000 years (88 percent of the time that modern humans are known to have
existed) may have played a vital role in human evolution. For 60,000 years
before 12,000 BP, it never rose above -68 meters. For 35,000 years before 15,000
BP, it never rose above -85 meters. Even at 100 meters depth, the land was
exposed continuously for 12,000 years, more than twice the time span of all
recorded history. These are vast time periods during which much evolution,
physical and cultural, could have occurred and vast territories where people
could have thrived always in relative prosperity compared to farther inland.
Nomenclature and regionalization are essential steps to facilitate communi-
cation, awareness, and action:
CommunicationA primary purpose of this paper is to ignite a dialogue
that will generate support throughout the scientific community for the explora-
tion and scientific investigation of aquaterra. Yet, it is difficult even to discuss the
place without appropriate terminology. Customary terms such as “land bridge”
may serve well for local features, but fail to convey the regional and global extent
of vast coastal plains now submerged. Associating the global feature with a spe-
cific name, such as aquaterra, will focus and clarify the dialogue.
FIG.1—Sea level change since the dawn of modern humans. Sea level sources: CSIRO 2009;
and Lambeck and Chappell 2001.
AwarenessGeography, history, anthropology, archaeology, geology,
biology, and myriad other disciplines are influenced, knowingly or unknow-
ingly, by the existence of aquaterra. Having a proper name, definition, and
chronology will provide a common frame of reference for all disciplines.
ActionExploration and research are essential. Better communication
and awareness of aquaterra’s physical and cultural realities will, I hope,
motivate scientists of many disciplines to explore, investigate, examine, and
seek understanding.
Geographers, cartographers, and oceanographers need to define this feature at
least as rigorously as the continents traditionally have been defined. Aquaterra
is a global landmassa feature as distinctive as, for example, the continental
shelf, the Mid-Oceanic Ridge, the Russian steppe, the Andean mountains, or
any individual continent. Aquaterra occupies the upper majority of the conti-
nental shelf and the lower fringe of the current coastal plain of every continent
and island (Figure 2). Over thousands of years, it is at times a vast coastal low-
land; a vast shallow sea; and, in transition, a coastal wetland. Its size22.5mil-
lion square kilometers (Table 1; or more than 21.0million square kilometers in
Fairbridge 1982; Flemming 1985)is as great as that of some continents, but it
is not properly a continent due to its discontiguous dispersal about the globe.
All landmasses are defined by time as well as space. This principle is obvi-
ous for paleogeographic configurationsPangaea, Gondwanaland, Laurentia
and applies to the current continents as well. Even in previous geologic eras,
sea level rose and fell due to climate change (Jacobs and Sahagian 1993).
Implicitly, the definition of North America, for instance, refers to the present;
to an unspecified past when the current configuration of cratons, shields, terr-
anes, and sedimentary beds were assembled by geologic forces; and to an
unspecified future when the current configuration surely will evolve into some
distinctly different configuration. The seaward extent of the continental shelf is
FIG.2—Global distribution of aquaterra, based on current bathymetry, ETOPO1-Ice Surface
Data, with no adjustments for eustatic seafloor changes. (Cartography by Jerry Whistler, Kansas
Biological Survey, University of Kansas, using the Mollweide Equal Area Projection).
defined by a bathymetric contour, typically 200 meters deep, but the location
of that boundary is determined by slope and thus in many locations is rela-
tively insensitive to changes in sea level. As Michael Summerfield (1991,34)
explained, a cumulative frequency distribution of global elevation/bathymetry
“produces a hypsometric curve which...suggests that the true break between
the continents and oceans lies not at present mean sea level but some 200
meters or so lower.”
Aquaterra’s defined space is a function of time. I propose bounding it by
the highest and lowest sea levels of the past 120,000 years. This covers the best-
documented cycles of rise and fall and also the entire span of time during
which modern humans, physically identical to humans of today
, are known to
have existed. Excellent data are available for the most recent sea level rise,
based primarily on analysis of Barbados corals which indicate lows of -120
meters at 17,000 years (Fairbanks 1989) and -125 meters at 21,800 years (Peltier
1994). Some models have predicted levels as low as -135 meters at the Last
Glacial Maximum (Yokoyama and others 2000; Lambeck and others 2002; Pel-
tier 2002) or even -140 meters (Lambeck and Chappell 2001; CSIRO 2009), but
I have chosen to use the more conservative consensus of -125 meters (Fleming
et al., 1998; Fleming 2000; Siddall et al., 2003; Milne et al., 2005; Peltier and
Fairbanks 2006). Earlier Pleistocene ice ages produced even larger modulations,
but I have chosen to emphasize the human connection. Stringer and Gamble
(1993) studied human evolution in relation to glacial cycles inferred from heavy
oxygen isotope (
O) concentrations in marine sediment cores. William Calvin
speculated about the effects of glacial advance and retreat on development of
the human brain (Calvin 1990).
Aquaterra’s defined space is a function of scale. Globally at present, the sea-
ward boundary can be ascertained worldwide at one to twelve kilometers reso-
lution based on global bathymetry data developed by Walter Smith and David
Sandwell, the finest available bathymetric data for the ocean as a whole (Smith
and Sandwell 1997). ETOPO1bathymetry data (Amante and Eakins 2009,
Eakins and Sharman 2012) at one arc-minute resolution are produced by the
National Oceanic and Atmospheric Administration (NOAA) from satellite
altimetry and ship soundings and can be obtained readily from the National
Geophysical Data Center (NGDC) (Smith and Sandwell 1997). Finer resolution
data are available for certain countries (notably the coasts of the United States,
Australia, France, and the United Kingdom) as well as major sea-transportation
corridors elsewhere.
Globally, aquaterra’s inland boundary is imprecise. The Shuttle Radar
Topography Mission (SRTM) provides digital elevation data at 90 meters hori-
zontal resolution for all lands between about 60°N latitude and 56°S (Farr
and others 2007), but its vertical resolution (absolute height error as great as 16
meters) renders it inadequate for this purpose. Even the much finer U.S.
National Elevation Dataset (NED) has a root mean square error (RMSE) of
2.44 meters or about half the sea’s maximum elevation above current sea level
at 120,000 years ago. The very shallow zone (0to -10 meters) is especially diffi-
cult to register due to the challenges of converting among diverse terrestrial
and marine datumsthat is, elevation versus bathymetry.
Aquaterra’s defined space is locally uncertain due to the dynamics of coastal
landforms. The precision of the boundary depends on a thorough understand-
ing of erosion/deposition, seismic, tectonic, and eustatic processes over the past
120,000 years. Changes in global sea level (eustasy) shift massive weights of
water. Transgressions during periods of rising sea level increase the load;
regressions during periods of falling sea level reduce the load. The resulting
changes in eustatic pressure can cause significant uplifting or subsidence of
landforms (isostacy) depending on the slope and load-bearing strength of
underlying geologic structures. Coastal landforms occasionally undergo sub-
stantial alterations due to earthquakes and other seismic events caused by
changes in eustatic pressure or by deeper tectonic forces. Notable examples
include the Greek city of Helike which disappeared into the Gulf of Corinth in
373 BC (Soter and Katsonopoulou 2011) and Port Royal, Jamaica, which disap-
peared into the Caribbean Sea in 1692 (Hamilton 2005). When ancient ruins
are found, there is a tendency to dismiss them as subsidence, but scientists
conduct rigorous analyses to determine whether or not subsidence has
In some areas, erosion, deposition, subsidence, and tectonic activity have
raised or lowered land, producing counterintuitive results. Submerged areas
near current shorelines, for instance, may actually have been exposed when the
sea level was higher. Conversely, exposed areas near current shorelines may
have been submerged when the sea level was lower. Even more dramatically,
deltas, barrier reefs, wetlands, and lowland vegetation may have encroached
seaward so that sizable areas of aquaterra are now obscured by land rather than
water. The Nile and Mississippi deltas are dramatic examples. High-latitude
coasts are even more complex due to ever-changing ice cover and isostatic sub-
sidence and uplift (glacial “rebound”).
A long-term goal and major challenge of exploration should be to regional-
ize aquaterra with reference to three-dimensional space and time. In any given
era, aquaterra is either fully inundated during periods of maximum transgres-
sion, as it nearly is today; fully exposed as it was during the maximum regres-
sion 21,800 years ago; or partially inundated and partially exposed.
Regionalization thus depends on creating a reliable chart of dates and corre-
sponding mean sea levels over the past 120,000 years. It is essential, however,
to advance far beyond mere outline. Geographers, cartographers, oceanogra-
phers, and others should map and describe aquaterra’s physical geography,
emphasizing the lands exposed at any given time. Where were its rivers, estuar-
ies, and wetlands? Surely, such water features were focuses of biological activity
and human settlement then as in later historic times. Where were its uplands?
Surely, elevated areas would have served humans and animals alike as refuges
from flooding, and the theoretical maximum local relief within aquaterra is 125
meters. Where were its distinctive landforms? Waterfalls twice as high as Niag-
ara, cliffs as high as the Hudson River Palisades, and arches as high as Rainbow
Bridge, in Utah, conceivably could have existed there and may have been val-
ued in religious or secular ways.
The exposed portion of aquaterra is familiar territory, comprising the coastal
lowlands of every continent and island that modern inhabitants can see, sense,
map, and investigate. The currently submerged portion, however, is the least-
known zone on earth. It is, indeed, less familiar than the surfaces of the Moon
and nearest planets. For comparison, we Earthlings have imaged the surface of
Mars and Venus at 122 meters resolution, yet we have comprehensively mapped
aquaterra’s bathymetry only at one to ten kilometers resolution, and we’ve
imaged hardly any of the submerged portion. This submerged portion can be
further subdivided into a shallow plain less than 50 meters deep, which can be
explored readily by divers, and a deeper plain from 50 to 125 meters, which is
profoundly unknown. Even deep-ocean bottoms are better known due to
explorations in support of submarine operations during the Cold War because
“Blue Ocean” warfare focused primarily on depths below 185 meters.
Another reason for the dearth of information is the difficulty of measuring
bathymetry in shallow seas. It is actually easier to measure deep oceans than
shallow seas due to the inherent geometry of active sensors such as sonar. A
signal is emitted from a ship’s sounding device, and the echo returns to a recei-
ver. This limits the angle of incidence to 45
, so that the swath equals the depth
times two. Thus, in deep ocean the swath may be a kilometer or more, while
in aquaterra it is never more than 250 meters. Such a narrow swath means that
a comprehensive survey of any given area requires many tracks. Prior to the
advent of the Global Positioning System (GPS), cartographic control was extre-
mely imprecise. Even with GPS-controlled navigation of survey ships, synthesiz-
ing many narrow tracks into continuous map coverage is technically
demanding. It can be done readily in many coastal areas based on multibeam
sonar sensors and differential GPS, but global coverage is infeasible at present.
Satellite altimetry, based on highly sensitive measurements of gravity, has
replaced sonar as the technique of choice for global bathymetry, but the results
are imprecise for the continental shelf (Smith and Sandwell 1997). The satellite’s
sensor collectively measures the gravity of the total column of core, mantle,
crust, water, and atmosphere beneath each point in its path. An algorithm then
estimates the partial gravity attributable to each component and divides mass
by density to estimate height. In deep ocean, the crust is thin and contributes
relatively little to total gravity, thus imposing relatively little uncertainty on the
water component of the column. Beneath the continental shelf, however, the
crust is thick and also may contain irregular geologic structures of unknown
density, thus imposing greater uncertainty on the water component. Also, in
extremely shallow areas shoals interfere with the sensor’s measurements.
The past two decades have seen remarkable advances in measuring shallow
ocean bottom at high resolution through technologies such as autonomous
underwater vehicles and airborne lidar bathymetry (ALB) (Klemas 2013). While
satellite sensing by ALB is technically feasible, investigators currently must rely
on custom surveys by aircraft, and no global database has yet been developed.
Direct visual or photographic observation of the lower plains of aquaterra
is hampered by darkness. Shallow areas can be observed in natural light, but at
100 meters depth light attenuation reduces visibility to 1percent of surface
intensity. Floodlights can be employed by deep divers or with cameras on sub-
mersibles and remotely operated vehicles (ROV) to illuminate features close at
hand, but dependence on active light sources limits perspective. The effect is
comparable to walking through a vast chamber with only a flashlight.
Ancient lost landsAtlantis, Shangri-La, Murediscovered in all their utopian
glory are standard fare of science fiction novels, movies, and television. Society
seems to yearn for some lost connection to an unreported past, yet science
offers little in that vein regarding aquaterra’s lost land, which is known with
certainty to have existed. Instead, conscientious amateurs amass enormous tro-
ves of evidence, only to analyze them with poor standards of proof. Surely it is
time for the scientific community to reclaim this (literal and figurative) terri-
tory, for critical analyses of its role in shaping the world we know today.
The geographical significance of aquaterra can best be understood though
modern analogies. Consider, for instance, how much land would be lost and
how many people would be displaced if the sea level rose another 125 meters
today. The Mississippi Valley would be filled as far north as Illinois, the Ama-
zon well into Eastern Peru, and the Ganges halfway across India.
Estimates of future sea level rises are, of course, much less than 125 meters
(Baker and McGowen 2012; Bromirski and others 2012; Powell and others 2012;
Abbott 2013; Bamber and Aspinall 2013; Moore et al., 2013; Parker and others
2013; Webb and others 2013). Rowley and colleagues estimate that a 5meter
riseequivalent to the maximum inundation at 120,000 BPwould inundate
2.0million square kilometers and displace 376 million people (Rowley and oth-
ers 2009). An extra single meter of rise, for a total of 6meters, would increase
those numbers to 2.1million square kilometers and 431 million people.
Thus far, I have defined aquaterra as a global earth feature in the realm of
physical geography. Here, I will explain how it differs from the continental
shelf and briefly address its human geography.
In territorial extent, aquaterra is similar to, but not synonymous with, the
continental shelf. Quantitatively, aquaterra occupies 84.1percent of the
continental shelf, plus more than 1.7million square kilometers of uplands and
wetlands above current sea level (Table 1). How does the continental shelf that
overlaps (22.8million square kilometers) differ from the part that does not? It
is tempting to say the deeper part (continental shelf below aquaterra) has never
been exposed, but again time is crucial. It has not been exposed for at least
140,000 years (Figure 1), whereas all of aquaterra has been exposed for at least
some of that time and part of it is still exposed today. Thus, aquaterra has
experienced terrestrial influences such as direct exposure to wind and rain, ero-
sion and sedimentation, vegetative succession, and human occupance. Addi-
tionally, certain processes that are not exclusively terrestrial, such as glaciation
and volcanic eruption, would have affected exposed portions of aquaterra in
very different ways than the submerged land. All of these influences are impor-
tant, but human occupance stands out as the most distinctive for how humans
impact the environment and for understanding human origins, both physical
and cultural. Conceptually, aquaterra is to geographical space what the Anthro-
pocene is to time (Crutzen and Stoermer 2000; Syvitski 2012). In both cases,
human occupance is the defining characteristic. Aquaterra was exposed directly
to Anthropocene influences in a terrestrial environment, while the rest of the
continental shelf was exposed mainly to secondary, aquatic influences.
Compare the most recent curve of sea level rise against the timeline of cul-
tural innovations (Figure 3), and you will find that much human progress
occurred while seacoasts were still quite low. It would not change the timeline
of human progress if, for instance, cities were found as low as -50 meters,
since Jericho is known to have existed when sea levels were that low. Similarly,
FIG.3—Timeline of major cultural innovations in relation to sea level rise over the past
18,000 years. Dates of cultural innovations are taken from various sources, either reputable web-
sites or journal articles, many of which differ regarding precise dates. Hence, they are for general
reference and not meant to be definitive.
a village at -90 meters would merely be contemporaneous with the first known
villages in the uplands. More exciting, of course, is the possibility that
precursors of major innovations may exist at even lower depths. One
intriguing possibility is pottery. It would not be surprising to find shards as
low as -120 meters, since pottery first appeared 18,000 years ago. It would be
remarkable, but not unreasonable, if precursors were found as low as -125
meters since the Venus of Dolnı
´Vĕstonice, Czech Republic, the first fired clay
object of any kind, dates much earlier at 27,000 years ago (Stringer and
Gamble 1993).
In terrestrial geography, world regions tend to be defined primarily by
human characteristics (cultures, religions, languages, and the like) with bound-
aries often demarcated by physical features (such as oceans and mountains).
Aquaterra’s unique hybridization of terrestrial and marine geography makes it
amenable to either human or physical regionalization. Certain portions of
aquaterra have been named, and their identities are primarily physical. Berin-
gia, for instance, is simply the portion that lies between Siberia and Alaska;
Doggerland is that which lies in the North Sea and Atlantic Ocean off Western
Europe; Sundaland is that which lies off Southeast Asia surrounding numerous
islands and including the Sunda Straight. At present, not enough is known to
say how they differed culturally from one another.
What is the potential for defining cultural regions throughout aquaterra?
Presently, researchers can infer a few likely characteristics based on the contem-
porary human geography of either adjacent coastal lands or suspected emi-
grants who arrived in other regions as their homelands were being submerged.
In both cases, present knowledge is inadequate, but recognition of aquaterra
will encourage new avenues of research that may yield sufficient knowledge
over time. The greatest need, however, is underwater archaeology in every por-
tion of aquaterra’s physical feature. Examples of successful searches include
physical evidence of rapid inundation of the Black Sea and associated cultural
artifacts found by William Ryan and Walter Pitman (2000) and various cul-
tural artifacts, including sunken ships, found by Robert Marx (1990).
A first step toward rational consideration of aquaterra could be enhanced com-
mitment to exploration of the shallow-ocean floor in its own right. In the pub-
lic mind, ocean exploration primarily means the water column per se and the
deep-ocean bottom. While such interest in the deep unknown is understand-
able and research there is vital and productive, there is an equal need to under-
stand the ocean bottom located closest to our own habitat. Not long ago, the
most conspicuous interest in shallow, underwater exploration was focused on
shipwrecks, especially treasure ships. Today, serious attention is paid to human
artifacts in shallow seas. Aquaterra can be a rallying cry to support and clarify
the efforts of dedicated underwater archaeologists such as those cited by Geoff
Bailey and Nic Flemming and more broadly to encourage all scholars interested
in studying human and biophysical developments from ancient to modern
times (Bailey and Flemming 2008).
One fruitful avenue of research will be to compare ancient maps and litera-
ture with ancient seacoasts. Conscientious amateurs already do so, but there is
a pressing need for serious, scholarly analyses. If early maps depict ancient
(lower) seacoasts with a precision that is not likely due to random chance, then
either the maps were made earlier than previously recognized or the maps are
based on originals passed down from earlier observers in graphic, written, or
oral form. (It would be unfair to let this topic pass without mentioning the
work of Charles H. Hapgood, who pioneered this type of study and is now
cited frequently in popular literature about Atlantis. It is worth noting that the
foreword of his book, Maps of the Ancient Sea Kings (1966), was written by
John K. Wright, one of the most respected geographers of the 20
Similarly, if ancient documents signal an awareness of sea level rise, then they
too may date from that earlier time or may result from corporate memory per-
sisting longer than previously acknowledged.
Statistics will be an important tool when comparing ancient maps to bathy-
metric contours, but a new statistic is needed for measuring probability-of-fit
(Dobson 2000). What is the probability that any observed similarity between
them is purely accidental? What is the probability that they were drawn inde-
pendently? These questions are analogous to the “torn dollar” puzzle, a long-
time staple of spy stories, in which a dollar bill is torn in half and later
rejoined to prove identity or association. The solution will involve moving the
two paths (representing linear map features in the general case or torn edges in
the analogy) to a common origin, rotating them to achieve the best fit, delimit-
ing the sets of all possible configurations and all possible intersections, con-
structing a probability surface, and calculating probabilities for exact and
inexact matches.
Another fruitful avenue will be to map human habitation sites into readily
accessible geographic information system (GIS) databases with systematic, com-
prehensive, and global coverage. It will be useful to map all purported under-
water structures at high precision with attributes and confidence levels. Indeed,
conscientious amateurs often claim to find pyramids, buildings, and roads.
Those claims should be subjected to rigorous confirmation or rejection based
on scholarly standards.
Ultimately, it will be essential to create 3-D geovisualizations of the land
that was lost, carefully noting each temporal phase of sea rise and fall.
These geovisualizations should be global in coverage and should meet the
highest standards of cartographers and geographers. The aquaterra quest will
be as challenging and rewarding as Marie Tharp’s quest to map and visual-
ize the ocean bottom (Felt 2012). In all likelihood, features will be found
that alter societal understanding of human evolution and cultural develop-
ment as dramatically as Tharp’s discovery of the Mid-Oceanic Rift altered
geologic theory, resulting in widespread acceptance of continental drift and
plate tectonics.
The quest to explore the oceans warrants a program as aggressive as the
space program that has constituted a significant portion of the U.S. federal
budget since the early 1960s. In 2000, President Clinton convened an Ocean
Exploration Panel of leading ocean explorers, scientists, and educators (NOAA
2012). The panel recommended designating a lead agency to champion the
cause of ocean exploration, establishing an Ocean Exploration Advisory Board,
funding ocean exploration at $75,000,000 per year, and convening a national
Ocean Exploration Forum. Subsequently, the White House and Congress desig-
nated the Department of Commerce, specifically NOAA, to fill that role. Since
then, NOAA’s Office of Ocean Exploration and Research (OER) has been a lea-
der and vocal advocate, but public enthusiasm and political support have been
weak. Funding for the first decade amounted cumulatively to only
$185,000,000, far below the panel’s recommended level, and present funding is
only $20,000,000 per year. In contrast, the National Aeronautics and Space
Administration’s (NASA) exploration budget for FY 2012 was $333,700,000 for
research and development, not including systems development and commercial
spaceflight (NASA 2013). Even from the most pragmatic, human-safety perspec-
tive, taxpayers would do well to recognize that they are more vulnerable to
unpredictable forces (tsunamis, seismic events, heat and water transfers to the
atmosphere) arising from the seafloor than from, say, asteroids hurtling in
from space. Add to that a deep, abiding interest in human origins, and there’s
a clear justification for massive funding.
Logically, NOAA and other ocean-exploration advocates need aquaterra (or
some other new and exciting theme) to stir public interest and broaden sup-
port within the scientific community. The panel’s report (NOAA 2012) clearly
places human artifacts within the program’s scope, and that can be a founda-
tion for exploring the human geography of aquaterra. Perhaps, for instance,
there will be major thrusts toward understanding what role the shallow seafloor
played in human evolution and cultural development, studying land/sea inter-
changes during the ice ages, and finding submerged settlements. The current
frame of reference consists of “archaeology” and “social sciences.” Perhaps soon
it will include “ice age,” “civilization,” “inundation,” or other related phrases
such as “sea level.” The first national Ocean Exploration Forum was held in
2013, and its report and strategic plan for 2020 will be published soon. I hope
the new Ocean Exploration Advisory Board will include a heightened focus on
aquaterra in future forums, reports, strategic plans, and the President’s
National Ocean Policy Implementation Plan.
Of course, massive funding is not likely to materialize anytime soon due to
the state of the economy and to the inordinate educational effort that will be
necessary to bring the populace and politicians onboard. Meanwhile, a low-cost
alternative could be a volunteered geographic information (VGI) approach in
which one or more aquaterra mapping centers are established to accept VGI
observations rigorously collected by boaters and divers, enter the observed
depths and features with attributes and confidence levels in a global GIS, and
verify through various means, such as cross-checking of multiple observations
or spot checking with purposeful expeditions.
The exploration and scientific investigation of aquaterra will require
extraordinary collaboration among geographers and oceanographers. Neither
profession alone is adequately equipped to address the dynamic, physical ocean
below sea level and the dynamic physical and human world above and beside
it. Geographers, for instance, are accustomed to mapping and analyzing road
networks and settlements, but not 3-D columns of ocean water. Oceanogra-
phers are accustomed to studying currents and corals, but not sequent occu-
pance by humans. Oceanographers chart, geographers map, and many
cartographic concepts differ between them. Geographers designed geographic
information systems (GIS) to suit their needs and have been using GIS inten-
sely for decades. Geographer and ocean scientist, Dawn Wright, chief scientist
of ESRI, personifies the type of collaboration that will be needed as she leads a
consensus-building forum on how ESRI’s ArcGIS should evolve to meet the
needs of oceanography (Wright 2002).
It is tempting to say unprecedented collaboration is needed between the two
disciplines, but that would ignore their common origin dating back to antiquity.
For thousands of years, the recognized experts on lands and oceans were called
geographers. In Russia even today, oceanography is one of several key disciplines
comprising the Faculty of Geography at Moscow State University, and joint
expeditions of geographers and oceanographers are widely reported. In the Uni-
ted States, oceanography developed as a separate discipline in the mid-19
tury. Matthew Fontaine Maury, today recognized as “the father of
oceanography,” named his seminal book The Physical Geography of the Sea (1855)
and personally served as vice president of the American Geographical Society
(AGS) in 1854 and 1855 and on the AGS Council from 1859 through 1860. Also,
from 1928 to his death in 1939, Charles R. Crane served on the AGS Council,
funding geographic causes and generously endowing Woods Hole Oceano-
graphic Institution. Hence, it is proper to say that geographers and oceanogra-
phers should collaborate again as they did in the past, and both should reach out
to a variety of complementary disciplines such as archaeology and geophysics.
First, however, the community of interested scholars will need to agree that
the feature exists and give it a name. Aquaterra will serve well.
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... After World War II, humans enhance their role as a keystone species to dramatically intensify their rate of environmental impact (Thomas 1956;Turner and others 1990;McNeill and Engelke 2014;Bjornerud 2018). For example, anthropogenic influences on climate change and sea-level rise have resulted in acknowledgement of previously unidentified global features, such as aquaterra, lands undergoing periods of exposure and inundation by the advance and retreat of sea level during the last 120,000 years (Dobson 2014). Technological innovations and information availability (i.e., publication outlets) also increase substantially. ...
... What are the different life cycles or morphologies of a human-environment time period? How do global environmental changes, such as sea-level rise, factor into periodization (see Dobson 2014)? ...
Full-text available
Concern about accelerating human impact on Earth systems coincides with discussion of adding a new proposed geologic epoch that would document the Age of Humans. This research contributes a human-environment timeline prototype. Time-period classification provides academics and citizens alike with a common temporal reference frame for discussion and further investigation. A hierarchical human-environment timeline was built from analysis of entries in four geographic encyclopedias. Through grounded theory, an open-ended, qualitative analysis of dates identified important events in the human-environment relationship and major ideas that shaped environmental perception. The resulting timeline prototype features a typology of periods based on five relative timescales: lengthy Durations, Duration Revolutions, intermediate-scale Scenes, Scene Transitions, and shorter Intervals. Four long-term Durations emerge: Survival (2,598,050 to 318,050 BCE), Adaptation (318,050 to 4,050 BCE), Keystone (4,050 BCE to 1945 CE), and Acceleration (1945 CE –). The timeline provides a foundation for further scholarly analysis and thinking.
... Coupled with the archaeological significance of these landscapes, is the recognition of just how much land has been lost to the sea over time, and the acknowledgement that this is neither a unilinear nor a final process (Dobson 2014). Whilst future sea-level rise is inevitable, the sea has not risen uniformly around the world. ...
Full-text available
Europe’s Lost Frontiers was the largest directed archaeological research project undertaken in Europe to investigate the inundated landscapes of the Early Holocene North Sea – the area frequently referred to as ‘Doggerland’. Funded through a European Research Council Advanced Grant (project number 670518), the project ran from 2015 to 2021, and involved more than 30 academics, representing institutions spread geographically from Ireland to China. A vast area of the seabed was mapped, and multiple ship expeditions were launched to retrieve sediment cores from the valleys of the lost prehistoric landscapes of the North Sea. This data has now been analysed to provide evidence of how the land was transformed in the face of climate change and rising sea levels. This volume is the first in a series of monographs dedicated to the analysis and interpretation of data generated by the project. As a precursor to the publication of the detailed results, it provides the context of the study and method statements. Later volumes will present the mapping, palaeoenvironment, geomorphology and modelling programmes of Europe’s Lost Frontiers. The results of the project confirm that these landscapes, long held to be inaccessible to archaeology, can be studied directly and provide an archaeological narrative. This data will become increasingly important at a time when contemporary climate change and geo-political crises are pushing development within the North Sea at an unprecedented rate, and when the opportunities to explore this unique, heritage landscape may be significantly limited in the future.
... Sea levels have been lower than present almost everywhere for 95 per cent of the last glacial-interglacial cycle ( Grant et al. 2014 ;Lambeck et al. 2014 ). During the Last Glacial Maximum (LGM), low sea levels exposed ∼20 million km 2 of new territory around the world's continental margins ( Dobson 2014 ;Spada and Galassi 2017 ), much of it offering some of the most attractive territory available for human settlement and dispersal ( Figure 1 ). This long period of low sea levels hides palaeoshorelines and coastal landscapes that likely contain some of the most important archaeological and palaeoenvironmental evidence for human developments during the past ∼125,000 years. ...
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In this paper we highlight the impact of sea-level change on the archaeological record of key developments in human history that took place during the late Pleistocene and the early Holocene. Before modern sea level became established from ∼7 ka onwards, most palaeoshorelines and large areas of coastal hinterland were exposed as habitable land and then drowned again by sea-level rise. We summarise the archaeological implications of this pattern and the conditions in which archaeological and geoarchaeological evidence from these submerged landscapes is preserved despite the potentially destructive erosional impact of sea-level rise. We provide examples of palaeolandscape reconstruction made possible through multi-disciplinary collaboration between archaeology and marine science, drawing on recent underwater research in the North Sea, the Red Sea and on the Cape Coast of South Africa, and discuss evidence of past human responses to sea-level change. We identify the types of modelling procedures that need to be developed to advance this field of research, emphasise the importance of inter-disciplinary collaboration involving two-way exchange of ideas and information between archaeology and marine science, and highlight the value of a long-term perspective in understanding the present and future human impact of sea-level rise.
... "Skyscrapers, air-space, mountains" and other focal points turn Western minds "up and out, by flight, adventures in outer space and of late, by climate change and other atmospheric preoccupations" (Hawkins 2020, 4). The Anthropocene literally grounds our gaze, disclosing previously unknown physical landforms like aquaterra, influenced by continuous advance and retreat of sea level during the last 120,000 years (Dobson 2014;Dobson, Spada, and Galassi 2020). Landscape ideas like aquaterra characterize the shifting Earth system setting and add dynamism that prior typologies lack, such as Humboldt's (1849) elevation-based classes of tierra caliente (hot land), templada (temperate), fr ıa (cold), and helada (frozen). ...
... This paper builds on three previous ones that establish the global context of Beringia and reveal spatio-temporal opportunities for human crossings. First, Dobson (Dobson 2014) emphasized the importance of aquaterra as a global feature and gave it a name. Aquaterra is the collective identity of all lands that were inundated and exposed repeatedly during the Late Pleistocene ice ages from the first appearance of modern humans through today. ...
... During the Last Glacial Maximum, sealevel dropped to -120 m 30,000 years ago and persisted at about that level for over 10,000 years, with a shorter episode of maximum lowering to -130 m at 20,000 years ago (Lambeck et al., 2014). The maximum area of land exposed on the continental shelf during this period is estimated at 22 million square kilometres around the world's coastlines (Dobson, 2014), equivalent to twice the area of the current European land mass between the Ural Mountains and the Atlantic Ocean. Between about 17,000 and 6000 years ago, sea-level rise progressively drowned this vast territory. ...
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This Special Issue brings together fourteen articles that present new methods, ideas, and approaches in the study of coastal prehistory with examples drawn from the Americas, Australia, Europe, Saudi Arabia, and South Africa. In this introductory overview, we set out the rationale for combining articles on shell middens and submerged landscapes and the underlying logic of the order in which we have chosen to present the articles. The sequence begins with studies of marine molluscs and moves progressively outwards from small-scale studies of midden composition to large-scale studies of submerged landscapes, and from land to sea. We summarise the contents of each article and highlight connections between them and similarities and contrasts. We conclude with some final comments about the relationship between on-land and underwater investigations and identify the taphonomic, formational and deformational histories of archaeological deposits, materials and landscapes, and the variable impact of sea-level change as unifying themes.
... Unfortunately, many planetary and astronomical factors contribute to aspects of climate-change that affect Brazil's coastline still remain unexamined [20]! Former landscapes that are currently classified as coastalscapes due to the Holocene post-Ice Age global mean sea-level rise have been referred to now by geographer Jerome E. Dobson as "Aquaterra" [21]. A region of the Earth-crust that is increasingly open to archaeological researchers, "Aquaterra" is a coastal region that is part strand and part seafloor. ...
Full-text available
p>This article provides an overview of the known current situation of Guanabara Bay with respect to its pervasive plastic waste pollution, continuing the paired authors' previous works. In addition, the study opens up a broader public discussion on the fundamentals of global degradation, proposing a review of environmental education curriculums including the correct appropriation of the concept of entropy among adults and young people as well. In this sense, the authors deepen the concept and emphasize the importance of considering it in critical reflections on our present-day and future worldly behaviors and actions. Lastly, the work provides some significant and important relevant data and useful references, tracing some lines of thought for building viable solutions, so that the reader can start or continue further studies on the topic addressed herein. Key-words: Guanabara Bay, entropy, plastic waste, environmental education, global degradation, consumerism. ====================================================================== O presente artigo fornece um apanhado geral da situação atual da Baía de Guanabara com respeito à poluição por resíduos plásticos, dando continuidade aos trabalhos anteriores dos autores. Além disso, o estudo abre uma ampla discussão sobre os fundamentos da degradação global, propondo uma revisão dos projetos de educação ambiental incluindo a apropriação correta do conceito de entropia por adultos e jovens. Nesse sentido, os autores aprofundam o conceito e ressaltam a importância de considerá-lo nas reflexões críticas sobre os nossos comportamentos e ações. Por último, o trabalho fornece dados e referências relevantes, traçando algumas linhas de pensamento para a construção de soluções viáveis, de modo que o leitor possa iniciar ou prosseguir estudos complementares sobre o tema. Palavras-chave: Baía de Guanabara, entropia, resíduos plásticos, educação ambiental degradação global, consumismo.</p
... Unfortunately, many planetary and astronomical factors contribute to aspects of climate-change that affect Brazil's coastline still remain unexamined [20]! Former landscapes that are currently classified as coastalscapes due to the Holocene post-Ice Age global mean sea-level rise have been referred to now by geographer Jerome E. Dobson as "Aquaterra" [21]. A region of the Earth-crust that is increasingly open to archaeological researchers, "Aquaterra" is a coastal region that is part strand and part seafloor. ...
Full-text available
This article provides an overview of the known current situation of Guanabara Bay with respect to its pervasive plastic waste pollution, continuing the paired authors' previous works. In addition, the study opens up a broader public discussion on the fundamentals of global degradation, proposing a review of environmental education curriculums including the correct appropriation of the concept of entropy among adults and young people as well. In this sense, the authors deepen the concept and emphasize the importance of considering it in critical reflections on our present-day and future worldly behaviors and actions. Lastly, the work provides some significant and important relevant data and useful references, tracing some lines of thought for building viable solutions, so that the reader can start or continue further studies on the topic addressed herein. Resumo: O presente artigo fornece um apanhado geral da situação atual da Baía de Guanabara com respeito à poluição por resíduos plásticos, dando continuidade aos trabalhos anteriores dos autores. Além disso, o estudo abre uma ampla discussão sobre os fundamentos da degradação global, propondo uma revisão dos projetos de educação ambiental incluindo a apropriação correta do conceito de entropia por adultos e jovens. Nesse sentido, os autores aprofundam o conceito e ressaltam a importância de considerá-lo nas reflexões críticas sobre os nossos comportamentos e ações. Por último, o trabalho fornece dados e referências relevantes, traçando algumas linhas de pensamento para a construção de soluções viáveis, de modo que o leitor possa iniciar ou prosseguir estudos complementares sobre o tema. Palavras-chave: Baía de Guanabara, entropia, resíduos plásticos, educação ambiental degradação global, consumismo.
... "Skyscrapers, air-space, mountains" and other focal points turn Western minds "up and out, by flight, adventures in outer space and of late, by climate change and other atmospheric preoccupations" (Hawkins 2020, 4). The Anthropocene literally grounds our gaze, disclosing previously unknown physical landforms like aquaterra, influenced by continuous advance and retreat of sea level during the last 120,000 years (Dobson 2014;Dobson, Spada, and Galassi 2020). Landscape ideas like aquaterra characterize the shifting Earth system setting and add dynamism that prior typologies lack, such as Humboldt's (1849) elevation-based classes of tierra caliente (hot land), templada (temperate), fr ıa (cold), and helada (frozen). ...
Full-text available
Drawing from early modern and contemporary geographic thought, this article explores how the premise of an Anthropocene (Age of Humans) can be used to reinforce enduring modes of human–environment thinking. Anthropocene dialogues build on insights posed by geographers of the eighteenth and early nineteenth centuries: unity of nature, humans as nature made conscious, humans as nature’s conscience, and time periods as devices for thinking about human–environment relations. Complementing these ideas, contemporary geographers are making compelling statements about the Anthropocene, affirming that interpretations of the proposed geologic time period differ according to socioenvironmental variables, geographic imaginations, local contexts, and critical perspectives. Three forms of human–environment thinking emerge from examining links between early modern geographers and current geographers addressing the Anthropocene: synthesis thinking, epistemological thinking, and ethical thinking. Connections across ideas concerning the Anthropocene and geographic thought will be strengthened by developing systematic chronologies of the human–environment relationship.
In this paper new palaeogeographic and archaeological data from the prehistoric cave Vela Spila on the island of Korčula in Croatia are combined with new realizations of two glacial isostatic adjustment models in order to present relative sea-level change scenarios confronting the inhabitants of the cave at different time slices and to show how they experienced and adapted to sea-level and climate change from the Late Pleistocene through the Holocene. Our results show that from the Late Upper Palaeolithic until the Mesolithic, humans in the study area would have experienced tens of metres of sea-level rise, at rates in some cases up to 12 mm per year, and, owing to the relatively flat morphology of the now submerged plains, hundreds of meters of horizontal coastline change in the plains to the north and south of the island. This evidence supports the hypothesis that the rapid loss of these plains likely contributed to the human abandonment of the cave after the Palaeolithic for about five thousand years, followed by significant changes in lifestyle and diet in the Mesolithic. Our results have important implications for the study of how past human groups, especially in vulnerable coastal areas, were affected by sea level, climate, and other environmental changes. Vela Spila represents a case study of how changing environment and rising seas can force significant alterations in human societies, even when there is no risk of inundation to settlement sites.
Full-text available
While the earliest continental ice sheets were gradually engulfing mountainous landmass of Antarctica, in Africa an undistinguished species of ape was evolving into the species that we now call man. Examination of oceanographic cores and the dating of sediments from around Antarctica show that the ice began to form about 5 million years ago. Later, ice sheets up top 3 kilometres thick also covered Greenland, Canada and Scandinavia, and extensive glaciers formed in the valleys of all the mountain ranges in the world. During the last 2 million years such vast accumulations of ice have covered the land and melted again about 20 times, each Ice Age lasting about 100,000 years.
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ABSTRACT Coastal ecosystems tend to be spatially complex and exhibit high temporal variability. Observing them requires the ability to monitor their biophysical features and controlling processes at high spatial and temporal resolutions, which can be provided by airborne remote sensors. High resolution satellite data are now also available, yet the finer resolution and frequent, flexible overflights offered by airborne sensors can be more effective in a wide range of coastal research and management applications, such as wetlands mapping, LiDAR bathymetry, and tracking coastal plumes, salinity gradients, tidal fronts and oil slicks. The airborne imagery is also very useful for the interpretation of satellite data. This article reviews estuarine and coastal remote sensing applications which require the high spatial and temporal resolutions provided by airborne sensors.
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One of the greatest challenges of coastal land-use policy is predicting future rates of sea-level rise from different proposed climate change scenarios. This study uses evidence from past higher Holocene and Pleistocene shorelines in southern Australia to develop possible response functions for future sea level modelling. A rule-of-thumb is determined by comparing rising sea levels of the past from relic intertidal biological markers with Antarctic temperature fluctuations during the mid-Holocene. The result is that for every 1°C increase in Southern Hemisphere relative temperatures, there would be, on average, a 0.9-m positive response in mean relative sea levels. Spectral analysis, comparing mean sea-level records from Sydney, Australia; the Southern Hemisphere temperature anomaly data (1850 to 2011); and Antarctic temperature fluctuations from the last 7000 years suggest that there are significantly longer (∼20 y and ∼50 y) periodicities that must be accounted for in any accurate determination of projections for 2100. For southern Australia, past sea-level rise appears to be in phase with Antarctic temperature changes and possible meltwater surges, suggesting that the use of linear sea-level rates per year, whilst convenient for planning, may be physically misleading. The policy response from the past should be a precautionary principle, based on centennial envelopes, capturing possible intermittent rapid surges that can be punctuated by decadinal stillstands. Three past—present—future (PPF) sea-level scenarios are applied to a case study of an area surrounding the Hexham Swamp, Newcastle, Australia. An impact infrastructure audit is undertaken, using a light detection and ranging geographic information system relative to multiple PPF centennial sea-level rise envelopes, to plan in this context for future sea-level rise.
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Excavations in the Helike Delta on the Gulf of Corinth have brought to light architectural remains from the Early Bronze Age (EBA), Geometric, Classical, Hellenistic, Roman, and Byzantine periods. Borehole results suggest that a lagoon intermittently occupied much of the delta during the Holocene. We discovered a well-preserved EBA settlement about 1km inland from the present shore, buried under 3 to 5m of fine sediments containing marine, brackish, and freshwater microfossils. A Classical site 130m away, buried under 3m of similar sediments, may have been destroyed by the earthquake and tsunami of 373 B.C., which submerged the city of Helike. Possible tsunami evidence is noted. Although the EBA and Classical sites were both long submerged and buried by lagoonal sediments, tectonic uplift has raised both horizons above sea level. A shallow black clay layer suggests that a marsh covered the Classical and EBA sites in Byzantine times. © 2011 Wiley Periodicals, Inc.
The Shuttle Radar Topography Mission (SRTM), that flew in February 2000, is a cooperative project between NASA and the National Imagery and Mapping Agency. SRTM employed a single-pass radar interferometer to produce a digital elevation model of the Earth's land surface between about 60 degrees norht and south latitude. Data processing will take about two years, although preliminary products are already available.
In this worldwide survey, Clive Gamble explores the evolution of the human imagination, without which we would not have become a global species. He sets out to determine the cognitive and social basis for our imaginative capacity and traces the evidence back into deep human history. He argues that it was the imaginative ability to "go beyond" and to create societies where people lived apart yet stayed in touch that made us such effective world settlers. To make his case Gamble brings together information from a wide range of disciplines: psychology, cognitive science, archaeology, palaeoanthropology, archaeogenetics, geography, quaternary science and anthropology. He presents a novel deep history that combines the archaeological evidence for fossil hominins with the selective forces of Pleistocene climate change, engages with the archaeogeneticists' models for population dispersal and displacement, and ends with the Europeans' rediscovery of the deep history settlement of the earth.