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This paper examines chronological methods for reoccupied archaeological sites with surface arrangements of stone features in the alpine tundra. It is challenging to interpret feature dates in the t...

In this study, the lichenometry studies of the Hoksar Glacier valley in Kashmir Himalaya, India supported by the extensive ground- and remote sensing-based glacial geomorphological mapping enabled ...

Independent dating of closely-spaced moraines on the west Breiðamerkurjökull foreland is used to test the accuracy of the size frequency (SF) and largest lichen (5LL) lichenometric dating techniques. The 5LL technique derived the most accurate ages for three undated moraines within the dated sequence but growth rates and lag times produced by the two methods (5LL = 0.71 mm yr-1 and 11 years; SF = 0.64 mm yr-1 and 7 years) were not significantly different. We therefore reject previous conclusions that any one technique is demonstrably inferior to the other, at least for dating glacial landforms created over the last 130 years in SE Iceland. Comparisons of climate trends and recession rates indicate that air temperature anomalies, particularly those of the summer, are the strongest driver of glacier retreat. No clear relationship between NAO trends and glacier retreat were identified, although a positive and/or rising trend in NAO is associated with the slowing of ice retreat overall, and the marked readvances of the mid-1950s, mid-1970s and mid-1990s are all coincident with positive and/or rising NAO 5yr moving averages. Summer and annual temperature trends, not the NAO, clearly show that recent accelerated global warming is driving the marked recession of the period 1995-2015. Over the last 100 years temperature has been the major driver of glacier terminus oscillations at west Breiðamerkurjökull but it is clear that extreme decreases in winter precipitation (i.e. 1960-73) have the potential to increase retreat rates significantly even during times of below average annual temperatures.

We compile new and previously published lichenometric and cosmogenic 10Be moraine ages to summarize the timing of Holocene glacier expansions in the Brooks Range, Arctic Alaska. Foundational lichenometric studies suggested that glaciers likely grew to their Holocene maxima as early as the middle Holocene, followed by several episodes of moraine building prior to, and throughout, the last millennium. Previously published 10Be ages on Holocene moraine boulders from the north-central Brooks Range constrain the culmination of maximum Holocene glacier advances between 4.6 ka and 2.6 ka. New 10Be ages of moraine boulders from two different valleys in the central Brooks Range published here show that maximum Holocene glacial extents in these valleys were reached by 3.5 ka and ca. 2.6 ka, supporting previous studies showing that Holocene maximum, or near-maximum, glacial extents in the Brooks Range occurred prior to the Little Ice Age. However, in-depth reconciliations between glacier extent and local an...

Mani walls, Buddhist sacred walls constructed of carved blocks, are common in Langtang Valley, Nepal Himalaya. Fieldwork in 2009–2015 documented all 80 mani walls, including all occurrences of the lichen Rhizocarpon geographicum. According to local informants, the mani walls were constructed 400–600 years ago, and the original mani wall was in the village of Ghoratabela. Based on the indirect method, the oldest lichen on a mani wall dated only to 1942, which, within modeling error, was concurrent with the 1934 earthquake, the last major earthquake in Nepal prior to the Gorkha earthquake of 25 April 2015. In November 2015 it was found that 15% of mani walls could not be located and 20% were severely damaged. The original mani wall had apparently been reconstructed 170 m from its previous location. In two severely damaged and three fully intact mani walls, large lichens (12–49 mm) with unhealthy appearance were found that were not previously present. The most likely explanation was that the three i...

Lichenometric dating (lichenometry) involves the use of lichen measurements to estimate the age of exposure of various substrata. Because of low radial growth rates and considerable longevity, species of the crustose lichen genus Rhizocarpon have been the most useful in lichenometry. The primary assumption of lichenometry is that colonization, growth and mortality of Rhizocarpon are similar on surfaces of known and unknown age so that the largest thalli present on the respective faces are of comparable age. This review describes the current state of knowledge regarding the biology of Rhizocarpon and considers two main questions: (1) to what extent does existing knowledge support this assumption; and (2) what further biological observations would be useful both to test its validity and to improve the accuracy of lichenometric dates? A review of the Rhizocarpon literature identified gaps in knowledge regarding early development, the growth rate/size curve, mortality, regeneration, competitive effects, colonization, and succession on rock surfaces. The data suggest that these processes may not be comparable on different rock surfaces, especially in regions where growth rates and thallus turnover are high. In addition, several variables could differ between rock surfaces and influence maximum thallus size, including rate and timing of colonization, radial growth rates, environmental differences, thallus fusion, allelopathy, thallus mortality, colonization and competition. Comparative measurements of these variables on surfaces of known and unknown age may help to determine whether the basic assumptions of lichenometry are valid. Ultimately, it may be possible to take these differences into account when interpreting estimated dates.

Buddhist sacred walls, called mani walls, are common between Langtang Village and Kyanjin Gompa in Langtang Valley, Nepal Himalaya. The objective of this study was to interview local informants about the mani wall traditions and to use lichenometry to resolve discrepancies regarding the maintenance of the mani walls. The maximum diameters of the lichen Rhizocarpon geographicum were measured on each of 24 mani walls. An apparent lichen growth curve was developed using five sources of indirect data, including the foundation of one stupa (sacred monument) and two locations of former ice cover, for which ages were obtained from local informants, and two debris ridges that had been dated by 10Be. The direct method was pursued by measuring the maximum diameters of 20 lichens in remote locations in both 2009 and 2014. Based on the indirect method, the mani walls are cleaned on a geometric mean cycle time of 13 years. The direct and indirect methods yield equivalent ages when the minimum direct growth ra...

Botanists make yearly measurements of lichen sizes that describe highly variable radial expansion of young, and old, hizocarpon subgenus hizocarpon that is a function of thallus size and age. Such ...

Contemporary variants of the lichenometric dating technique depend upon statistical correlations between surface age and maximum lichen sizes, rather than an understanding of lichen biology. To dat...

This study presents a growth curve developed from direct and indirect growth rates of Rhizocarpon geographicum lichens from study sites on Mounts Baker, Rainier, Adams, and Hood in the northern Cascade Range of the western USA. Our observations of direct growth rates are based on 31 measurements of 11 lichens growing on different surfaces. This direct growth rate dataset is complemented by indirect growth rates based on measurements of the largest lichen observed on 20 different surfaces over 24–33-yr periods. The direct and indirect datasets produce statistically indistinguishable mean radial growth rates of 0.48 and 0.50 mm yr−1, respectively. Statistical analysis of zero and first order fits of our growth rate data suggests that lichen growth is best characterized by the average of our mean growth rate (zero order) models at 0.49 mm yr−1. Our revised growth curve for the study area extends the applicable range for dating rock surface in the study area to the seventeenth century, approximately 175 years longer than previous calibrated curves.

The Little Ice Age behaviour of glaciers in the central British Columbia Coast Mountains, Canada, was described by conducting lichenometric surveys of Rhizocarpon spp. found on recently deposited moraines in the Kitimat and Pacific ranges. At Pattullo Glacier in the southern Kitimat Range, surveys across four sets of nested lateral moraines describe advances prior to the late thirteenth century, 1550–1610, 1680–1710, and 1850 ad. In the Monarch Icefield area in the northern Pacific Range, Little Ice Age moraines stabilized prior to 1380–1430 ad, the mid-seventeenth and mid-eighteenth centuries, and in the mid-nineteenth century. The timing of these moraine-building episodes corresponds closely to the intervals of glacier expansion recorded in complementary studies in the region. These findings indicate that most glaciers in the region reached their maximum downvalley Little Ice Age extent prior to 1780 ad, and suggest that climate forcing likely contributed to regionally synchronous glacier fluctuations.

The recently observed recession of glaciers on King George Island is associated with decades of climate warming in the Antarctic Peninsula region. However, with only 60 years of glaciological observations in the study area ages of the oldest moraines are still uncertain. The goal of the study was to estimate ages of lichen colonization on the oldest moraines of the Ecology and White Eagle Glaciers on King George Island and on the Principal Cone of Penguin Island volcano. The first lichenometric studies on these islands from the late 1970s used rates that had about four to five times slower Rhizocarpon growth rates. We re-examined the sites and measured 996 thalli diameters to establish the surface ages. To estimate the age we used (1) long-term Rhizocarpon lichen group growth rates established by authors using data from a previous lichenometric study on King George Island, and (2) previous data of lichen growth rates from other sub-Antarctic islands. Our results suggest growth rates between 0.5 and 0.8 mm yr–1. According to these rates the ages of the oldest moraine ridges are of the Little Ice Age and were colonized at the beginning of the twentieth century. The mid-twentieth century age of lichen colonization on the historically active Penguin Island volcano might support the date of the last eruption reported by whalers in the end of the nineteenth and the beginning of the twentieth century.

Directly measured growth rates of two lichens (Pseudephebe minuscula and Rhizocarpon sections Rhizocarpon and Superficiale) from Svalbard made over a two-decade interval (1984–2007) are presented. Growth rates were determined by measuring the change in area of the lichen thalli from digital images and converting area to diameter. Pseudephebe diameter growth rates ranged from 0.2 to 1.5 mm yr−1 and Rhizocarpon grew 0.05 to 0.30 mm yr−1. Growth rates of both are a function of thalli size—growth rates increase with increasing thallus size up to 70 mm diameter for Pseudephebe and 30 mm diameter for Rhizocarpon. While these directly measured growth rate results are consistent with other recent directly measured lichen growth studies, they are not consistent with indirectly determined age-size curves that show a negative correlation between size and growth rate (i.e., rapid “great growth” followed by slower “linear growth”). We explore several reasons to explain the apparent discrepancy between directl...

Matthews, J.A. and Trenbirth, H.E., 2011. Growth rate of a very large crustose lichen (Rhizocarpon subgenus) and its implications for lichenometry. Geografiska Annaler, Series A: Physical Geography...

Lichenometric measurements using Rhizocarpon ssp. were carried out on 20 talus slopes in the cirques of the Finstertal valley (Austria) at an elevation of 2300–3000 m a.s.l. The aim was to assess a...

Climatic interpretations of recent glacier fluctuations rely on ice-extent chronologies developed from lichenometric ages of Holocene landforms. However, lichenometry requires time- and resource-consuming field surveys, which limit our understanding of glacier chronologies, especially in remote locations. This study presents a rapid, coarse, a priori approach to predicting new field sites where lichenometry can be applied. Geologic, geographic, climatic, and landcover data were used in spatial and supervised classification analyses to identify areas in the Cascade Range of Washington and northern Oregon with similar environmental conditions to those where lichenometric dating techniques had previously been applied. These results focus the attention of researchers to only 1100 km2, or 3%, of the broader Cascade Range study area. Though this study concentrates on the utility of lichenometry for dating recent glacier activity in the Cascade Range, the screening method presented is easily translatable to a va...

This study aims to characterize the morphology and contemporary floodplain deposit dynamics within a braided sandur system in upper Erdalen, a steep U-shaped valley in western Norway. The braided sandur system is fed by two tributary valleys connected to the Jostedalsbreen Ice Field. Based on field observations, two different sub-systems can be identified within the braided sandur system: fine-grained to sandy flood sediments down-valley, and coarser, gravelly deposits in the upper part. A combination of different methods is applied for studying sediment dynamic processes within the braided sandur system (sedimentological and stratigraphic analyses, 14C dating, dendrochronology and lichenometry). The coarser deposits are interpreted as originating from the Little Ice Age advance in Erdalen. Preliminary results indicate that the floodplain sediments were deposited after the Little Ice Age advance. Different sedimentary facies types are present and different phases of flooding can be identified. Within the entire braided sandur system, multiple sub-systems characterized by different levels of process intensities exist.

This paper emphasizes the importance of studying diffuse rock debris accumulation in the far distal part of colluvial cones with the aim of de- fining the spatial distribution and frequency of ex- treme snow avalanches. These deposits are located at some distance from the slope and have rarely been described in the literature. The field based methods used in this study confirm the snow- avalanche origin of these deposits by (i) character- izing the distribution of the deposits along the col- luvial cones and to their furthest extent, some way from the foot of the slope, and (ii) clearly defining the orientation of the long axis of the furthest and largest boulders as parallel with the main cone axis. A relative age of the deposits is obtained by assess- ing the vegetation cover of the boulder surfaces and by measuring the rock hardness using a Schmidt hammer. The study concludes that there were fre- quent extreme snow avalanches which have oc- curred since the Little Ice Age, and that they have decreased in magnitude during the past decade.

In Alaska, lichenometry continues to be an important technique for dating late Holocene moraines. Research completed during the 1970s through the early 1990s developed lichen dating curves for five...

Glaciers in small mountain cirques on South Georgia respond rapidly and sensitively to changes in South Atlantic climate. The timing and rate of their deglaciation can be used to examine the impact that nineteenth- and twentieth-century climate change has had on the glacial dynamics and terrestrial ecosystems of South Georgia. As part of a reconnaissance study in Prince Olav Harbour (POH), South Georgia, we measured the size of lichens (Rhizocarpon Ram. em Th. Fr. subgenus. Rhizocarpon group) on ice-free moraine ridges around two small mountain cirques. Our aims were twofold: first, to provide age estimates for lichen colonization, and hence, deglaciation of the moraine ridges, and second, to examine the potential of applying lichenometry more widely to provide deglacial age constraints on South Georgia. In the absence of lichen age-size (dating) curves for South Georgia, we use long-term Rhizocarpon lichen growth-rates from recent studies on sub-Antarctic Islands and the western Antarctic Peninsula to calculate likely age estimates. These data suggest ice retreat from the two outermost moraines occurred between the end of the 'Little Ice Age' (post c. 1870) and the early twentieth century on South Georgia. Lichen colonization of the innermost moraines is probably related to glacier retreat during the second half of the twentieth century, which has been linked to a well-defined warming trend since c. 1950. Patterns of possible nineteenth- and twentieth-century glacial retreat identified in POH need to be tested further by establishing species- and site-specific lichen age-size (dating) curves for South Georgia, and by applying lichenometry to other mountain cirques across South Georgia.

This paper presents new lichenometric population data from the Antarctic Peninsula (67°S), and describes a new approach to lichen growth-rate calibration in locations where dated surfaces are extremely rare. We use historical aerial photography and field surveys to identify sites of former perennial snowpatches where lichen populations now exist. As an independent check on lichen mortality by snowkill, and the timing of snow patch disappearance, we use a positive-degree day (PDD) approach based on monthly climate data from Rothera Research Station. We find that maximum growth rates for lichens

This paper presents a critical review of previous lichenometric and lichen growth studies in southern parts of West and East Greenland. These studies include classic work from around Sondre Stromfj...

The reliability of lichenometric dating is dependent on a good understanding of lichen growth rates. The growth rate of lichens can be determined from direct measurement of growing lichens or indirect methods by measuring lichens growing on surfaces of known age, although there are limitations to both approaches. Radiocarbon (14C) analysis has previously been used in only a handful of studies to determine lichen growth rates of two species from a small area of North America. These studies have produced mixed results; a small amount of carbon turnover appears to occur in one of the species (Caloplaca spp.) previously investigated introducing uncertainty in the growth rate, while much higher carbon cycling occurred in another (Rhizocarpon geographicum), making the 14C approach unsuitable for estimating growth rates in the species most commonly used in lichenometric dating. We investigated the use of bomb-14C analysis to determine the growth rate of a different crustose species (Pertusaria pseudocorallina) common to Northern Europe. 14C-based growth rates were considerably higher than growth rates of morphologically similar species based on direct measurement made at locations nearby and elsewhere in the UK. This observation strongly suggests that a degree of carbon turnover probably occurs in Pertusaria pseudocorallina, and that bomb-14C analysis alone cannot be used to determine lichen age or absolute growth rates in this lichen species.

Lichenometry was used to study fluctuations of six glaciers in the Polar Urals over the last millennium (viz: IGAN, Obrucheva, Anuchina, Shumskogo, Avsiuka and Berga glaciers). In order to estimate the growth rate of Rhizocarpon subgenus Rhizocarpon lichens we used recently deglaciated surfaces as calibration sites. These sites, on glacier forelands, were dated using topographic maps, aerial photographs (from 1953, 1958, 1960, 1968, 1973, 1989), terrestrial photogrammetry, field photographs (from the 1960s to 2005), and satellite images (from 2000 and 2008). We also used pits and quarries abandoned between the 1940s–1980s and a road built in the early 1980s as calibration sites. Optimum diametral growth rates of Rhizocarpon subgenus Rhizocarpon are estimated by the new curve to be c. 0.25 mm/year for the last 100 years, assuming linear growth as deduced from the shape of other curves from northern Scandinavia. Due to the lack of old control points we used a reconstructed mass balance curve (from 1816 to 2008) to indirectly constrain the age of pre-twentieth-century moraines. The following moraine groups were identified near the modern fronts of glaciers: ablation moraines de-glaciated during the last 40 to 60 years; lateral moraines formed in the early twentieth century (largest lichen diameter (DLL) = 20 mm), ice-cored moraines, probably from the 1880s (DLL= 24–26 mm); moraines probably deposited in the middle of the nineteenth century and c. 200 years ago (DLL= 30–33 mm and 44–47 mm, respectively); as well as several more ancient moraines (DLL= 70 mm, 90 mm and 110–153 mm) deposited during glacier advances of almost identical extent. According to our tentative lichenometric-age estimates most moraines were formed during the last 450 years – consistent with upper tree-limit altitude variations previously identified for this region. Glacier fluctuations in the Polar Urals are in agreement with tree-ring based reconstructions of summer temperature spanning the last millennium, and are also in tune with glacier behaviour elsewhere in the Northern Hemisphere.

We mapped Little Ice Age (LIA) moraines in the Brooks Range to estimate former equilibrium-line altitudes (ELAs), and combined this information with available proxy temperature estimates to infer precipitation trends because little is known about precipitation changes associated with centennial-scale climate variability in the Arctic during the late Holocene. The Brooks Range, northern Alaska (68°N), hosts hundreds of extant glaciers that exhibit geomorphic evidence for multiple fluctuations in ice extent during the past millennium. Our lichenometric age estimates for LIA moraines in the forefields of five cirque glaciers in the Sagavinerktok River valley and Oolah Valley suggest two intervals of LIA moraine formation centered around a.d. 1250 and 1650. The outermost LIA moraine was mapped on aerial photographs for 114 relatively large (1.2 ± 0.5 km) and geographically simple glaciers along a 700-km-long transect following the range crest. At their maximum extent during the LIA, these glaciers we...

The endolithic lichen Lecidea auriculata is known to enhance rock surface weathering on the Little Ice Age moraines of the glacier Storbreen in Jotunheimen, central southern Norway. This s...

This review summarises lichen work in the temperate Southern Hemisphere. A brief historical overview of austral lichenology is presented from the earliest European voyages of discovery up to the present day. Current knowledge is outlined for Australia, New Zealand, South Africa, southern South America, the Southern Subpolar islands, and Antarctica. Biogeographical patterns, and the importance of lichens in nutrient cycling, habitat restoration, and monitoring of global change, are also discussed from an austral perspective.

Moraine ridges are commonly used to identify past glacier ice margins and so infer glacier mass balance changes in response to climatic variability. However, differences in the form of past ice mar...

Geografisk Tidsskrift, Danish Journal of Geography 108(1):143–151, 2008 Different field methods, which may result in lichen growth curves and lichenometric dating curves, respectively, are outlined and discussed. Emphasis is laid on various factors that need to be taken into consideration in order to avoid errors. The importance of having many control points and minimizing of heterogeneous habitat factors in establishing the sample areas are stressed. It is also important to be aware of some problems regarding the lichen taxa, which are commonly used for lichenometric purposes. A recent example of the application of this particular technique on a glacier foreland at the Mittivakkat Glacier on Ammassalik Island in South East Greenland is discussed.

Debris flows in the Gleivarhjalli area in northwestern Iceland occurred after a sudden and intensive snowmelt period during 10–12 June, 1999. The area, in the northwestern part of the town of Isafj...

Little Ice Age (LIA) moraines along the margins of Skalafellsjokull and Heinabergsjokull, two neighbouring outlet glaciers flowing from the Vatnajokull ice‐cap, have been re‐dated to test the relia...

A complex sequence of sawtooth moraines occurs on the proglacial foreland at Lambatungnajokull, southeast Iceland. These features reflect the pattern of deglaciation of a highly crevassed ice margin. The whole sequence documents a period of overall glacier recession exceeding 450 m. Dates have been interpolated for the formation of these moraines through the examination of aerial photographs and the application of lichenometry. The moraines formed annually between AD ∼1932 and 1950. Retreat rates were greatest between 1933 and 1939 and slowest between 1942 and 1944, as reflected by the spacing of annual moraine ridges. Differences in glacier recession rate from year to year are related to variations in mean summer air temperature. A rise in mean summer temperature of 1°C results in a retreat rate of ∼30 m yr−1. It is shown that annual moraine spacings are a suitable geomorphological proxy for annual net glacier balance and a potentially valuable source of paleoclimatic information.

The retreat of 293 glaciers in the Tien Shan Mountains (Kyrgyz Republic) from their maximum extent during the Little Ice Age (LIA) is estimated using aerial photographs from 1980 to 1985 and maps a...

A selective review of lichenometry as used to date Holocene moraines in five diverse regions of Alaska and in southeastern Kamchatka suggests that growth curves for this North Pacific area may be improved by attention to several factors. These included lichen identification, control point number and distribution, radiocarbon calibration, alternative curve models, and compatibility of lichen growth rate with climate. Support for control points presented for Kamchatka and published for Alaska areas will benefit from supplementary control at and beyond the break from the great growth curve segments of the last centuries. With regard to alternative—linear, logarithmic, and composite curve—models drawn for the published lichenometric data, the composite (logarithmic and linear composite models) appear the best fit for the Brooks Range and Wrangell–St. Elias areas of slow growth and continental interior climates. Calibration of 14C ages make minor changes in well-controlled curves, but differences may ...

Two lichenometric techniques were compared in a study of lichen growth–rate in northern Sweden. The first technique, based on the maximum lichen diameter on glacier moraines, was identical to the t...

This paper presents the results of a lichenometric and dendrochronological study of the recent retreat history of Glaciar Nef, an eastern outlet glacier of the Hielo Patag6nico Norte. A 600-yr tree regeneration time, based on maximum tree age in the ancient forest, suggests that the forest-clad lateral moraines in the valley, southeast of the 19th century terminal moraine system, were formed some time before A.D. 1370. Dating estimates suggest that retreat from a 19th century maximum began around 1863, a decade or two earlier than the date established for other glaciers in the region, with glacier thinning near the ice front averaging 1.11 m yr- between 1863-1881. After 1884, retreat seems to have slowed, with glacier thinning averaging 0.09 m yr-~. Lichen and tree dating suggests that the glacier had retreated approximately 500 m by 1938; this estimate is supported by an aerial photograph showing a proglacial lake just beginning to form in 1944. Recent glacier movements around the Hielo Patagonico Norte are discussed and it is concluded that the general trend of glacier retreat around the icefield, beginning in the 1860s to 1870s, is consistent with Northern Hemisphere trends.

Image analysis software was used to obtain various measures of thalli in crustose lichen communities. Lichens growing on flat-faced quartzite boulders in two glacier forefields were photographed an...

Dendrochronology, lichenometry, and analysis of aerial photographs taken in 1944, 1979, and 1983 were used to date the 19th- and 20th-century fluctuations of the Arco, Colonia, and Arenales glacier...

Boulder-surface dating techniques have been applied in many mountain and high-latitude environments, but have not yet been explored in the southern African region. This paper reports on the results of a pilot study to provide relative ages for openwork debris flow deposits in a part of the Cederberg mountains. Field techniques used included rock surface hardness assessment using a Schmidt hammer, lichenometry, and the determination of weathering rind thickness and weathering pit diameters. Within the eleven deposits investigated two age populations are successfully identified. Despite inherent weaknesses, analysis of the results show that the Schmidt hammer, weathering rind thickness and total percentage lichen give statistically significant results. Although the Schmidt hammer technique appears most objective on its own, it is the combined assessment of the various techniques that provides the most reliable results.

A soil chronosequence is presented based upon podzols developed on Holocene moraine crests in the Jardalen cirque complex, western Norway. Simple and inexpensive field and laboratory tests provide information on soil depth development, pH changes, silt/clay translocation and B-horizon reddening and thickness with age. Chronological control on historical moraine ages is provided by lichenometric dates, which support a 5 cm/100 year soil development rate for the first 700 years of pedogenesis. This initial rapid depth development tails off to a maximum rate of 0.06 cm/100 years between c. 1.5 ka and 10 ka BP based upon a Preboreal/Younger Dryas age for the oldest moraines and associated soils in the Jardalen cirque.

This article examines how snow plays a role in current erosive processes in a high mountain area (1800-2400 m a.s.l.) known as Penalara, located in Spain's Central Range (40° 50' N; 3° 58' W). The hypothesis maintains that snow becomes an important erosive factor when it accumulates over sedimentary or weathered materials, therefore geomorphological heritage is a key factor in nival erosion. To test this hypothesis, the authors identified the landforms in the study area and determined their relative ages by weathering and lichenometry (Rizocarpon geographicum ag.), differentiating between preglacial, glacial (Recent Pleistocene) and postglacial (Holocene) forms. The information was used to plot a reticulate pattern of observation sites for the study area. Snow depth and the movement of selected blocks at each site were recorded from October 1991 to June 1995. The relationship between late-lying snowpatches. geomorphological heritage and current erosive processes was determined. Between 1800 and 2000 m a.s.l., there is an indirect relationship between snowpatches and predominant processes (stream incision and gelifluction) on terminal moraines. Between 2000 and 2200 m, direct action is present where there are late-laying snowpatches on lateral moraines and some glacial steps. Between 2200 and 2400 m, gelifraction and gravity processes are also in direct relation to snowpatches.

A long-term approach based on detailed mapping and lichenometry provides additional information concerning talus-foot rock glaciers overstepping raised beaches in Svalbard. Their regional distribut...

A bibliography of New Zealand lichenology is presented comprising 260 entries, the majority spanning the period 1984–92. Subjects treated in the bibliography include: bibliography, chemistry, ecology, distribution, history and biography, lichenometry, physiology, and taxonomy.

Investigations of plant colonization patterns and lichenometry have provided new insights regarding past and present slope processes on Svalbard. Major stages in slope evolution during the Holocene have been identified, and the Neoglacial period (3500–2000 B.P.) is suggested as the starting point for the formation of lobate rock glaciers. Estimates of the frequency of episodic meteorological events, which have geo‐morphological implications, indicate a recurrence interval of rainstorm‐triggered debris flows and slush avalanches of 70 to 600 years. Active and stable slope deposits have been distinguished and the importance of runoff during spring melt and subsurface percolation later in the summer is implied. In order to interpret the data it is necessary to take into account lithology and to realize that some plant communities provide better indications than others. In contrast with the great variability of phanerogamic and moss communities, which primarily reflect ecological conditions, the stab...

The past decade has seen the development and application of over a dozen new methods for quantitative age-determinations of geomorphic surfaces. Some surface exposure dating methods are numerical, including the accumulation of cosmogenic radionuclides 10Be, 14C, 26Al, 36Cl, and 41Ca, accumulation of cosmogenic stable nuclides 3He and 21Ne, 14C dating of organic matter encapsulated in rock coatings, and dendrogeomorphology. Calendar ages are obtained by dendrogeomorphological analysis. Calibrated ages can be obtained by analysis of rock-varnish chemistry, lichenometry, weathering, and soils. Various methods can be used in combination to overcome individual limitations. Whereas conventional methods provide age control on stratigraphic profiles, surface-exposure dating methods are especially suitable for geographic problems, such as analyzing not only temporal, but also spatial variations in the rates of geomorphic processes. [Key words: geomorphology, process, geochronology, cosmogenic nuclides, Quaternary,...

The chronology for the younger Marquee and Arrowsmith moraine sets of the Cameron Glacier is revised. This is done by using new lichen growth curves for Rhizocarpon geographicum and R. candidum, developed for moraines of the Mueller Glacier at Mount Cook and calibrated with ages determined from rock weathering rind thicknesses. A new rock weathering rind curve was established for this purpose. The new lichenometric dates (greatest age estimated by either lichen, years B.P.) for the Cameron Glacier moraines are: Arrowsmith set: A1 c.170|A2 c.410|A2b c.480|A3 c.1010;A4 c. 1480|A5 c. 1960|Younger Marquee set: B1 c. 2320|B2 c. 3080|B3 c. 4480|B4 c. 5390. The kinds of vegetation and soils on the morainic time series are briefly indicated.

Geomorphic features as indicators of climatic fluctuations in a periglacial environment, northern Sweden

Communal game drives were a cost-effective way for pedestrian hunters to obtain large amounts of meat and hides. Although once common across North America, nearly all traces of game drives have been removed by modem agriculture practices. Thus, the two high-altitude sites in Colorado reported on in this volume are significant because their features are largely intact and their occupations can be reliably dated. Chapter 1 is a thorough overview of ethnohistoric game drives and hunting practices across North America. Chapter 2 focuses on the Trail Ridge Game Drive site located at the forest-tundra ecotone at 3,4653,500 m asl. Natural topography and constructed stone walls were employed to funnel herds to hunters waiting in blinds. Pellet-group studies suggest that the intended prey were elk or mule deer. Projectile points indicate intermittent occupation between the late Paleoindian and late prehistoric periods. Charcoal from two blinds was radiocarbon dated to 4590 ? 60 B.P. (Beta-85363) and 2610 ? 60 B.P. (Beta-75998), while granite weathering dates indicate that the walls were built or repaired numerous times. Chapter 3 discusses the extensive Flattop Mountain Game Drive site situated at 33503720 m asl. Features include 14 stone drive walls, 848 cairns, 90 blinds, and a possible hunter's bed. Numerous projectile points ranging from Paleoindian through protohistoric styles have been recovered in this vicinity since the 1920s, and these, as well as all other lithic tools, pottery and debitage, were analyzed. Fifteen radiocarbon samples collected within blinds date between ca. 4300 and 200 B.P. Chapter 4 places the two sites within a continental perspective. Both were used intermittently beginning in the Paleoindian period, and their features were maintained by various parties up to the protohistoric period. The appendixes address lichenometry, granite weathering, radiocarbon dating, pellet-group surveys, early artiay be disap ointed howev r, at the inco lusive i g. They may also be frustrated, as I was, by its a tic and repeti ve style and its limited and idiosynic selection among rel vant sources. fact collections, and descriptive data for all projectile points. This report is well organized and the numerous photographs, drawings, and graphs make it a valuable addition to the library of anyone interested in hunter-gatherer ecology in North America.

Two moraine sequences in one of the ice-free cirques in Topolovaya valley located above the cirque threshold at altitudes of about 700–800 m are dated by tephrochronology and lichenometry. Prominen...