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Journal ArticleDOI

Erosion of the Geodetic Hills Fossil Forest, Axel Heiberg Island, Northwest Territories

C. Bigras, M. Bilz, D.W. Grattan, C. Gruchy 
01 Jan 1995-Arctic-Vol. 48, Iss: 4, pp 342-353

AbstractStudies on the erosion of the Geodetic Hills Fossil Forest on the east side of Axel Heiberg Island, Northwest Territories have indicated that erosion by wind averaged a depth of 1.3 cm for the period 1988 to 1992. The fossil wood and leaf litter tend to dry on exposure, resulting in shrinkage and fragmentation - sometimes in less than a year. Frost, especially at the boundaries of polygons, repeatedly compresses and disrupts the fossil-bearing strata. Erosion by water takes place as rills on the sides of hills. Solifluction displaces surface sediment on the sides of the hills in the range of 6 to 45 cm per year. In the last few years the physical disruption of stumps, tree trunks and forest mat has been caused mainly by people: by walking on the site, by excavating it, and by flying over and landing helicopters on it. Natural processes - including wind, freezing and thawing, rainfall, and wandering animals - also cause damage. In 1992, 62 stumps recorded in the 1988 survey (ca. 10% of the total) could not be relocated. There are problems in accounting for this discrepancy, because only a few stumps are known to have been removed by investigators for study, and it seems unlikely (although it is possible) that others may have been removed by unknown visitors. Some of the "missing" stumps may still be present, but disturbance in the surface sediment caused by scientific excavation or wind-driven accretion have made them untraceable. Vestigial stumps may simply have weathered away in the period between surveys, and finally some of the losses may be accounted for by errors in the initial surveying. Since preservation is important both for long-term scientific interpretation and for public access, the site should be better managed. The authors advocate that the site be managed by the Canadian Parks Service as an annex to Ellesmere Island National Park Reserve. Key words: fossil forest, Axel Heiberg Island, wood, leaf litter, erosion, preservation

Topics: Fossil wood (55%), Solifluction (51%)

Summary (2 min read)

INTRODUCTION

  • The discovery in August 1985 of the fossil forest at Geodetic Hills on Axel Heiberg Island, 79˚55'N, 89˚02'W, (Fig. 1) sparked much academic and popular interest not only because of its large size, but also because of the remarkable nature of the fossils preserved there.
  • Fossil forests have been defined as “groups of preserved tree stumps found generally in growth Many of the initial specimens recovered for the museum— which included a tree stump, cones, and sections of leaf mat—were very fragile, and some tended to disintegrate after removal from their arctic environment to the laboratory.
  • For these reasons, the Canadian Conservation Institute, (CCI) was invited to become involved in the project.
  • For six years, the authors have studied the effect of the natural environment, as well as the impact of people.
  • This includes photography and mapping of stumps and logs, aerial photography, and monitoring of erosion markers placed in sensitive locations.

THE FOSSIL FOREST SITE

  • Many large tree stumps project from the ground, and several periods of forest growth are evident in forest litter containing strata interspersed with sands and silt deposits (Francis and McMillan, 1987; Francis, 1991; Ricketts, 1991).
  • The site is remarkable for the unusual condition of the specimens that are commonly described as “mummified”: the majority of the fossil leaves, trees, cones, etc. are not mineralized (i.e., there has been negligible mineral replacement of the vegetable tissue) and coalification has occurred only to a limited extent.
  • The site, which is the only one of its type in Canada, can be regarded in many ways.
  • Much of the cellulose fraction (the main component of fresh wood) is missing, and the molecular weight of what remains is less than one-tenth that of fresh wood (Grattan, 1991).

EROSION

  • The sedimentary deposits in which the forest is found are very poorly consolidated when unfrozen, a situation that favours rapid erosion in the harsh northern environment, “a terrain in which disintegration is at a maximum and decomposition at a minimum” (Ray, 1951:200).
  • Wind causes direct erosion or ablation of the site as is seen in Fig. 2, which shows dust being lifted hundreds of meters into the air (and also the scalloped shape of the west end of the Hill) during a severe windstorm in 1988.
  • This much-studied phenomenon is caused by the formation of cracks, which are evident at the edges of polygons.
  • At ground level, moisture content changed very abruptly from ca. 37% to 8% in partially buried wood.
  • These observations explain why buried fossil wood remains intact and does not fragment, but exposed wood fragments, delaminates and warps.

Erosion Markers

  • Two types of markers were placed in July 1988: these were termed “floating” and “permanent” (Fig. 6).
  • Usually this left about 0.3 m projecting above ground.
  • Placed at known distances from the fixed markers, these floating markers consist of 15 cm2 marine plywood sections with 0.3 m × 10 mm dowels driven through the centre at right angles.
  • Four sets of markers in arrays were placed in different areas of the hill (Fig. 7).
  • All distances between markers were measured by steel tape held parallel to the ground surface.

Ground Survey

  • Several reference points (also known as “trig. points”) were established on the high spots overlooking stump exposures on Fossil Forest Hill and on the hills to the south and east.
  • For charting stumps and logs, a theodolite (1989, 1992 surveys) or alidade and plane table (1988 survey) was established at each reference point overlooking exposures.
  • The software allows maps of any scale to be drawn, and also permits the selection of any specific area for enlargement.
  • In 1988 a plane table/alidade survey of the upper exposure at the east end of Fossil Forest Hill was completed.

Erosion

  • None of the permanent markers, which are spaced at 10 m intervals, moved in relation to one another (within ca. 0.01 m).
  • At certain locations, particularly in flatter regions, accretion (i.e., accumulation of wind-blown sand) also occurs.
  • This proved very unreliable, as the data had to be corrected because of errors in the readings from the device.
  • In the A range at the east end of the Hill, where an extended array of floating markers goes into a steeply declining and totally unconsolidated slope, average total movement was 33 cm by 1992.

CONCLUSIONS

  • The site is eroding, at least 3 mm per year on average, with erosion of slopes occurring more rapidly, particularly on the north side of the Hill, and much less erosion in the flatter regions.
  • The authors believe that scientists must continue to investigate the site, and that visitors ought to have access to see it.
  • While there may be some validity in these arguments, their observations show that exposed stumps deteriorate faster than those which are covered up.
  • It is worth emphasising that wood shrinks regardless of the method of drying, and it is their observation that the fossil wood, having lost its elasticity, has very limited tolerance for dimensional change.
  • The authors have tried to record the site and changes in it by both ground survey and aerial photography.

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ARCTIC
VOL. 48, NO. 4 (DECEMBER 1995) P. 342 353
Erosion of the Geodetic Hills Fossil Forest, Axel Heiberg Island, Northwest Territories
C. BIGRAS,
1
M. BILZ,
1
D.W. GRATTAN
1
and C. GRUCHY
1
(Received 23 February 1994; accepted in revised form 12 June 1995)
ABSTRACT. Studies on the erosion of the Geodetic Hills Fossil Forest on the east side of Axel Heiberg Island, Northwest
Territories have indicated that erosion by wind averaged a depth of 1.3 cm for the period 1988 to 1992. The fossil wood and leaf
litter tend to dry on exposure, resulting in shrinkage and fragmention—sometimes in less than a year. Frost, especially at the
boundaries of polygons, repeatedly compresses and disrupts the fossil-bearing strata. Erosion by water takes place as rills on the
sides of hills. Solifluction displaces surface sediment on the sides of the hills in the range of 6 to 45 cm per year. In the last few
years the physical disruption of stumps, tree trunks and forest mat has been caused mainly by people: by walking on the site, by
excavating it, and by flying over and landing helicopters on it. Natural processes—including wind, freezing and thawing, rainfall,
and wandering animals—also cause damage.
In 1992, 62 stumps recorded in the 1988 survey (ca. 10% of the total) could not be relocated. There are problems in accounting
for this discrepancy, because only a few stumps are known to have been removed by investigators for study, and it seems unlikely
(although it is possible) that others may have been removed by unknown visitors. Some of the “missing” stumps may still be
present, but disturbance in the surface sediment caused by scientific excavation or wind-driven accretion have made them
untraceable. Vestigial stumps may simply have weathered away in the period between surveys, and finally some of the losses may
be accounted for by errors in the initial surveying.
Since preservation is important both for long-term scientific interpretation and for public access, the site should be better
managed. The authors advocate that the site be managed by the Canadian Parks Service as an annex to Ellesmere Island National
Park Reserve.
Key words: fossil forest, Axel Heiberg Island, wood, leaf litter, erosion, preservation
RÉSUMÉ. Des études sur l’érosion de la forêt fossile des collines géodésiques du côté est de l’île Axel Heiberg dans les Territoires
du Nord-Ouest ont révélé que l’érosion éolienne était d’en moyenne 1,3 cm au cours de la période allant de 1988 à 1992. Le bois
et la couche de feuilles mortes fossiles ont tendance à sécher s’ils sont exposés aux éléments, ce qui aboutit au retrait et à la
fragmentation — parfois en moins d’un an. Le gel, en particulier aux limites des polygones, comprime et disloque les strates
fossilifères de façon répétée. L’érosion hydrique se produit sous forme de rigoles sur les pentes des collines. La solifluxion déloge
les sédiments de surface sur les pentes des collines à une vitesse de 6 à 45 cm par an. Au cours des dernières années, la perturbation
physique des souches, des troncs d’arbre et du tapis forestier a été causée principalement par les humains: piétinement et
excavation du site, survols et atterrissages des hélicoptères. Les processus naturels — y compris le vent, le gel et dégel, les
précipitations et le déplacement des animaux — causent également des dommages.
En 1992, 62 souches consignées dans le relevé de 1988 (environ 10 p. cent du total) n’ont pu être retrouvées. On a de la difficulté
à expliquer cet écart, car on sait que quelques souches seulement ont été enlevées par les chercheurs pour effectuer leurs travaux,
et il semble peu probable (bien que ce soit possible) que d’autres souches aient été enlevées par des visiteurs inconnus. Il se peut
que certaines des souches «absentes» soient toujours présentes, mais la perturbation des sédiments de surface causée par des
excavations scientifiques ou l’accrétion éolienne fait qu’elles sont impossibles à retracer. Des souches résiduelles ont peut-être
tout simplement été détruites par les éléments durant les périodes entre les relevés, et finalement, certaines des pertes peuvent être
expliquées par des erreurs dans le relevé initial.
Vu que la conservation est importante à la fois pour l’interprétation scientifique à long terme et pour l’accès du public, le site
devrait être mieux géré. Les auteurs recommandent que la gestion en soit remise au Service canadien des parcs, en tant qu’annexe
à la réserve de parc national de l’île-d’Ellesmere.
Mots clés: forêt fossile, île Axel Heiberg, bois, couche de feuilles mortes, érosion, conservation
Traduit pour la revue Arctic par Nésida Loyer.
1
Canadian Conservation Institute, Department of Canadian Heritage, 1030 Innes Road, Ottawa, Ontario K1A 0M5, Canada
© The Arctic Institute of North America
INTRODUCTION
The discovery in August 1985 of the fossil forest at Geodetic
Hills on Axel Heiberg Island, 79˚55'N, 89˚02'W, (Fig. 1)
sparked much academic and popular interest not only because
of its large size, but also because of the remarkable nature of
the fossils preserved there. Fossil forests have been defined as
“groups of preserved tree stumps found generally in growth

Many of the initial specimens recovered for the museum—
which included a tree stump, cones, and sections of leaf
mat—were very fragile, and some tended to disintegrate after
removal from their arctic environment to the laboratory.
While some collectors have found fossil specimens from this
site have sufficient physical integrity for scientific study,
their fragile condition is unsuitable for the stringent require-
ments of very long-term preservation in museums, where
even under the most carefully controlled conditions it is
impossible to prevent some physical or environmental distur-
bances from occurring. For these reasons, the Canadian
Conservation Institute, (CCI) was invited to become in-
volved in the project. The museum was also concerned with
minimizing damage to the fossil forest site. In response to this
request, CCI has attempted to monitor some of the changes
that are taking place. For six years, we have studied the effect
of the natural environment, as well as the impact of people.
This article reports and comments upon the initial results of
our work. Questions about the stability and integrity of the
site are being answered through an on-site monitoring pro-
gramme. This includes photography and mapping of stumps
and logs, aerial photography, and monitoring of erosion
markers placed in sensitive locations.
Scientists from CCI visited the site regularly from 1987 to
1992. In addition, several programmes of laboratory work
have been undertaken to analyze the specimens collected and
to develop new conservation procedures for their stabilization.
THE FOSSIL FOREST SITE
Although the site has been extensively described in other
publications (Christie and McMillan, 1991), a brief descrip-
tion is useful here. The site contains the remains of ancient
Tertiary forests (ca. 45 million years old), and several layers
of forest “floor” have been exposed in a state that is remark-
ably undisturbed despite the passage of time. The forest
remains are abundant. Many large tree stumps project from
the ground, and several periods of forest growth are evident
in forest litter containing strata interspersed with sands and
silt deposits (Francis and McMillan, 1987; Francis, 1991;
Ricketts, 1991). Tree stumps and forest litter, including
cones, seeds and leaves, have remained undisturbed for
millions of years. The trees include several species which
likely would have grown in warm and wet conditions. Exam-
ples are Glyptostrobus sp. and Dawn Redwood (Metasequoia
glyptostroboides).
The site is remarkable for the unusual condition of the
specimens that are commonly described as “mummified”: the
majority of the fossil leaves, trees, cones, etc. are not miner-
alized (i.e., there has been negligible mineral replacement of
the vegetable tissue) and coalification has occurred only to a
limited extent. The ash content of a sample of mummified
wood, a useful indicator of the degree of mineralization, is
reported as being about 1% by weight by Grattan (1991) and
up to 5% by Obst et al. (1991). This compares with approxi-
mately 0.2% to 0.5% for fresh wood. Petrified wood can have
FIG. 1. Map showing Fossil Forest location.
position” (Christie and McMillan, 1991:xiii). However, the
fossil forest in question has more than stumps in growth
position: the forest mat in which they are still rooted is
preserved, so that all the constituents are distinct and recog-
nizable. In some locations, the forest mat has the appearance
of relatively fresh material. Since 1985 when James Basinger,
a palaeobotanist from the University of Saskatchewan, iden-
tified mummified wood and forest mat, researchers have
observed a wide range of species and plant specimen types,
including leaves, seeds, cones, tree stumps, tree trunks and
branches as well as pollen and fungi. The results of
multidisciplinary investigations begun in 1987 and coordi-
nated by R.L. Christie of the Geological Survey of Canada
(GSC) have been published in a special volume (Christie and
McMillan, 1991). Since 1987, work has continued on the
identification and analysis of fossil specimens (Basinger,
1991; Lepage, 1993).
The site, which is the only one of its type in Canada, can
be regarded in many ways. It is an assemblage of specimens,
a preserved environment, a time capsule, or a gigantic refrig-
erated repository for specimens. It can also be seen simply as
a source of data. Each of the circa 27 strata containing leaf
litter or wood represents a period of forest growth. Each
preserves a particular group of botanical specimens and a
particular spatial arrangement of the preserved plants. The
site is of great value for its variety and number of plant
species, for the disposition of fossils within specific periods
of time, and for its record of how the vegetation changed with
time. The variation in species distribution between leaf mat
layers may also give information about climatic change.
From the species distribution, it is possible to reconstruct the
forests which grew on this site (Francis and McMillan, 1987;
Basinger, 1991; Francis, 1991; McIntyre, 1991; Lepage, 1993).
In 1986 the National Museum of Natural Sciences (now
the Canadian Museum of Nature) became interested in as-
sembling collections and interpreting the site for the public.
FOSSIL FOREST EROSION • 343

344 C. BIGRAS et al.
FIG. 2. A “sandstorm” in the Fossil Forest, 1988.
mineral content up to 100% (i.e., complete replacement of
organic material with minerals) with correspondingly high
ash content, depending on the minerals present. Although
these fossils represent some of the best-preserved Eocene
specimens known, it is incorrect to consider them
undeteriorated or like “fresh wood.” Much of the cellulose
fraction (the main component of fresh wood) is missing, and
the molecular weight of what remains is less than one-tenth
that of fresh wood (Grattan, 1991). Furthermore, the wood is
typically crushed (Grattan and Drouin, 1987) and the cell
structure distorted (Young, 1991). The mummified condition
also presents some challenging conservation problems.
Specimens remain wet while buried; when they dry after
removal from their wet environment, they become exceed-
ingly vulnerable to rapid deterioration. The wood shrinks in
the low arctic humidity and may crack apart. Even the merest
touch of a soft brush on a dry cone or leaf is enough to dislodge
fragments or cause crumbling. At the beginning of the project,
in 1986, there were no conservation procedures available for
preservation. New preservation techniques (such as parylene
deposition) have since been developed or adapted to preserve
these specimens (Grattan, 1991). These new techniques al-
lowed an entire collection to be treated for the Canadian
Museum of Nature. The work reported here, however, is not
concerned with individual specimens, but with the whole site.
The site consists mainly of exposures in a hill referred to
as “Fossil Forest Hill” or “The Hill” in the following text.
Related sites, considered part of the fossil forest, occur in the
surrounding hills where strata from the same levels are
exposed. Major exposures occur in a hill to the east of Fossil
Forest Hill, referred to as “The East Hill.”
EROSION
The sedimentary deposits in which the forest is found are
very poorly consolidated when unfrozen, a situation that
favours rapid erosion in the harsh northern environment, “a
terrain in which disintegration is at a maximum and decom-
position at a minimum” (Ray, 1951:200). Initial examination
identified the following causes of erosion or disruption of the
site and of loss or damage to specimens: 1) wind; 2) frost action;
3) water, leading to solifluction and mud flow; and 4) disrup-
tion by people, wandering animals, and aircraft wind-blast.
Wind causes direct erosion or ablation of the site as is seen
in Fig. 2, which shows dust being lifted hundreds of meters
into the air (and also the scalloped shape of the west end of the
Hill) during a severe windstorm in 1988. Wind speeds of up
to 90 km/h were measured at valley floor level, and speeds
were substantially greater on the hilltops. During the storm,

FOSSIL FOREST EROSION • 345
the wind rapidly removed surface leaf litter and sand. Perma-
frost prevents dune formation in the poorly consolidated hills
of the fossil forest region and keeps the active zone (i.e., the
portion of the ground above the permafrost) cold and wet,
which helps minimize wind ablation.
The most obvious effect of frost is the formation of
patterned ground (tundra polygons). In areas where consoli-
dation of the ground is very poor, polygon formation is not
observed. However, at the west end of the site where there is
a large area of exposed leaf mat, rectangular frost polygons
are present. This much-studied phenomenon is caused by the
formation of cracks, which are evident at the edges of poly-
gons. These cracks fill up with water during thaw and refreeze
to form ice wedges. Wedges prevent the reexpansion of
enclosed units in the active zone and thus continually enlarge
by as much as 1.5 mm per year (Drew and Tedrow, 1962). The
result of this repeated compression is the disruption of depos-
its along the boundaries of tundra polygons. In the west
region of Fossil Forest Hill, where a thick (ca. 30 cm) layer of
leaf mat is exposed, the polygons are very regular squares,
approximately 7 m
2
, and the cracks were measured at about
1 m across. In a younger deposit of leaf litter nearby, the
polygons are slightly less uniform in size and form smaller
units (sides typically 1 m, cracks ca. 6 cm in width).
Water, as rain or snowmelt, is not a major source of direct
erosion. The surface of Fossil Forest Hill is quite porous, so
that water in light rainfall is absorbed. Interestingly, heavier
rain has been reported as only wetting the surface (Basinger,
pers. comm. 1993). It is argued that wet, clay-like surfaces
seal the active zone, which remains comparatively dry, while
surface water is lost as runoff. However, rills are observed
only in certain regions—usually at maximum slope. As seen
in the upper portion of Figure 3, a rill may originate at the top
of a hill, disappear as a more porous layer is encountered, and
then reappear. The movement of moisture through or over the
active zone as rainfall or as melt is clearly variable. Water
cannot penetrate the hill deeply, because the permafrost table
is ca. 20 cm below the surface. Annual precipitation in this
region is reported to be less than 100 mm, of which 30% to
40% falls as liquid precipitation (Maxwell, 1981). During the
spring thaw the erosion channels, which occur all around the
hill, become active. On the north-facing slopes of the hill,
some erosion channels have enlarged into collapse basins up
to 30 m in diameter (Fig. 4) with mud flows at the base. These
collapse basins are clearly increasing in size, but not at a
steady rate. Sudden collapse of the upper edges has been
observed after heavy rain. Solifluction is most noticeable at
the lower angles of slope at the base of the hill, where there
has been mass movement of water-saturated ground over the
permafrost table.
FIG. 3. Erosion channels on north side of Fossil Forest Hill. FIG. 5. This stump has been left exposed and vulnerable to drying out and cracking.
FIG. 4. Collapse basins on north side of Fossil Forest Hill.
The predominant causes of physical disruption are the
effects of wandering people and animals, excavation, and
hovering and landing helicopters. Footprints in the loosely
consolidated surface can easily survive twelve months and
may initiate erosion channels. Excavation, though necessary
for scientific studies, may disrupt spatial relationships among
specimens and certainly limits future interpretation of the
site. Unfilled excavation around stumps, as shown in Figure
5, leads to premature disintegration—although a contrary
argument (Basinger, pers. comm. 1993) has been advanced
that stumps exposed do not disintegrate, and that leaving

346 C. BIGRAS et al.
holes unfilled at least shows clearly where excavations have
been made. Helicopters cause tremendous downdraughts
which can blow leaf mat or loose sand and silt around. This
may accelerate degradation of stumps and logs as well as
scattering pieces of them away from their original location.
The above agents, by eroding or disrupting the hill, have a
severe effect on the exposed fossils. There is an abrupt change
in water content at the boundary between buried and exposed
mummified wood in the summer (Grattan, 1991). Field
measurements with a resistance moisture meter were carried
out on a partially buried trunk section (1.8 m length, 13 cm
×
20 cm cross-section) in a typical Fossil Forest Hill litter
deposit (Fig. 2). The upper 40 cm of the litter layer was
exposed and the remainder buried to a maximum depth of 33
cm in the active zone. At ground level, moisture content
changed very abruptly from ca. 37% to 8% in partially buried
wood. The buried wood therefore had a moisture content in
excess of the fibre saturation point, previously estimated as
18.9% (Grattan and Drouin, 1987), and the exposed wood
was surprisingly dry. In seasons other than the summer, the
exposed wood would certainly be much wetter, and in the
intermediate seasons it would undergo frequent cycles of
freezing and thawing.
It was also demonstrated (Grattan and Drouin, 1987) that
the mummified wood shrinks and expands in response to
absorption or desorption of moisture. Going from complete
dryness to the fibre saturation point, the wood expanded by
4% in each of the principal dimensions of wood (tangential,
radial and longitudinal), which is 11% volumetrically.
These observations explain why buried fossil wood re-
mains intact and does not fragment, but exposed wood
fragments, delaminates and warps. The mummified wood is
so degraded (by degradation of the polymeric structure of the
cellulose which gives wood its strength) that the wood has
lost its elastic properties. If it shrinks, it breaks. Continual
shrinkage and expansion caused by moisture absorption and
desorption cause the wood to fracture until it disintegrates
and is blown or washed away. These phenomena, to some
extent, also apply to leaf litter and other plant remains.
However, it is noteworthy that blocks of leaf mat tend to mesh
together and survive as intact units better than the surround-
ing silts and sands.
MEASUREMENTS AND MAPPING METHODS
Erosion Markers
Two types of markers were placed in July 1988: these were
termed “floating” and “permanent” (Fig. 6). Their purpose
was to measure wind erosion as loss of surface area and
movement of the active zone by frost or solifluction. Perma-
nent markers consist of 1.2 m sections of 12 mm diameter
steel rod (standard
1
/
2
" concrete reinforcing rod) driven into
the permafrost with at least 0.3 m penetration. Usually this
left about 0.3 m projecting above ground. The intention was
to provide semipermanent reference points to which changes
FIG. 6. A floating and a permanent marker. The partially covered floating
marker is direct evidence of accretion.
in surface level, encroachment of erosion channels and move-
ment of the floating markers could be related. We assume that
the permafrost remains stable, as reported by Ray (1951). A
larger number of floating markers were also installed. Placed
at known distances from the fixed markers, these floating
markers consist of 15 cm
2
marine plywood sections with
0.3 m
× 10 mm dowels driven through the centre at right
angles. The floating markers were intended to move with the
active zone if slippage or solifluction took place. The steel rod
markers were placed in rows, usually at 10 m intervals in the
flatter regions (i.e., within exposures) of the Hill. Wooden
floating markers (also at intervals of 10 m) were placed so as
to continue these arrays down the sides of the hill through
regions of maximum slope. A floating marker was placed at
ca. 30 cm from each steel marker. Four sets of markers in
arrays were placed in different areas of the hill (Fig. 7). Three
arrays (A, C and D) cross areas of exposed leaf litter and the
side of the hill. In one instance (C) the floating markers were
taken almost to valley floor level, and over both north and
south sides of the hill. One array of markers (B) was placed
in three parallel lines in the vicinity of the largest erosion
channel on the north side of Fossil Forest Hill. In all, 24 steel
rod markers and 60 floating markers were installed. All

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Journal ArticleDOI
Abstract: Lush forests, dominated by deciduous conifers, existed well north of the Arctic Circle during the middle Eocene (∼45 Ma). The Fossil Forest site, located on Axel Heiberg Island, Canada, has yielded a particularly rich assemblage of plant macro- and microfossils, as well as paleosols—all exquisitely preserved. Methods ranging from classical paleobotany, to stable-isotope geochemistry, have been applied to materials excavated from the Fossil Forest and have revealed layers of diverse conifer forests with a rich angiosperm understory that successfully endured three months of continuous light and three months of continuous darkness. Paleoenvironmental reconstructions suggest a warm, ice-free environment, with high growing-season-relative humidity, and high rates of soil methanogenesis. Methods to evaluate intraseasonal variability highlight the switchover from stored to actively fixed carbon during the short annual growing season.

79 citations


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Abstract: Dunarobba and Pietrafitta are two outstanding fossil sites, which provide us with a glimpse on central Italian palaeoenvironments during two different time spans. The still poorly dated Dunarobba succession is framed, mainly on the basis of continental mollusc biochronology, within the Piacenzian-Gelasian interval, whereas the Pietrafitta one is reliably dated to the Calabrian thanks to vertebrate biochronology. Here we add several new palaeobotanical data for the two sites and we provide for the first time an overview of the stratigraphic, sedimentological, palaeontological and palaeoenvironmental results so-far obtained. We also review the palaeobotanical evidence concerning the neighbouring sites of Cava Toppetti I/II, Fosso Bianco, Torre Picchio and Villa San Faustino. On the basis of the available datasets we conclude that the Dunarobba Fossil Forest, with several large conifer trunks in upright position, was produced by an ancient swamp vegetation dominated by Glyptostrobus europaeus, and including few other woody (Alnus, Cephalanthus, Cornus) and herbaceous (Carex, Cladium, Schoenoplectus) plants. Rich water-transported fruit and seed assemblages and pollen data indicate that the well-drained palaeoenvironments around the Dunarobba palaeo-swamp were covered by a forest having a floristic affinity to the modern Mixed Mesophytic Forests of East Asia, as proved by the occurrence of Cryptomeria, Eurya, Sinomenium, etc. The disappearance of the Glyptostrobus swamp forest was due to the establishment of well-drained palaeoenvironmental conditions, testified by a

35 citations


Journal ArticleDOI
Abstract: Polygon networks are usually described qualitatively as becoming more regular through time, but such a concept has yet to be demonstrated numerically. The aim of this study is to address this question quantitatively in order to determine if polygonal terrain networks actually become more regular as they develop. Spatial point pattern analysis (SPPA), which can quantify overall network geometries based on the randomness or regularity exhibited by the spatial arrangement of polygon-bounding trough intersections, was used at three ice-wedge polygon sites in the Canadian High Arctic. SPPA was applied in two ways: (i) on the present-day networks observed in the field; and (ii) on historical arrangements derived by distinguishing primary from secondary troughs. In all cases, the polygonal networks had undergone a statistically significant regularisation over the course of their development. Although the method was applied only to terrestrial ice-wedge polygons, such an approach may also be useful for interpreting the evolution of Antarctic sublimation polygons and geometrically similar polygonal networks on Mars. Copyright © 2012 John Wiley & Sons, Ltd. and Her Majesty the Queen in Right of Canada.

16 citations


Cites background from "Erosion of the Geodetic Hills Fossi..."

  • ...Although long-term climatic data are not available at these sites specifically, Bigras et al. (1995) report a mean annual temperature for the Expedition Fjord region of approximately 15 C and total annual precipitation of< 100 mm. Site TL1 (75 21’26.8"N 88 40’47.2"W) is located near Thomas Lee…...

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DOI
01 Jan 2018
Abstract: This paper is aimed to illustrate and discuss new data from the clayey deposits collected in the Dunarobba area (Umbria, central Italy), and to better understand some features of the “Fosso Bianco” Unit lacustrine stage inside the South Tiberino Basin, during its latest (presumably Early Pleistocene) phases. Data come from a newly cultivated quarry area (Cava Nuova), only partly considered in previous works; the new section extends well inside the deep lake depositional stage of Fosso Bianco Unit, previously not directly described in outcrop in the Dunarobba area, but only reported from well logs. Selected samples from the Cava Nuova section were analyzed from sedimentological, geotechnical, chemical, mineralogical and biostratigraphical point of view. Sedimentological and geotechnical analyses, including density measurements, particle-size analysis, Atterberg limits and organic matter content, as well as XRF and XRPD analyses, resulted the most suitable techniques to identify the main features, at least for prevailing clayey deposits. Facies analysis and sedimentological data lead to recognize a clear depositional transition from relatively deep to shallow lacustrine deposits, which was only rarely documented formerly through a single section. On the other hand, both geotechnical and mineralogical data indicate a compositional homogeneity for clay sediments, which does not correspond with facies lateral and vertical variability nor with palaeoenvironmental complexity. Despite its preliminary nature, this integrated method looks very promising to characterize the paleodepositional context, and some hypotheses on sediment source were also evaluated. Integrated data from Cava Nuova section, as well as minor well-logs in the immediate surroundings, were discussed and compared with existing data outcoming from the whole Dunarobba area. On the heels of the recent literature, this paper is aimed to put a new light on the complexity of the Fosso Bianco paleoenvironment.

2 citations


Cites background from "Erosion of the Geodetic Hills Fossi..."

  • ...Dunarobba is one of the few sites in the world yielding mummified and upright fossil forests, including (regardless to age) Axel Heiberg Island, in the Arctic region of Canada (45-40 Ma: Bigras et al., 1995; Williams et al., 2008), the Bukkabrany swamp cypress forest in Hungary (7.7-6.3 Ma: Kàzmér, 2008; Csaszar et al., 2009; Erdei et al., 2009; Gryc & Sakala, 2010; Erdei & Magyari, 2011), and the Stura di Lanzo Fossil Forest, in NW Italy (~3.0 Ma: Martinetto et al., 2007; Vassio et al., 2008)....

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  • ...…world yielding mummified and upright fossil forests, including (regardless to age) Axel Heiberg Island, in the Arctic region of Canada (45-40 Ma: Bigras et al., 1995; Williams et al., 2008), the Bukkabrany swamp cypress forest in Hungary (7.7-6.3 Ma: Kàzmér, 2008; Csaszar et al., 2009; Erdei et…...

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  • ...On the bases of ostracofauna, Spadi (2018) and Spadi et al. (2018b) proposed deposits of the Fossil Forest area are almost coeval to the Ponte Naja Unit (2.2-2.0 Ma: Abbazzi et al., 1997; Pontini et al., 2002)....

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Journal ArticleDOI
Abstract: On Axel Heiberg Island, Nunavut, Canada, a banded vegetation pattern occurred on a hillside where patterned ground and unidirectional abiotic fluxes, such as downslope water flow or wind, were not present. The parent material was the obvious source of the plant pattern, as the soils occurred on five distinct types of alluvial deposits. To examine the observed pattern, plants were inventoried and soils were sampled in July 1999. Twelve vascular species of plants, but no non-vascular species, were present at the site. Neither water, often thought to limit plant distribution in the High Arctic, nor any of the other measured soil variables, predicted plant abundance. The best predictor of plant abundance, based on regression tree analysis, was total soil nitrogen; however, higher plant density was associated with lower nitrogen. The five soil types differed in plant density and soil properties. Even though the sand soil always had soil nutrients equal to or lower than the blocky clay soil, the sand a...

1 citations


Cites background from "Erosion of the Geodetic Hills Fossi..."

  • ...Erosion by wind and mass wasting has been measured at 0.3 cm yr 1 in flat areas and up to 11 cm yr 1 in steeper areas (Bigras et al., 1995)....

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References
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Journal ArticleDOI
01 Jan 1981-Arctic
Abstract: As a result of a comprehensive assessment of the climate of the Canadian Arctic Islands and adjacent waters, five climatic regions were identified. The regional boundaries were delineated by an analysis of the influence of the major climatic controls while further regional subdivisions were arrived at through consideration of the fields of the standard observed meteorological elements. Short discussions of the climatic characteristics of each sub-region are given and tables outlining values of selected climatic elements are presented. A brief discussion of climatic change across the entire area is included. Key words: Canadian Arctic Islands, climate, climatic change, meteorology

121 citations


ReportDOI
01 Jan 1991

102 citations


"Erosion of the Geodetic Hills Fossi..." refers background in this paper

  • ...Since 1987, work has continued on the identification and analysis of fossil specimens (Basinger, 1991; Lepage, 1993)....

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  • ...From the species distribution, it is possible to reconstruct the forests which grew on this site (Francis and McMillan, 1987; Basinger, 1991; Francis, 1991; McIntyre, 1991; Lepage, 1993)....

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ReportDOI
01 Jan 1991

60 citations


"Erosion of the Geodetic Hills Fossi..." refers background in this paper

  • ...From the species distribution, it is possible to reconstruct the forests which grew on this site (Francis and McMillan, 1987; Basinger, 1991; Francis, 1991; McIntyre, 1991; Lepage, 1993)....

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ReportDOI
01 Jan 1991

55 citations


"Erosion of the Geodetic Hills Fossi..." refers background in this paper

  • ...Many large tree stumps project from the ground, and several periods of forest growth are evident in forest litter containing strata interspersed with sands and silt deposits (Francis and McMillan, 1987; Francis, 1991; Ricketts, 1991)....

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  • ...From the species distribution, it is possible to reconstruct the forests which grew on this site (Francis and McMillan, 1987; Basinger, 1991; Francis, 1991; McIntyre, 1991; Lepage, 1993)....

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Frequently Asked Questions (1)
Q1. What have the authors contributed in "Erosion of the geodetic hills fossil forest, axel heiberg island, northwest territories" ?

There are problems in accounting for this discrepancy, because only a few stumps are known to have been removed by investigators for study, and it seems unlikely ( although it is possible ) that others may have been removed by unknown visitors. The authors advocate that the site be managed by the Canadian Parks Service as an annex to Ellesmere Island National