ArticlePDF Available

Late Holocene soil processes and the first evidence for ferruginous rhizoconcretions in cool subpolar environments of the Faroe Islands


Abstract and Figures

The Faroe Islands are characterized by high rates of Holocene geomorphological activity and demonstrable vegetation change, including substantial peat formation. Pedogenesis, especially in the late Holocene, is less well known. Numerous ferruginous rhizoconcretions consisting predominantly of Fe-oxyhydroxides were identified in loam and silty sands in Søltuvík on the island of Sandoy, dated prior to AD 1000. Their formation is related to intensive podzolization and they take the form of the source woody vegetation. The sub-fossil material represents the first evidence for ferruginous rhizoconcretions in the Faroese archipelago.
Content may be subject to copyright.
Full Terms & Conditions of access and use can be found at
Geografiska Annaler: Series A, Physical Geography
ISSN: 0435-3676 (Print) 1468-0459 (Online) Journal homepage:
Late Holocene soil processes and the first
evidence for ferruginous rhizoconcretions in cool
subpolar environments of the Faroe Islands
Richard Pokorný, Kevin J. Edwards, Lukáš Krmíček, Dalibor Všianský & Petra
Veronesi Dáňová
To cite this article: Richard Pokorný, Kevin J. Edwards, Lukáš Krmíček, Dalibor Všianský &
Petra Veronesi Dáňová (2018) Late Holocene soil processes and the first evidence for ferruginous
rhizoconcretions in cool subpolar environments of the Faroe Islands, Geografiska Annaler: Series
A, Physical Geography, 100:3, 272-284, DOI: 10.1080/04353676.2018.1463142
To link to this article:
Published online: 18 Apr 2018.
Submit your article to this journal
Article views: 34
View Crossmark data
Late Holocene soil processes and the first evidence for ferruginous
rhizoconcretions in cool subpolar environments of the Faroe
Richard Pokorný
, Kevin J. Edwards
, LukášKrmíček
, Dalibor Všianský
Petra Veronesi Dáňová
Faculty of Environment, Jan Evangelista PurkyněUniversity, Ústí nad Labem, Czech Republic;
Department of
Geological Sciences, Faculty of Science, Masaryk University, Brno, Czech Republic;
Department of Geography and
Environment, School of Geosciences, University of Aberdeen, Aberdeen, UK;
Clare Hall, University of Cambridge,
Cambridge, UK;
Faculty of Civil Engineering, AdMaS Centre, Brno University of Technology, Brno, Czech Republic;
Institute of Geology of the Czech Academy of Sciences, Prague, Czech Republic
The Faroe Islands are characterized by high rates of Holocene
geomorphological activity and demonstrable vegetation change,
including substantial peat formation. Pedogenesis, especially in the late
Holocene, is less well known. Numerous ferruginous rhizoconcretions
consisting predominantly of Fe-oxyhydroxides were identified in loam
and silty sands in Søltuvík on the island of Sandoy, dated prior to AD
1000. Their formation is related to intensive podzolization and they take
the form of the source woody vegetation. The sub-fossil material
represents the first evidence for ferruginous rhizoconcretions in the
Faroese archipelago.
Received 1 May 2017
Revised 17 January 2018
Accepted 31 January 2018
Faroe Islands; Holocene;
pedogenesis; peat; Fe-
.Pedogenic processes in Faroese soils of the mid to later Holocene are described.
.The development of a woody plant cover is demonstrated.
.The first occurrence of ferruginous rhizoconcretions in the Faroese archipelago is proven.
1. Introduction
The Faroe Islands (61°20N62°24N and 6°15W7°41W; Figure 1A) are located in the North
Atlantic Ocean. The archipelago consists of 18 major islands and covers an area of around
1400 km
. The territory was formed by massive basalt lava flows of Palaeocene age, interbedded
with sedimentary layers of continental origin (Storey et al. 2007). The Faroes have an extremely ocea-
nic climate, with mean July/August temperatures of 11°C and mean February temperatures of 4°C;
precipitation is concentrated in winter and is around 1400 mm y
close to sea level at the capital,
Tórshavn (Jóhansen 1985). The soil cover is strongly influenced by Holocene pedogenesis, with soil
types of moderate to high organic content, including peats and peaty soils (Rutherford and Taylor
1981,1982; Jóhansen 1989; Lawson et al. 2007).
© 2018 Swedish Society for Anthropology and Geography
CONTACT Richard Pokorný Faculty of Environment, Jan Evangelista PurkyněUniversity, Králova
šina 3132/7, Ústí nad Labem CZ-400 96, Czech Republic; Department of Geological Sciences, Faculty of Science, Masaryk Uni-
versity, Kotlářská 267/2, Brno CZ-611 37, Czech Republic
2018, VOL. 100, NO. 3, 272284
Faroese landscapes are characterized by an absence of trees, although prior to sustained human
settlement (c. 800 AD; Vickers et al. 2005; Olsen et al. 2010) low density wood and shrub commu-
nities were present (Hannon and Bradshaw 2000; Lawson et al. 2007,2008). Based on numerous
archaeological, palynological and entomological studies, mostly from the large islands of Streymoy,
Eysturoy, Sandoy and Suðuroy, landscape development since the Younger Dryas deglaciation (after
Figure 1. (A) Detailed aerial map of the bay at Søltuvík. The locality of rhizoconcretions is indicated by ®. (B) The Faroe Islands
archipelago. (C) The position of Faroe Islands in northern Europe (Map layers:, Umhvørvisstovan, Jarðfeingi).
10 300 cal yr BP, Olsen et al. 2010) is reasonably well known (Buckland and Dinnin 1998; Buckland
et al. 1998a,1998b; Edwards et al. 1998; Gathorne-Hardy et al. 2007).
During a detailed palaeontological survey (Pokorný et al. 2015), ferruginous concretions in Holo-
cene soil profiles were found at the bay of Søltuvík (61°5042.5′′ N, 6°5336.1′′ W) on the southwest
coast of Sandoy (Figure 1B). Ferruginous concretions are known in palaeosols from many locations
(Bown 1982; Gregory et al. 2004; Kraus and Hasiotis 2006; Genise et al. 2011) and they have been
shown previously in Palaeocene deposits from Streymoy (Ellis et al. 2002). These cited instances,
however, relate to formation under warm palaeoclimatic conditions. In cool subpolar temperature
conditions, the formation of concretions mineralized by Fe-oxyhydroxides is somewhat rarer. Alho-
nen et al. (1975) mentioned their occurrence in recent soils in central and northern Finland. For Ice-
land and the Faroe Islands, such phenomena seem not to have been described (Ólafur Arnalds,
Robert J. Blakemore and Paul C. Buckland, pers. comm.). This paper presents an explanation for
the origin of the concretions within the context of ecosystem change during the Holocene.
1.1. Quaternary sedimentological and pedological contexts
The Quaternary sediments of the Faroe Islands are mostly represented by unconsolidated and weakly
consolidated glacial drift deposits associated with Weichselian glacial clays, tillites, blockfields and
aeolian sands (Rasmussen 1972; Christiansen 1998; Humlum 1998; Humlum and Christiansen
Holocene pedogenesis followed deglaciation (Lawson et al. 2005,2007), with soil formation
strongly influenced by cool and humid subpolar oceanic climatic conditions, as well as the variation
caused by differences in altitude and slope position. Rutherford and Taylor (1981,1982) described
five main soil types that are mentioned here using IUSS Working Group WRB (2015) terminology:
regosols,cambisols (brunisols), histosols,podzols and gleysols (Table 1). It is important to note that not
all Faroese soil profiles are easily classifiable and some may feature combinations of features (cf.
Edwards et al. 2005a).
2. Material and methods
2.1. Spatial settings of the study area
The coastal fringe of Sandoy is relatively flat when compared to the high cliffs which characterize
coastal areas in many of the islands in the archipelago. A slight littoral inclination of slopes towards
the sea is apparent around Søltuvík. Quaternary sediments in which soil profiles have developed are
exposed in the eroded sides of the gully which leads into the bay (Figures 1B and 4A).
Table 1. Soil types and their occurrence in the Faroe Islands (Rutherford and Taylor 1981,1982).
Soil type Texture
altitude Conditions
Regosols Gravelly sandy loam Up to
60 cm
>300 m
Associated with glacial sediments, blockfields and
aeolian deposits; usually in areas devoid of
vegetation following the removal of peat and
overgrazing by sheep
Sandy clay loams Up to
50 cm
0400 m
In well to moderately drained areas
Histosols High organic content, often
visually homogeneous
Up to
200 cm
0700 m
In areas with heterogeneous ground moraine and
till-covered slopes adjacent to cirque floors and
U-shaped valleys
Podzols Sandy to silty loams with a
variable iron pan and a
mottled mineral layer
Up to
65 cm
<100 m
On gentle slopes with till and colluvial substrates
Gleysols Sandy loams with highly organic
surface horizons
Up to
70 cm
<400 m
In valleys with high water tables
At the sampled section (Figures 2 and 4B), the uppermost 10 cm of root-penetrated, grey peaty
topsoil overlies a light grey, sandy-gravel loam of 30 cm thickness. Within this stratum, at 2530 cm
below the surface, a distinctive zone of high Fe-oxyhydroxides is visible. An isolated piece of wood
(21 × 4 cm), identified to Larix sp. (larch, non-native), is inferred to be driftwood and was found at
the interface between the loam and the Fe-rich zone, 25 cm below the surface (Figure 3). Its radio-
carbon age is discussed below.
The sandy-gravel loam rests upon a 15-cm-thick layer of well-laminated, rusty-yellow silty sand,
probably of fluvial origin, featuring four thin (0.30.5 cm) yellow-grey layers with higher organic
Figure 2. The stratigraphic profile of the Quaternary sediment and soil on Søltuvík with the results of pH and TOC analysis.
Figure 3. The wood fragment (Larix sp.) found above the layer with the rhizoconcretions. The scale bar is 5 cm.
matter content, which may be colluvial in origin. Beneath the sand layer is a black peat of 5560 cm
thickness, containing rootlets, and which dries to a hard, brittle consistency. At 1.1 m, the peat rests
upon a thin (0.5 cm) iron pan and a basal layer of glacial diamictite. The latter is partially consoli-
dated grey tillite with weakly visible stratification. Its matrix is clayey, contains angular gravel and
cobbles. The section was excavated to a depth of 3.5 m.
Pedologically (see pH and TOC data on Figure 2), the observed soil profile as a whole is close to a
histosol (sensu IUSS Working Group WRB [2015]), although the upper part of the sequence (00.55
m) can be likened to a cambisol. Podzolization is also in evidence.
2.2. Field and laboratory methods
Sediment samples of 500 g weight were taken from all described layers of the profile together with
the collection of c. 20 ferruginous concretions.
For the pH and TOC analyses of the sedimentary layers, the samples were dried and sieved
through a mesh of 2 mm. A 5-ml dry sample was taken for pH analysis, mixed with 25 ml of KCl
solution and shaken for 60 min. After settling, the pH of the suspension was measured by a com-
bined electrode probe. TOC was measured on a PRIMACS Skalar autoanalyser and calculated as
the difference of total carbon (TC) obtained by burning at 1050°C in the presence of a catalyst
and inorganic carbon (IC) following reaction with 20% phosphoric acid at 105°C.
Phase and petrographic analyses of concretions were achieved by powder X-ray diffraction
(PXRD) and polarizing light microscopy. For the PXRD measurements, the sample was pulverized
and mixed with 10% fluorite (CaF
) used as an internal standard for the quantification of amorphous
phase content. The PXRD scan was acquired using a Panalytical Epmyrean diffractometer equipped
with a copper tube (λ
= 0.15418 nm) powered at 40 kV and 30 mA, and a Ni filter with Bragg
Brentano reflection geometry. Step size was 0.013 °2θ, time per step was 158 s, the angular range
580 °2θand the total duration of the scan was 5769 s. The data were processed using Panalytical
High Score 3 Plus software. The quantitative phase analysis was accomplished with the Rietveld
C radiocarbon dating of the fragment of Larix sp. was performed in the PoznańRadiocarbon
Laboratory (Lab. No. Poz-88954). Its age is discussed below. Dendrochronological correction was
implemented with the CALIB REV7.1.0 Radiocarbon Calibration Program and the IntCal13 cali-
bration curve (Stuiver and Reimer, 1993, Reimer et al., 2013).
Light microphotography was performed on thin sections using an Olympus BX 51 microscope.
3. Results
In the interval between the top of the Fe-rich zone to the laminated silty sands (0.250.55 m), fer-
ruginous concretions are frequent. They are vertical to subvertical, straight to slightly curved,
unbranched, 39 mm in diameter and up to 50 mm in length (Figure 4CG). In all samples, a central
cylindrical hollow is developed, within which thin, hair-like root remnants are sporadically pre-
served. The lower end of the concretions is blunt and cone shaped. The infill of the tubular cylinders
is structureless-sand grains in a rusty-brown Fe-oxyhydroxides matrix. The walls of the central hol-
low may display root epidermis of a darker colour or only its imprint. The rhizoconcretions always
feature a well-developed upper termination and there is no visible continuation into overlying layers.
The PXRD data are summarized in Table 2. They show that the crystalline part of the ferruginous
concretions predominantly consists of anorthite and clinopyroxene, and there is a probable presence
of low amounts of haematite and quartz. About 30%
of the sample is amorphous. The amor-
phous phase is probably formed by Fe-oxyhydroxides undetectable by PXRD due to low crystallinity.
The polished section of a rhizoconcretion sample was analysed with Raman spectroscopy to identify
the X-ray amorphous phase composition. However, no crystalline minerals except for anorthite and
clinopyroxene were identified.
The light microphotography confirmed that the concretions consisted of partly isotropic matrix
surrounding fragments of minerals and rocks. The observed mineral composition of the sample cor-
responds to the PXRD results. The rock species are represented by basaltic rocks and less abundant
andesites. Images of a rhizoconcretion are shown in Figure 5.
Figure 4. (A) The locality of the study site at Søltuvik. (B) The soil profile from basal peats to recent topsoil. (CG) Ferruginous
rhizoconcretions in the Fe-rich zone (C), sandy-gravel loam (D) and silty sands (EG). The scale bar on CGis1cm.
C radiocarbon age estimate for the fragment of Larix sp. found in the layer above the occur-
rence of ferruginous concretions was 940 ± 30 BP (cal. AD 10251160 [2σ]).
4. Discussion
4.1. Pedogenesis at Søltuvík
The glacial diamictites are probably of Weichselian age (Humlum 1998). Although the excavated
thickness at the study profile is 3.5 m (1.104.60 m), such sequences can reach 5 m in depth
depending on terrain and the disposition of the basal volcanic rocks.
Figure 5. Microphotographs of a rhizoconcretion sample. (A) Cross section of the whole sample (left: PPL, right: XPL, B = basaltic
rock, A = andesite, P = plagioclase/anorthite), (B) a fragment of a basaltic rock (XPL), (C) andesite fragment (XPL). Scale bar of A, B =
3 mm, C = 0.5 mm, D = 0.1 mm.
Table 2. The results of PXRD quantitative phase analysis.
Mineral %
Na-anorthite 50.9
Clinopyroxene (augite) 18.3
Quartz? 0.3
Haematite? 0.3
Amorphous phase (=Fe-oxyhydroxide) 30.2
In the early Holocene, the shallow, highly skeletal soils were relatively inorganic (Lawson et al.
2005,2007). They were not recognized at the study site where the soil profile starts with the peat
blanket (0.551.10 m); blanket peat, however, is a disputed term in Faroese mire terminology
(Edwards and Fosaa 2017). Lawson et al. (2007) concluded that peat formation in the Faroe Islands
had begun by 9000 cal. yr BP, with a possible concentration of initiation dates between c. 6000 and
4000 cal. yr BP. For the Lítlavatn area of Sandoy, an age range of 64506290 to 12901080 cal. yr BP
(2σ) was obtained (Lawson et al. 2007,2008). Given the depth of material at Søltuvík, an initiation
date at the earlier end of this spectrum might be expected.
The process of peat formation began with gradual paludification, weathering and plant cover
development. Lawson et al. (2007) considered that local topographic, hydrological and pedological
variations related to pedogenesis were more important than climate for the enactment of this process
in the Faroe Islands. Vegetation changed from fell-field communities to grasslands, tall herbs, dwarf
shrub blanket mire communities and sporadic trees or woods (Lawson et al. 2008). Although human
environmental impact over the last millennium is evident (Jóhansen 1985; McGovern et al. 1988;
Hannon and Bradshaw, 2000, Edwards et al. 2005b), ecosystems have been affected to a relatively
small degree and then mostly close to places of settlement. Human influence in encouraging the
spread of peat in the archipelago cannot be shown (Lawson et al. 2008); indeed, people have had
a negative effect upon peat development (Lawson et al. 2005, Vickers et al. 2005, Church et al. 2013).
Significant landscape development is reflected in the upper 55 cm of the Søltuvík soil profile. The
sandy-gravel loams and silty sands have analogues on Sandoy (Lawson et al. 2005) and Suðuroy
(Edwards et al. 2005a; Mairs 2007). These horizons have origins in soil development within colluvial
deposits. Edwards et al. (2005a) and Lawson et al. (2005) inferred that the last c. 3000 years were less
geomorphologically stable than the middle Holocene: lower slopes were destabilized, the extensive
lowland peat cover was disrupted and this resulted in a more varied landscape mosaic. Precise
reasons for slope-based mass movements are difficult to determine, but continuing landscape degra-
dation may have been accentuated by climatic changes or even by changing patterns in the large
colonies of nesting birds (Lawson et al. 2005). The formation of the surface capping of peaty topsoil
(00.10 m) may be explained by changes in local slope processes whereby there has been less ener-
getic remobilization of transported material.
4.2. Origin of the ferruginous concretions and the relevant soil processes
The occurrence of the ferruginous concretions at Søltuvík is limited to the profile section having an
increased content of Fe-oxyhydroxides (0.250.55 m). To explain this, it is necessary to enlist pro-
cesses associated with the origin of the ferrous materials. In the period following the major period of
peat formation, pedogenesis within the mineral soil segment of the profile would have begun. Eroded
fragments of basaltic rocks, transported from up-slope and up-valley areas, started to weather
mechanically and chemically. Fe-oxyhydroxides in the weathered basalt migrated downward
through the soil profile due to complex processes in which podzolization probably had a dominant
role (Alhonen et al. 1975, Ellis 1988, Mendelssohn et al. 1995, Veihe and Thers 2007). The intensive
leaching of Fe cations is accentuated by low base saturation and the low pH of the upper soil profiles
(Rutherford and Taylor 1981,1982).
The ferruginous concretions at Søltuvík can be explained as the pedodiagenetic mineral accumu-
lations around the plant roots, i.e. rhizoconcretions sensu stricto (Klappa 1980). Due to the absence
of specific morphological features, it is not possible to decide whether they were formed around liv-
ing or dead roots, but both possibilities might be assumed. Root growth can change the physico-
chemical conditions of the surrounding soil, producing cementation and precipitation of Fe-
oxyhydroxides in the rhizosphere through the release of polysaccharides, organic acids, electrons
and protons, packing of soil, evapotranspiration and the association with microorganisms (Violante
et al. 2003). The vertical transport of dissolved Fe-oxyhydroxides may have been accelerated by the
deep rhizosphere, with decayed root channels forming a conduit for the percolate, together with
enhanced oxygenation. Ferruginous precipitate seems likely to have been deposited inside the chan-
nels (Kraus and Hasiotis 2006). As suggested by the slope of the diamictite and basaltic basement and
the direction of groundwater flow, the soil at Søltuvík was likely significantly moist during the
growth of the rhizoconcretions, but not saturated.
Although the occurrence of ferruginous rhizoconcretions at Søltuvík is probably explained by
podzolization as the main formation process, the local climatic and hydrological conditions suggest
that the creation of Fe (or Mn, Al) rhizoconcretions may also be associated with the anoxic soil con-
ditions in wetlands or lake fringes (cf. Mendelssohn et al. 1995). The aforementioned authors review
the biotic and abiotic processes leading to the formation of oxidized root channels and iron plaques.
As main controlling factors, they designated especially the availability of soil iron and the oxidizing
capacity of plant roots.
In his study of forest floors in British Columbia, Canada, Quesnel (1980) noted the propensity of
plants to accumulate and precipitate Fe and Al ions in the rhizosphere following preferential uptake
from physicochemical processes; the subsequent decomposition of fine roots would increase the con-
centration of Fe in the adjacent forest floor as rhizoconcretions. Alhonen et al. (1975) discussed the
formation of the concentric ring-like structure of FeMn rhizoconcretions found in Finland and sta-
ted that the distribution of Fe and Mn is caused due to alternating oxidation and reduction, i.e. dry
and wet climatic cycles.
4.3. Tracemakers
Any distinctive channels aiding fluid flows in the soil profile would also assist burrowing by earth-
worms or dung beetles. However, the notion of animal origins must be rejected for the following
reasons. Earthworm traces are characterized by meniscate infill, the annulation of wall linings and
the presence of faecal pellets or aestivation chambers (Canti 2003; Verde et al. 2007; Smith et al.
2008a); structures made by dung beetles have vertical menisci, and claw marks on the inner wall
of burrows or nesting chambers are present (Retallack 1984; Genise et al. 2000; Smith et al.
2008b). These diagnostic features are missing in the observed ferruginous concretions. Moreover,
the Faroe Islands has only one species of dung beetle (Aphodius lapponum) and about 10 species
of earthworms (Lombricus terrestris and Apporectodea rosea could be envisaged due to their ethol-
ogy), and all of them are assumed to occur only since the period of settlement (Enckell and Rundgren
1983,1988; Buckland and Dinnin 1998; Buckland and Panagiotakopulu 2005). The age of the con-
cretions is estimated to pre-date human colonization.
A plant origin for the concretions would conform to the central hollow and the frequent remains
or imprints of roots on the cylinder walls. The question remains as to the exact plant species respon-
sible. At present, herbaceous vegetation with a dominance of grasses and sedges occurs over exten-
sive areas around Søltuvík. The average diameter of the rhizoconcretions reaches 5 mm, which is
markedly larger than the roots of such herb types.
There is a high probability that the root channels are the remnants of woody plants. The presence
of dwarf shrubs (mainly Calluna vulgaris), shrubs (Salix ssp., Juniperus communis) and scattered
trees (Betula pubescens) is well confirmed palaeobotanically in the Faroe Islands through the greater
part of the Holocene (Edwards et al. 2005a; Hannon et al. 2005; Lawson et al. 2005,2008; Andresen
et al. 2006; Edwards 2008).
Although the
C radiocarbon age for the aforementioned wood fragment was determined (cal.
AD 10251160), it cannot provide a certain date for the deposit in which it was located because it
is likely to be driftwood. Even if it was several decades old when emplaced, it would indicate that
the underlying rhizoconcretions pre-date AD 1000. This is also supported by the fact that the rhi-
zoconcretions, including the inner hair-like root remnants, have no visible continuation into the
overlying layers. The same effect, but without the rhizoconcretions, can also be observed in the over-
lying sandy-gravel loams at depths of 0.10.25 m, above the zone of limonitization. It can be
explained by the growth of source plants during the formation and emplacement of the adjacent
strata. Loosely speaking, this would not be inconsistent with the
C dating of soil, peat and lacus-
trine sediments at other sites on Sandoy (cf. Lawson et al. 2007,2008) and elsewhere in the Faroe
Islands, which span much of the Holocene. We would assume the Søltuvík rhizoconcretions were
formed in the mid to latter half of this period given their stratigraphic position in the profile.
5. Conclusion
The numerous ferruginous rhizoconcretions found in sandy-gravel loam and silty sands at Søltuvík
represent specific sedimentological conditions on the Faroe Islands at a date assumed to be in the
mid to later Holocene and likely prior to AD 1000. Crucial to rhizoconcretion formation was the
combination of pedogenic processes (podzolization) and a plant cover containing scattered shrubs
and trees. The sub-fossil material described here represents the first evidence for ferruginous rhizo-
concretions in the cool subpolar oceanic climate of the Faroe Islands.
The authors would like to thank Uni E. Árting (University of the Faroe Islands, Tórshavn, Faroe Islands) for admin-
istrative assistance connected with the research in the Faroe Islands; Ólafur Arnalds and Bjarni D. Sigurðsson (The
Agricultural University of Iceland) for comparative discussion on Icelandic and Faroese soils; Paul C. Buckland (Shef-
field, UK) and Robert J. Blakemore (Hanyang University, Seoul, Korea) for advice about possible tracemakers and
landscape conditions in northern Europe; V. Koutecký (Charles University in Prague, Czech Republic) for the
wood identification and LukášKraft for help with fieldwork. Thanks also belong to the PoznańRadiocarbon Labora-
tory (Poland) and especially to Thomas Goszlar for the
C dating and to M. Maříková (Czech Academy of Sciences,
Prague) and M. Došek (J. E. PurkyněUniversity in Ústí nad Labem) for chemical analysis.
Disclosure statement
No potential conflict of interest was reported by the authors.
This work was supported by Project of Severočeské doly a.s. [Grant Number SD-30/09/16-1]; J. E. PurkyněUniversity
Internal Grant Agency [Grant Number FŽP UJEP IG 1/2014].
Notes on contributors
Richard Pokorný is an Assistant Professor at the Jan Evangelista PurkyněUniversity, Faculty of the Environment, Ústí
nad Labem, Czech Republic. He is interested especially in ichnopaleontology in the region of Arctic and Subarctic. At
this moment, he also works on the monograph aimed at the history of coal mining in Iceland.
Kevin J. Edwards is Emeritus Professor in Physical Geography at the University of Aberdeen, United Kingdom. He has
particular interests in environmental change in the North Atlantic region and the palaeoecological basis of human
environment interactions.
LukášKrmíček is an Associate Professor at the Brno University of Technology, Faculty of Civil Engineering, Brno,
Czech Republic. He is interested in geological processes in polar and sub-polar regions.
Dalibor Všianský is an Assistant Professor at the Masaryk University, Faculty of Science, Department of Geological
Sciences, Brno, Czech Republic. He focuses on mineralogy of silicate industrial materials and X-ray diffraction and
microscopic techniques.
Petra Veronesi Dáňová is a lab technician at the Jan Evangelista PurkyněUniversity, Faculty of the Environment, Ústí
nad Labem, Czech Republic.
Richard Pokorný
Kevin J. Edwards
Dalibor Všianský
Alhonen P, Koljonen T, Lahermo P, Uusinoka R. 1975. Ferruginous concretions around root channels in clay and fine
sand deposits. Bull Geol Soc Finl. 47:175181. doi:10.17741/bgsf/47.1-2.020.
Andresen CS, Björck S, Rundgren M, Conley DJ, Jessen C. 2006. Rapid Holocene climate changes in the North
Atlantic: evidence from lake sediments from the Faroe Islands. Boreas. 35:2334. doi:10.1080/03009480500359228.
Bown TM. 1982. Ichnofossils and rhizoliths of the nearshore fluvial Jebel Qatrani Formation (Oligocene), Fayum
Province, Egypt. Palaeogeogr Palaeoclimatol Palaeoecol. 40(4):255309. doi:10.1016/0031-0182(82)90031-1.
Buckland PC, Dinnin MH. 1998. Insect faunas at landnám: a palaeoentomological study at Tjørnuvík, Streymoy, Faroe
Islands. Fróðskaparrit. 46:277286.
Buckland PC, Edwards KJ, Sadler JP. 1998a. Early Holocene investigations at Saksunardalur and the origins of the
Faroese biota. Fróðskaparrit. 46:259266.
Buckland PC, Edwards KJ, Sadler JP, Dinnin MH. 1998b. Late Holocene insect faunas from Mykines, Faroe Islands,
with observations on associated pollen and early settlement records. Fróðskaparrit. 46:287296.
Buckland PC, Panagiotakopulu E. 2005. Archaeology and the Palaeoecology of the Norse Atlantic Islands: a Review. In:
Mortensen A, Arge SV, editors. Viking and Norse in the North Atlantic, Select Papers from the Proceedings of the 14th
Viking Congress,Tórshavn; July 1930, 2001. AnnalesSocietatis ScientiarumFaeroensis Supplementum, 44, p. 136150.
Canti MG. 2003. Earthworm activity and archaeological stratigraphy: a review of products and processes. J Archaeol
Sci. 30:135148. doi:10.1006/jasc.2001.0770.
Church MJ, Arge SV, Edwards KJ, Ascough PL, Bond JM, Cook GT, Dockrill SJ, Dugmore AJ, McGovern TH, Nesbitt
C, Simpson IA. 2013. The Vikings were not the first colonizers of the Faroe Islands. Quat Sci Rev. 77:228232.
Christiansen HH. 1998. Highland aeolian deposits in the Faroe Islands. Fróðskaparrit. 46:205213.
Edwards KJ. 2008. Juniper, goats and the Norse: did the decline of Juniperus in the Faroe Islands have a human cause?
In: Paulsen C., Michelsen H.D., editor. Símunarbók. Heiðursrit til Símun V. Arge á 60 ára degnum. Tórshavn:
Fróðskapur, Faroe University Press; p. 5871.
Edwards KJ, Borthwick D, Cook G, Dugmore AJ, Mairs K-A, Church MJ, Simpson IA, Adderley WP. 2005a. A hypoth-
esis-based approach to landscape change in Suðuroy, Faroe Islands. In: Edwards KJ, editor. Historical Human
Ecology of the Faroe Islands. Hum Ecol. 33(5):621650. doi:10.1007/s10745-005-4746-0.
Edwards KJ, Buckland PC, Craigie R, Panagiotakopulu E, Stummann Hansen S. 1998. Landscapes at landnám: paly-
nological and palaeoentomological evidence from Toftanes, Faroe Islands. Fróðskaparrit. 46:229244.
Edwards KJ, Fosaa AM. 2017. Faroe Islands. In: Joosten H, Tanneberger F, Moen A, editor. Mires and peatlands of
Europe. Status, distribution and conservation. Stuttgart: Schweizerbart Science Publishers; p. 372375. doi:10.
Edwards KJ, Lawson IT, Erlendsson E, Dugmore AJ. 2005b. Landscapes of contrast in Viking age Iceland and the Faroe
Islands. Landscapes. 6(2):6381. doi:10.1179/lan.2005.6.2.63.
Ellis D, Bell BR, Jolley DW, OCallaghan M. 2002. The stratigraphy, environment of eruption and age of the Faroes
Lava Group, NE Atlantic Ocean. In: Jolley DW, Bell BR, editors. The North Atlantic igneous province: stratigraphy,
tectonic, volcanic and magmatic processes. Geological Society of London, Special Publication, 197:253269. doi:10.
Ellis S. 1988. Pedogenesis on the basalt and associated deposits of Canna, western Scotland. Catena. 15:281287. doi:10.
Enckell PH, Rundgren S. 1983. Terrestrial invertebrates of the Faroe Islands: V. Earthworms (Lumbricidae): distri-
bution and habitats. Fauna Norvegica A. 4:1120.
Enckell PH, Rundgren S. 1988. Anthropochorous earthworms (Lumbricidae) as indicators of abandoned settlements
in the Faroe Islands. J Archaeol Sci. 15:439451. doi:10.1016/0305-4403(88)90041-6.
Gathorne-Hardy FJ, Lawson IT, Church MJ, Brooks SJ, Buckland PC, Edwards KJ. 2007. The Chironomidae of
Gróthúsvatn, Sandoy, Faroe Islands: climatic and lake-phosphorus reconstructions, and the impact of human settle-
ment. Holocene. 17:12591264. doi:10.1177/0959683607085133.
Genise JG, Bellosi ES, Verde M, González MG. 2011. Large ferruginized palaeorhizospheres from a Paleogene lateritic
profile of Uruguay. Sediment Geol. 240:8596. doi:10.1016/j.sedgeo.2011.08.008.
Genise JF, Mángano MG, Buatois LA, Laza JH, Verde M. 2000. Insect trace fossil associations in Paleosols: the
Coprinisphaera Ichnofacies. Palaios. 15:4964. doi:10.1669/0883-1351(2000)015< 0049:ITFAIP>2.0.CO;2.
Gregory MR, Martin AJ, Campbell KA. 2004. Compound trace fossils formed by plant and animal interactions:
Quaternary of northern New Zealand and Sapelo Island, Georgia (USA). Fossils Strata. 51:88105.
Hannon GE, Bradshaw RHW. 2000. Impacts and timing of the first human settlement on vegetation of the Faroe
Islands. Quat Res. 54:404413. doi:10.1006/qres.2000.2171.
Hannon GE, Bradshaw RHW, Bradshaw EG, Snowball I, Wastegård S, 2005. Climate change and human settlement as
drivers of Late Holocene vegetational change in the Faroe Islands. Holocene. 15:639647. doi:10.1191/
Humlum O. 1998. Rock glaciers on the Faeroe Islands, the North Atlantic. J Quater Sci. 13:293307. doi:10.1002/
(SICI)1099-1417(199807/08)13:4 &lt; 293::AID-JQS370 > 3.0.CO;2-S.
Humlum O, Christiansen HH. 1998. Mountain climate and periglacial phenomena in the Faeroe islands. Permafrost
Periglacial Process. 9:189211. doi:10.1002/(SICI)1099-1530(199807/09)9:3 &lt; 189::AID-PPP287 > 3.0.CO;2-N.
IUSS Working Group WRB. 2015. World reference base for soil resources 2014, update 2015. International soil classi-
fication system for naming soils and creating legends for soil maps. World Soil Resources Reports 106. FAO, Rome.
192 p.
Jóhansen J. 1985. Studies in the vegetational history of the Faroe and Shetland Islands. Ann Soc Sci Faeroensis Suppl.
Jóhansen J. 1989. Survey of geology, climate and vegetational history. In: Højgaard A, Jóhansen J, Ødum S, editors. A
Century of Tree-Planting in the Faroe Islands. Ann Soc Sci Færoensis Suppl. 14:1115.
Klappa CF. 1980. Rhizoliths in terrestrial carbonates: classification. recognition, genesis and significance.
Sedimentology. 27(6):613629. doi:10.1111/j.1365-3091.1980.tb01651.x.
Kraus MJ, Hasiotis ST. 2006. Significance of different modes of rhizolith preservation to interpreting paleoenviron-
mental and paleohydrologic settings: examples from Paleogene paleosols, Bighorn basin, Wyoming, U.S.A. J
Sediment Res. 76:633646. doi:10.2110/jsr.2006.052.
Lawson IT, Church MJ, McGovern TH, Arge SV, Woollet J, Edwards KJ, Gathorne-Hardy FJ, Dugmore AJ, Cook G,
Mairs K-A, et al. 2005. Historical ecology on Sandoy, Faroe Islands: palaeoenvironmental and archaeological per-
spectives. Hum Ecol. 33(5):651684. doi:10.1007/s10745-005-7681-1.
Lawson IT, Church MJ, Edwards KJ, Cook GT, Dugmore AJ. 2007. Peat initiation in the Faroe Islands: climate change,
pedogenesis or human impact? Earth Environ Sci Trans R Soc Edinburgh. 98:1528. doi:10.1017/
Lawson IT, Edwards KJ, Church MJ, Newton AJ, Cook GT, Gathorne-Hardy FJ, Dugmore AJ. 2008. Human impact on
an island ecosystem: pollen data from Sandoy, Faroe Islands. J Biogeogr. 35:11301152. doi:10.1111/j.1365-2699.
Mairs K-A. 2007. Islands and human impact: under what circumstances do people put unsustainable demands on
island environments? Evidence from the North Atlantic [PhD diss., School of Geosciences]. UK: University of
Edinburgh. 398 p.
McGovern TH, Bigelow G, Amorosi T, Russell D. 1988. Northern Islands, human error, and environmental degra-
dation: a view of social and ecological change in the medieval North Atlantic. Hum Ecol, 16. 3:225270. doi:10.
Mendelssohn IA, Kleiss BA, Wakeley JS. 1995. Factors controlling the formation of oxidized root channels: a review.
Wetlands. 15(1):3746. doi:10.1007/BF03160678.
Olsen J, Björck S, Leng MJ, Gudmundsdóttir ER, Odgaard BV, Lutz CM, Kendrick CP, Andersen TJ, Seidenkrantz M-
S. 2010. Lacustrine evidence of Holocene environmental change from three Faroese lakes: a multiproxy XRF and
stable isotope study. Quat Sci Rev. 29:27642780. doi:10.1016/j.quascirev.2010.06.029.
Pokorný R, Krmíček L, Árting UE. 2015. The first evidence of trace fossils and pseudo-fossils in the continental inter-
lava volcaniclastic sediments on the Faroe Islands. Bull Geol Soc Den. 63:4557.
Quesnel HJ. 1980. Forest floors near port hardy, British Columbia, Canada [Ph.D. diss]. Canada: The Faculty of gradu-
ate studies, The University of British Columbia .
Rasmussen J. 1972. Mórena á Borðoyarvík, súm bendir á eitt millumbil í glersetingini har norðuri. Fróðskaparrit.
Reimer PJ, Bard E, Bayliss A, Beck JW, Blackwell PG, Bronk Ramsey C, Buck CE, Cheng H, Edwards RL, Friedrich M,
et al. 2013. Intcal13 and Marine13 radiocarbon age calibration curves 050,000 years cal BP. Radiocarbon. 55:1869
1887. doi:10.2458/azu_js_rc.55.16947.
Retallack GJ. 1984. Trace fossils of burrowing beetles and bees in an Oligocene paleosol, Badlands National Park, South
Dakota. J Paleontol. 58(2):571592.
Rutherford GK, Taylor CEB. 1981. The soils of the Faeroe Islands. Geoderma. 25:231244. doi:10.1016/0016-7061
Rutherford GK, Taylor CEB. 1982. Soils of the Faroe Islands. In: Rutherford GK, editor. The Physical Environment of
the Faeroe Islands. Monogr Biol. 46:111124.
Smith JJ, Hasiotis ST, Kraus MJ, Woody DT. 2008a. Relationship of floodplain ichnocoenoses to paleopedology, paleo-
hydrology, and paleoclimate in the Willwood Formation, Bighorn Basin, Wyoming, during the PaleoceneEocene
thermal maximum. Palaios. 23:683699. doi:10.2110/palo.2007.p07-080r.
Smith JJ, Hasiotis ST, Kraus MJ, Woody DT. 2008b.Naktodemasis bowni: new ichnogenus and ichnospecies for
Adhesive Meniscate Burrows (AMB), and paleoenvironmental implications, Paleogene Willwood Formation,
Bighorn Basin, Wyoming. J Paleontol. 82(2):267278. doi:10.1666/06-023.1.
Storey M, Duncan RA, Tegner C. 2007. Timing and duration of volcanism in the North Atlantic Igneous Province:
implications for geodynamics and links to the Iceland hotspot. Chem Geol. 241:264281. doi:10.1016/j.chemgeo.
Stuiver M, Reimer PJ. 1993. Extended
C data base and revised CALIB 3.0
C age calibration program. Radiocarbon.
35:215230. doi:10.1017/S0033822200013904.
Vickers K, Bending J, Buckland PC, Edwards KJ, Stummann Hansen S, Cook G. 2005. Toftanes: The paleoecology of a
Faroese Landnám farm. In: Edwards KJ, editor. Historical human ecology of the Faroe Islands. Hum Ecol. 33
(5):685710. doi:10.1007/s10745-005-4744-2.
Veihe A, Thers M. 2007. Pedogenesis and root development in a complex geomorphologic setting of the Faroe Islands.
Commun Soil Sci Plant Anal. 38:293314. doi:10.1080/00103620601172266.
Verde M, Ubilla M, Jiménez JJ, Genise JF. 2007. A new earthworm trace fossil from paleosols: aestivation chambers
from the Late Pleistocene Sopas Formation of Uruguay. Palaeogeogr Palaeoclimatol Palaeoecol. 243:339347.
Violante A, Barberis E, Pigna M, Boero V. 2003. Factors affecting the formation, nature, and properties of iron pre-
cipitation products at the soilroot interface. J Plant Nutr. 26:18891908. doi:10.1081/PLN-120024252.
... In comparing with the current character of the landscape it can be assumed, that the traces illustrate the changing of landscape in possible relation with the landnám (=an Icelandic/Faroese term for the first settlement of Faroe Islands) and the beginning of pastoral farming. The sub-fossil material described here represents the first evidence for ferruginous rhizoconcretions in the cool subpolar oceanic climate of the Faroe Islands (Pokorný et al. 2018b). ...
... Higher than herbaceous vegetation is almost absent in the Faroe Islands today, and using radiocarbon analysis it can be assumed that rhizolites was formed shortly before the first human settlement of the Faroe Islands. It can indirectly testify to the anthropogenic impact on the landscape mosaic changes (Pokorný et al. 2018b). ...
... -general view of the study site at Søltuvík; B -stratigraphic profile of the Quaternary sediment and soil on Søltuvík with the results of pH and TOC analysis; C-D -ferruginous rhizoconcretions in the silty sands (the scale bar on C-G is 1 cm)(Pokorný et al. 2018b). ...
Iceland and Faroe Islands represent a classical example of an area fully formed by volcanic activity. Their geological history goes back to the Lower Palaeogene when the northern part of Mid-Atlantic Ridge was active in the area of hotspot expression. Thick effusions and sheet intrusions of tholeiitic plateau basalts of Palaeogene age are characteristic for the Faroe Islands. Undersea volcanism which continuously cropped up and extruded the surface began in the Middle Miocene. The sequence of volcano-stratigraphic units with numerous volcaniclastic sedimentary layers is typical for both regions. However, there is one significant difference – in Iceland the marine and coastal deposits dominate but in the Faroe Islands mostly freshwater sediments are concerned. Marine fauna is often preserved in the Icelandic sediments, for example Bivalvia, Gastropoda, Scaphopoda, Cirripedia, Annelida etc. In non-marine ecosystems, fossil plants, which locally form coal layers, dominate. Freshwater and terrestrial animals are much rarer. Fossil records of animal activities have not been studied there yet; however, their information potential has a great potential. Before the research presented in here, only three ichnologic papers were published and in several others the traces are only marginally mentioned. No animal fossils from the Palaeogene age have been discovered in the Faroe archipelago yet, the same goes for the trace fossils. The only knowledge relates to the fossil plants. From the period after the end of the volcanic activity the finds of fossils are mostly limited to the Holocene age, except the Eemian wood fragments from the unique locality on the Borðoy Island. In 2012–2018, a detailed paleontological research was carried out in the above mentioned European part of Arctic and Subarctic. Various bioerosion traces of Weichselian age were identified in the glaciomarine sediments, which remained after mechanic damages on shells of mollusc or barnacle, caused by the activity of predators; or after attachment of epibiotic organisms (e.g. Anellusichnus, Caulostrepsis, Centrichnus, Clionolithes, Finichnus and Oichnus), a lot of traces of locomotion were also found on the surface or inside sediment (will be published in the coming years). Resting traces and escape traces were also found here in the marine and also freshwater environments (Miocene). It is not surprising that the marine ichnoassemblages show the worldwide geographic range; on the other hand, the lacustrine trace fossils are mostly endemic (Helminthoidichnites, Mammillichnis, Thorichnus igen. nov. and Vatnaspor igen. nov.). In the Faroe Islands, the character of the Palaeogene landscape and ecosystems was quite well known based on the knowledge about the fossil plants and lithology of the volcaniclastic sediments. However, the proof of the animal presence was still missing. Although expected, the finding of Helminthoidichnites isp. and ?Palaeophycus isp. on the Eysturoy Island was important. Another but significantly younger trace fossils (Teredolites) were identified in the wood fragments comes from gyttja coastal cliffs of Eemian age. Terminal deposit place of driftwood in the lake basin connected with sea allows a big discussion about principal directions of sea currents in the last interglacial, despite their origin in high seas. The youngest confirmed traces come from the late Holocene soil profile. These are rhizoliths that testify the change of the landscape in the age of first human settlement of Faroe Islands. At present, the trace fossils mentioned above represent the first and only occurrence of trace fossils on the Faroe Islands.
Full-text available
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working ...
Full-text available
Spherically layered ferruginous concretions formed in soils in Finland are described. The cementing iron-rich material is in an amorphic state and binds the loose detrital mineral grains of quartz, feldspars, amphiboles, etc. Electron microprobe analyses show that iron and manganese are present as concentric rings around the root channels but that calcium is evenly distributed. The highest manganese content is found near the channel as a dark almost black layer or spot, but around the centre, where the content of cementing materials decreases, iron predominates. The origin of these ferruginous concretions and the significance of redox conditions in soils during their formation are discussed.
Full-text available
Interlava volcaniclastic sediments, mostly sandstones, from the Palaeogene Faroe Islands Basalt Group (Malinstindur and Sneis Formations) contain rare ichnofauna and well-preserved pseudo-fossils in the form of linear structures. Five specimens of two ichnogenera have been identified, which include Helminthoidichnites isp. and ?Palaeophycus isp. The linear structures are interpreted to be desiccation cracks. This association indicates an environment with low to moderate hydrodynamic energy, which confirms a mosaic landscape of floodplains with rivers and shallow lakes.
Full-text available
We report on the earliest archaeological evidence from the Faroe Islands, placing human colonization in the 4th-6th centuries AD, at least 300-500 years earlier than previously demonstrated archaeologically. The evidence consists of an extensive wind-blown sand deposit containing patches of burnt peat ash of anthropogenic origin. Samples of carbonised barley grains from two of these ash patches produced 14C dates of two pre-Viking phases within the 4th-6th and late 6th-8th centuries AD. A re-evaluation is required of the nature, scale and timing of the human colonization of the Faroes and the wider North Atlantic region.
The arrival of the Vikings in the Faroe Islands and Iceland in the ninth century AD from Scandinavian and British Isles homelands essentially represented the colonisation of virgin landscapes. Environmental investigations show that their imported agricultural package was supplemented in coastal areas by bird and marine resources which, for the Faroes at least, continued to be of significance. The Faroese also developed appropriate land management practices such as outfield grazing and soil augmentation to counteract any detrimental affects arising from, for instance, reductions in the bird population, soil and slope erosion and the lack of naturally fertile soils. It seems that there had always been sufficient resources available for an enterprising human population and that the Faroes did not exceed their carrying capacity during the Norse period. The Icelanders faced different challenges: a more extreme climate, the rapid and substantial erosion of volcanic soils following settlement and the disappearance of what had probably been a substantial woodland resource. Actions were taken to conserve woodlands before they were completely destroyed and regulatory mechanisms assisted the maintenance of grazing, but did not stem soil erosion.
A number of iron oxides (hematite, goethite, lepidocrocite, maghemite, and magnetite) or short‐range ordered precipitates (ferrihydrite) may be found in soil environments, but in the rhizosphere the presence of organic ligands released by plants (exudates) or microorganisms promote the formation of ferrihydrite. Iron ions are liberated into soil solution by acidic weathering of minerals and then precipitated either locally or after translocation in soil environments. Humic and fulvic acids as well as organic substances produced by plants and microorganisms are involved in the weathering of primary minerals. Organic compounds play a very important role in the hydrolytic reactions of iron and on the formation, nature, surface properties, reactivity, and transformation of Fe oxides. Organic substances present in the rhizosphere interact with Fe promoting the formation of ferrihydrite and organo‐mineral complexes. The solubility of Fe precipitation products is usually low. However, the formation of soluble complexes of Fe(II) or Fe(III) with organic ligands, usually present in the rhizosphere increases the solubility of Fe‐oxides. Mobilization of Fe from Fe oxides by siderophores is of great importance in natural systems. They can form stable Fe(III) complexes (pK up to 32) and thus mobilize Fe from Fe(III) compounds. These higher Fe concentrations are important for the supply of Fe to plant roots which excrete organic acids at the soil–root interface. Iron oxides adsorb a wide variety of organic and inorganic anions and cations, which include natural organics, nutrients, and xenobiotics. There is competition between anions and cations for the surfaces of Fe‐oxides. Root exudates suppress phosphate or sulfate adsorption on Fe‐oxides. This is a mechanism by which plant roots mobilize adsorbed phosphate and improve their phosphate supply. Anions adsorption on iron oxides modify their dispersion/flocculation behavior and thus their mobility in the soil system. That can increase or decrease the possibility of contact between Fe‐oxides and organics or organisms able to dissolve them.