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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...

A Schmidt Hammer was employed in evaluating the surface hardness of rocks which line ancient anthropogenic pit features, known as Pukaskwa pits, on the north shore of Lake Superior, Canada. This technique offers a possible new method of producing relative ana absolute dates for such exposed stone features Analysis of the data has provided a relative chronology for the pit features, representing two distinct construction phases. The range of absolute dates generated from the data indicates that the pits were likely constructed by Blackduck peoples c. 900 to 400 years BP.

We present a late-Holocene glacial and environmental history of three valleys within Miki and I.C. Jacobsen Fjords, East Greenland (68°N). The fjords have no direct connection with the main ice sheet and are presently glacierized by a series of local ice caps and glaciers. Little sediment has been deposited within the study area, but bedrock is distinctly glacially striated, which suggests that extensive valley glaciers reached the present coastline in the past. Moraines are the prominent morphological features including distinct end and lateral moraines. Most of the moraines are related to the existing glaciers in the area. Apparent moraines extend as far as 2 to 2.5 km in front of present-day glaciers. Based on morphological and stratigraphical studies of the sediments in these valleys, five glacier advances during the late Holocene are implied. Stabilization of the oldest moraines is lichenometrically dated to c. 1450 to 1650 years ago. Younger moraines in both Miki and I.C. Jacobsen Fjords are lichenometrically dated to c. 1050–1100 years ago, c. 750–950 years ago and c. 600–700 years ago. The youngest moraines containing measurable lichens stabilized c. 300–400 years ago. The timing of this moraine formation correlates to marine records from previous research on the inner part of Miki Fjord, where apparent intensification in sediment stratification is related to a glacier advance into the fjord c. 290 years ago. This glacial advance may correlate to the‘Little Ice Age’ cooling observed in many records from the North Atlantic region. Our glacial record from Miki and I.C. Jacobsen Fjords also shows good correlation with temperature proxies within the GRIP ice core in Greenland and foraminifera records from Nansen Fjord, East Greenland. Less pronounced correlation is observed with the Icelandic Sea Ice Index and records of glacier fluctuation in Iceland during the last .1000 years. These results suggest that widespread climatic cooling was the direct cause of many of the late-Holocene glacier variations documented in this study, although the glacial advance at c. 1050–1100 years ago coincides with the so-called‘Medieval Warm Period’, and could reflect the response of glaciers to increased precipitation within the area.

Establishing landslide chronologies is essential both for understanding causes of mass movements as part of fundamental geomorphological research, and for the assessment of landslide hazards as part of applied geomorphology. We discuss the applicability of different methods for determining landslide chronologies, frequencies and dynamics in relation to the type of material being dated, sampling location and type of mass movement. The emphasis is on the possibilities and limitations of the different dating methods. Established methods such as radiocarbon dating, lichenometry and dendrochronology are briefly discussed. The paper focuses, however, on (1) new analytical techniques like Accelerator Mass Spectrometry (AMS), Thermally Ionising Mass Spectrometry (TIMS) and laser fusion, which have led to significant improvements of established dating methods and on (2) new dating methods like Optically-Stimulated-Luminescence (OSL) dating and Alpha-Recoil-Track (ART) dating.

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.

Holocene glacial deposits in Sredniya Avacha headwaters are subdivided into three age groups (events A, B, and C) based upon geomorphic features, tephrochronology, and lichenometry. Tephras of Opala volcano (1400–1500 yr B.P.), Ksudach volcano (1700–1800 and 6000 yr B.P.), and Zavaritskiy volcano (2800 yr B.P.) are used as stratigraphic markers. Rhizocarpon geographicum (L.) DC and Rhizocarpon section Alpicola growth curves are established using tephrochronologically dated and historical surfaces. The age of event A (pre-Hypsitermal?) moraines is constrained by an age of 6000 yr B.P. for overlying Ksudach-2 tephra and an age of 7200 (?) lichenometric (L) yr B.P. Event B (Neoglaciation) had a multiple nature, with the most prominent advances at 4300–3500, 3300–2800, 2600–2100, 1800–1400, and 1300–1100 (L) yr B.P.; the culmination occurred before 2800 yr B.P., as suggested by a date for Zavaritskiy volcano tephra found on the glacial and outwash deposits. Less-extensive glacier advances of event C (“Little Ice Age”), occurred at 800–600, 500–200, 180–110, and 90–40 (L) yr B.P. The ELA depression was 200–250, 100–150, 30–70 m during the culmination of events A, B, and C, respectively.

The study area is located on the northern face of Pico de Orizaba (Mexico, 5700 m ASL), on the terminal moraine of Jamapa Glacier, which dates from the Little Ice Age. Large debris flows are recurrent on the proglacial ramp. The comparison of lichen colonies growing on the deposits of the flows reveals that two generations of flows are present: an old one and a very recent one that occurred between 1994 and 1995. Studies were made of the sedimentologic characteristics of the flows and ground temperatures were recorded to a depth of 70 cm on the floor of the channels. Comparison of the lichen-growth on the exposed surfaces of the deposits led to the relative dating of the older debris flow, which is associated with the beginning of the retreat of the glacier and the saturation of the terminal moraine deposits by meltwater. The more recent flow has less transport capacity and is identified with the formation of an impermeable layer of permafrost that covers the bottom of the channel of the old debris flow. The permafrost layer formed when snow accumulations on the bottom of the channel were covered by ash that fell from the slopes.

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.

Summary Aim Develop a biologically defensible conceptual model to explain lichen population dynamics. Methods This work critically examines the biological basis for several of the key assumptions that are used to interpret lichen-size age data. It then presents a biologically defensible conceptual model that can be used to develop computer based simulations of lichen population dynamics or to design alternative approaches to lichenometry. Main conclusions Most lichenometric ages are not verifiably accurate and are generated by methodologies that do not incorporate widely accepted biological principles. Polymodality in thallus-size distributions is not always the product of discrete events. Polymodality could reflect continuous changes in the availability of inhabitable patches (gaps) in a heterogenous mosaic. Improvement in lichenometry could be realized by investigations that seek to quantify the temporal and perhaps density-dependent onset of departures from statistical normality for certain lichen cohorts or species groupings. The study of lichen communities on substrates of known age may, in the short term provide some indication of the relative timing of age-stage changes in lichen demographic structure.

The terminology of the genus Rhizocarpon, as used by lichenometrists, is at present confused and vague. The failure to differentiate even to the section level has resulted in errors in dating and has made the comparison of growth rates derived for different parts of the world difficult, if not impossible. The use of a standard nomenclature would clarify the degree of species differentiation that has been attempted in any given study.

Synchronous regional rockfall events triggered by large earthquakes in the Southern Alps of New Zealand were used to evaluate and improve the lichenometry method for surface-exposure dating. Digital calipers were used to measure the maximum diameter of the largest lichen on many rockfall blocks, using a fixed-area largest-lichen (FALL) sampling strategy. Regional significance of FALL peaks can be tested by confirming the occurrence of a coeval peak at multiple sites, and by showing an increase in peak size toward the earthquake epicenter. Significance of FALL peaks at a local site can be described in terms of peak size relative to a uniform density of FALL sizes. Measurements of 34 000 FALL sizes on fully exposed rockfall blocks and outcrop joint faces at 90 sites allow precise dating of geomorphic events of the past 300 to 500 yr. Uncertainties at the 95% confidence interval can be reduced to a level better than ±10 yr for ages within the calibrated time range represented by the lichen growth equation. Recognition of prehistorical regional rockfall events in 1833, 1836, and 1840 demonstrates the excellent resolution of this dating method. Precise dates result from exceptionally low measurement errors of lichen sizes relative to their growth rate, tightly clustered FALL sizes for earthquake-induced rockfall events, and substrate exposure times for calibration sites that are known to the year or day. FALL peaks for synchronous rockfall events are the same for 20 sites with diverse climate, altitude, and substrate lithology. A regionally consistent lichen growth rate allows use of a single growth-rate equation for most species of Rhizocarpon subgenus Rhizocarpon on the South Island of New Zealand. A nonlinear growth equation suggests that the first colonization, on average, occurs in the 5th yr after formation of new rock surfaces (~0.5 m 2 unit areas) and is followed by rapid, exponentially declining growth for about 20 yr (greatgrowth phase) that is largely completed by the 24th yr. Then, linear growth persists at about 15 mm per century (uniform-growth phase).

Widespread clastic deposits, 80n1800 m long, on the eastern side of the Sawtooth Range are the result of debris flow and slushflow. Small hillslope debris flows (10n10 3 m 3 ), originating on talus slopes at the mountain front and not associated with preexisting gullies, and large channelized debris flows (10 3 n10 4 m 3 ), debouching from basins within the mountains, are comparable morphologically to those in other high-latitude and high-altitude environments. Channelized deposits are often modified by the effects of slushflow and fluvial activity. Provisional lichen growth curves for the area were produced by correlation of thallus size with the enlargement of ice-wedge polygon troughs. Lichenometry and aerial photograph interpretation were used to estimate the age of deposits so that event frequencies and rates of geomorphic work could be calculated. Vertical transport by rapid mass movements during the 20th Century averaged 17 × 10 3 Mg·m·a n1 ·km n2 (± half an order of magnitude), corresponding to a rock denudation rate of 0.05 mm·a n1 for the basins and peaks feeding the east-facing slopes. Channelized debris flow produced more than 70% of this transport. Several of these large flows occurred in each of the three periods of 30n35 years examined, so their recurrence intervals are substantially shorter than values reported from locations in northern Scandinavia and Spitzbergen. Resume : Les dOpUts clastiques largement rOpandus, 80 ‡ 1800 m de longueur, sur le versant oriental du chaOnon Sawtooth, sont le rOsultat diOvnements de coulOes de dObris et de coulOes de bouillie neigeuse. De petites coulOes de dObris sur le versant (10n10 3 m 3 ), engendrOes sur les pentes de talus au front des montagnes et sans Œtre associOes ‡ des ravins prOexistants, et de volumineuses coulOes de dObris chenalisOes (10 3 n10 4 m 3 ) qui ont OtO OvacuOes des bassins localisOs ‡ liintOrieur des montagnes, sont morphologiquement comparables ‡ celles formOes en milieux de haute latitude et haute altitude. Les dOpUts chenalisOs sont frOquemment modifiOs par les effets crOOs par les coulOes de bouillie neigeuse et par liactivitO fluviale. Les courbes provisionnelles de croissance des lichens pour la rOgion ont OtO OlaborOes sur la base diune corrOlation de la dimension du thalle avec liOlargissement des fentes de polygones formOes par les coins de glace. La lichOnomOtrie et liinterprOtation de photos aOriennes ont OtO utilisOes pour Ovaluer li‚ge des dOpUts, et ainsi il a OtO possible de calculer les

This study employs sedimentological indices and lichenometric dating on the lichen species Plac opsis patagonica to investigate the nature and age of debris cones which have accumulated at the margins of the downwasting San Rafael Glacier in Chilean Patagonia. These cones appear to have accumulated by the resedimentation of glacigenic deposits by debris flows, with debris movement starting in the early 1980s. Cone activity follows a pattern of intense initial activity and sediment mobilisation followed by increased stability and colonization by vegetation. Three of the four cones had stabilized within 15 years of sediment movement initiation. These features may be seen as being conditioned by glacial activity with second order controls provided by the local climate and sediment supply. The cones have accumulated in a 'paraglacial' environment.

Habitats occupied by the largest Xanthoria elegans (Link) Th. Fr. thalli at seven glacier forefields in the Canadian Rockies were studied to investigate the lichenometric assumption that large thalli occupy ideal sites for growth. The largest thalli were found on steep or overhanging facets at the base of grey limestone clasts that were embedded in moraines. These thalli were unfragmented, had nearly circular outlines, were bordered by barren rock and had SSE to S orientations. This is consistent with the general expectation that south-facing sites offer high solar input and a long snow-free season. Orientations other than south could result by chance or may reflect the importance of microscale factors (e.g. reflected rather than direct solar input). Closure of X. elegans communities and coalescence of thalli was only found at sites that were naturally fertilized with dung. It is concluded that all clasts do not afford homogeneous or ideal environments for lichen growth and do not have an equal chance of being colonized. This raises doubts concerning the validity of statistical normality assumptions in lichenometry and the use of grids to assess closure in lichen communities.

Volumetric calculations of slope deposits, direct measurements of rockwall retreat and chronological control based on lichenometry provide a wide range of rockwall retreat rates in Svalbard (0–1580 mm ka−1) that appears consistent with previous evaluations from other Arctic areas. In northwest and central Spitsbergen (79°N), a triple-rate rockwall retreat is suggested for the last two millennia: very slow biogenic flaking (2 mm ka−1), moderate retreat due to frost shattering (100 ka−1) and rapid retreat associated with post-glacial stress relaxation (c. 1000 mm ka−1). Examination of the distribution of various processes indicates that the Holocene retreat of most rockwalls has not exceeded one or two metres. Bedrock conditions appear to be the main control on retreat rates. The massiveness of igneous and metamorphic outcrops, widespread in Arctic shield areas, largely accounts for the slowness of rockwall retreat, which on these lithologies is primarily due to chemical and biological processes. More rapid rates are usually associated with stress relaxation following glacial surges or with local frost susceptibility of bedrock, often where faulting has induced high joint density. At such sites, rockwall retreat rates are of the same order of magnitude as those reported from Alpine areas (1000–3000 mm ka−1) where both bedrock weakening due to tectonic stresses and the greater height of steep rockwalls account for the more rapid rockwall retreat rate. © 1997 by John Wiley & Sons, Ltd.

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.

Further evidence for an early 'Little Ice Age' in the Sandane area, southern Norway, is presented in support of the lichen data of Evans et al. (1994) and in response to the reassessment of Matthews et al. (1996). The geomorphological evidence for three phases of moraine deposition is clarified and relative age dating based upon Schmidt hammer R-values and soil development is presented. These data, in combination with the lichenometry reported earlier, indicate that the moraines of the Jardalen/Fagerdalen cirque in particular are not all of the same age (pre 'Little Ice Age' as suggested by Matthews et al. (1996) but instead date either to post-Preboreal/Younger Dryas times (Stage 1 moraines) or to the 'Little Ice Age' (Stage 2 and 3 moraines). The gradual increase in lichen diameters, R-values and soil depths from the youngest 'Little Ice Age' (Stage 3) moraine to the outermost and oldest Stage 2 moraine lends further support to the suggestion that the 'Little Ice Age' in western Nor way may have begun much earlier than previously documented in the literature. Problems in using the Schmidt hammer for relative age dating in mountainous terrain, where the moraines being dated are often con structed from old glacial deposits and fresh rock fall debris, are also dis cussed.

In this study we present preliminary results on the use of the lichenometric method for age estimation of moraine formation in the Mount San Lorenzo area (47°30' S, 72°21' W), southern Chile. We estimated lichen growth rates of individuals of genus Rhizocarpon, section Rhizocarpon, at two glacier-proximal sites for which independent age estimates were available. These two sites, Lake Shore and Moraine A, presented lichen mean annual growth rates of 0.33 mm and 0.15 mm, respectively. We applied these growth rates to two sites lacking previous dating control: Bedrock and Moraine B, and obtained minimum ages of 70 and 473 years, respectively. Our results allow us to confirm that there is a quantifiable relationship between Rhizocarpon size and age of the substrates in this environment. Based on this result we develop age estimates for sites of unknown age in Mount San Lorenzo. We discuss the factors that possibly determine the variability in the growth of Rhizocarpon in our study sites and compared them with those described in the literature. Este trabajo presenta resultados preliminares del uso de la liquenometría indirecta en el fechado de morrenas en el Monte San Lorenzo (47°30' S, 72°21' W), sur de Chile. A partir de la determinación de las tasas de crecimiento de líquenes del género Rhizocarpon, sección Rhizocarpon, en dos sitios datados previamente (Costa de Lago, con una tasa de crecimiento de 0.33 mm por año, y Morrena A, con una tasa de 0.15 mm por año) se aplicaron estas tasas en dos sitios sin datar, Roca Basal y Morrena B, obteniendo edades mínimas de 70 y 473 años, respectivamente. Nuestros resultados nos permiten afirmar que existe una relación cuantificable entre el tamaño de los líquenes y la antigüedad de los sustratos, a partir de la que fue posible estimar edades mínimas para los sitios de edad desconocida. Se discuten los posibles factores que estarían determinando la variabilidad en el crecimiento de Rhizocarpon en nuestros sitios de estudio y se comparan estos con los descritos en la literatura.

In this study we present preliminary results on the use of the lichenometric method for age estimation of moraine formation in the Mount San Lorenzo area (47°30' S, 72°21' W), southern Chile. We estimated lichen growth rates of individuals of genus Rhizocarpon, section Rhizocarpon, at two glacier-proximal sites for which independent age estimates were available. These two sites, Lake Shore and Moraine A, presented lichen mean annual growth rates of 0.33 mm and 0.15 mm, respectively. We applied these growth rates to two sites lacking previous dating control: Bedrock and Moraine B, and obtained minimum ages of 70 and 473 years, respectively. Our results allow us to confirm that there is a quantifiable relationship between Rhizocarpon size and age of the substrates in this environment. Based on this result we develop age estimates for sites of unknown age in Mount San Lorenzo. We discuss the factors that possibly determine the variability in the growth of Rhizocarpon in our study sites and compared them with those described in the literature.

Neoglaciation is the climatic episode characterized by rebirth and/or growth of glaciers following maximum shrinkage during the Hypsithermal interval. A large database of Neoglacial glacier variations in the North and South American cordilleras makes an assessment of the chronology and general pattern of these variations possible. Early Neoglacial moraines are common in southernmost South America, where they are the most extensive. In North America, Early Neoglacial deposits are rarely encountered and are typically buried beneath younger deposits. Middle Neoglacial moraines are common on both continents; in South America, they are more extensive than those of the Little Ice Age, but in North America they are typically equal or nearly equal in extent. In the Cascades, Olympics, and Rocky Mountains, Little Ice Age glacier advances of the seventeenth to the nineteenth centuries were generally the most extensive of postglacial time. In southcoastal Alaska, calving tidewater glacier termini tend to fluctuate nonsynchronously, although they are broadly synchronous on a millennial timescale. Insolation appears to have played a primary role in controlling the relative extent of Neoglacial advances in each hemisphere, implying that summer temperature was a dominant factor in glacier mass balance.

In many environments, landslides preserved in the geologic record can be analyzed to determine the likelihood of seismic triggering. If evidence indicates that a seismic origin is likely for a landslide or group of landslides, and if the landslides can be dated, then a paleo-earthquake can be inferred, and some of its characteristics can be estimated. Such paleoseismic landslide studies thus can help reconstruct the seismic history of a site or region. In regions that contain multiple seismic sources and in regions where surface faulting is absent, paleoseismic ground-failure studies are valuable tools in hazard and risk studies that are more concerned with shaking hazards than with interpretation of the movement histories of individual faults. Paleoseismic landslide analysis involves three steps: (1) identifying a feature as a landslide, (2) dating the landslide, and (3) showing that the landslide was triggered by earthquake shaking. This paper addresses each of these steps and discusses methods for interpreting the results of such studies by reviewing the current state of knowledge of paleoseismic landslide analysis.

Randomisation tests on boulder weathering data distinguish moraines of four different ages in the Rongbuk Valley, all deposited by valley glaciers flowing northward into Tibet from the Himalaya. Lichenometry utilising subgenus Rhizocarpon distinguishes two groups of moraines, those

Studies of synchronous prehistorical landslides in rugged plate boundary mountain ranges can be used to estimate times of earthquakes, to locate the earthquake-generating fault zones, and to describe patterns of seismic shaking. Lichenometry can date regional rockfall events caused by large earthquakes in the Southern Alps of New Zealand with a 95% confidence level precision of ≤10 years. Spatial variation of rockfall abundance (an index of seismic shaking) is a function of the intensity and duration of seismic shaking and hillslope sensitivity to earthquakes. Four of the earthquakes of the past 1000 years appear to have caused exceptionally widespread regional rockfall events that were largest opposite the 350-km-long Cook segment of the Alpine fault. Lichenometric age estimates (± 10 years) of these Cook segment earthquakes at 1748, 1489, 1226, and 967 A.D. are supported by radiocarbon and weathering rind age estimates of times of coseismic geomorphic processes and by times of prehistorical forest-disturbance events. A mean earthquake recurrence interval of 260 years ±15 years and similar patterns of seismic shaking imply constant rupture length and slip per event in accord with the characteristic earthquake model.

Lichenometric dating of moraines deposited by eight glaciers in the northeastern Brooks Range suggests major glacial advances or stillstands at about 2600, 1000, 450, and 60 lichenometric (L) years BP. The latter two advances of the early-middle and latest part of the 'Little Ice Age', respectively, formed promi nent moraines at all glaciers studied. In response to overall twentieth-century warming, these glaciers have retreated at average rates of 2 to 19 m yr-1 from the distinct ridges formed in AD 1890. Glacier thinning at rates of 0.7 to 0.9 m yr-1 accounts for over 90% of the ice loss.

Evidence for the timing and extent of late-Holocene glacial advances in the Tian Shan mountains, central Asia, is based on lichenometric and radiocarbon dating of end-moraines. Three phases of glacial advance occurred at 1700-2100 and 1100-1300 lichenometric (L) years ago, and then during the 'Little Ice Age', 150- 700 (L) years ago. Differences in the pattern of glacier variations between the northwestern frontal and inner areas of the Tian Shan are reflected in the equilibrium line altitude (ELA) depression of 23 glaciers studied at nine selected sites. The peripheral glaciers appear to have been significantly more extensive during late- Holocene advances than the glaciers of the inner areas. This difference seems to be explained by regional differences in humidification: in the northwestern periphery of the Tian Shan, the cold periods of the late Holocene were more humid than the warm period of the mid-Holocene; whereas, in the inner areas, the pattern of climate changes was the opposite (a warm and humid mid-Holocene was followed by a cold and arid late Holocene).

The periglacial landforms of the Central Tianshan are mainly distributed above the lower boundary (3200 m ASL) of permafrost. In the eastern part of the region, there are 130 days per year when the daily average air temperature fluctuates around 0°C. The annual precipitation is 430 mm. Thus, periglacial landform development reflects the high frost-thawing frequency. By contrast, in the western part, there are only 90 days per year when the daily average air temperature fluctuates around 0°C; thus, periglacial landforms are those typical of areas with low frost-thawing fequencies, even though the annual precipitation reaches 827 mm. Based on observations from 1985 to 1989, schist (bedrock) cracks have a maximal dilatational value of 19 mm/a in the region, and gneiss cracks have a maximal dilatational value of 4 mm/a. The frost-heaving of diorite reaches 8–40 mm/a. The moving rate of rockfall talus is 1 m/a. On sunny slopes (195°SW), the talus debris has amounted to as much as 31.5 cm in the past 25 years, but on semi-shady slopes (65°NE), the debris accumulation is only 5 cm. The alluvial talus (scree) has a downward movement rate of 146 cm/a on south-facing slopes, and 73 cm/a on north-facing slopes. Block slopes have a downward movement rate of 96 mm/a on sunny or semi-sunny slopes and 72 mm/a on the shady or semi-shady slopes; the average rate is 81 mm/a in the study region. East of 86°E, the lobate rock glacier is the main type and its mean moving rate is about 6 cm/a, as deduced by debris discharge which has covered the highway over the past 25 years. Measurements from 1985 to 1986 show that the movement of lobate rock glaciers is from 1 to 49 cm/a. Rates at the higher elevation (15.5–49 cm/a) are faster than at the lower elevation. At the same elevation, the rates on the northward slopes (about 49 cm/a) are greater than on southward slopes (45 cm/a). According to lichenometry data, lobate rock glaciers formed between 3949 a BP to 180 a BP. West of 86°E, the main rock glacier type is the tongue-shaped rock glacier. The mean movement rate is 0.4 m/a. Gelifluction lobes and terraces have an average annual movement of 25 cm in the east. In the west, the average annual movement rate of gelifluction is 49 cm/a.

Recent work by McCarroll (1993, 1994) suggests that a new approach to lichenometry can be used to date diachronous surfaces. Size–frequency distributions of largest lichens obtained from the diachronous surfaces of avalanche boulder ramparts comprise two elements: an equilibrium population growing on boulders deposited throughout the Holocene, and overlapping populations growing on groups of boulders deposited by events during the last 300 years. In this study, almost 10000 lichens were measured on two groups of closely similar ramparts. The number of very large lichens is used to predict the form of the equilibrium distribution, which is then removed, leaving a corrected distribution which reflects the age-frequency of surface boulders deposited during the ‘Little Ice Age’. The results confirm that maximum avalanche activity occurred during the 19th century, but a minor peak at one site suggests that avalanche activity was enhanced during the mid-18th century.

Lichenometry was used to date “Little Ice Age” moraines in the Kamchatka peninsula, northeastern Russia. The Rhizocarpon geographicum growth-rate curve was based on seven data points from lava flows and moraines, dated using historical records or tephrochronology (15–300 BP). No reduction in growth rate due to decreasing lichen age was observed, so a linear approximation was used. Accuracy test results yield differences between real and calculated dates up to, but not exceeding, five years. From eight “Little Ice Age” (LIA) moraines it was established that Kamchatka glaciers advanced in the 1690s, 1850–70 and 1910–20. Only one moraine clearly corresponded to the 1690s advance. The maximum stage of the LIA was during the mid- to late 19th century when glacier fronts were generally 100–200 m lower than at present. Glacier termini with ash and moraine layers, covered by lichens and vascular plants, have been preserved for 150–300 years, judging by the lichen sizes.

The particularity and biological diversity of lichens reflect in dual nature of lichens, lichen species, living environment, vitality, growth speed, secondary metabolites, are briefly discussed, and significance of lichens in studying symbiosis evolution, lichenometry, medicine and to monitor air pollution, is introduced in the present paper.

Alluvial fans and debris cones are important buffers in the sediment cascade from mountains to the sea. Interactions between tectonic, climate, and base-level controls often render fans and cones dynamic geomorphic features – even on timescales of millennia and beyond (Harvey 2010). Unraveling such dynamics has proven difficult mainly because establishing chronologies for fans and cones is challenging: Buried organic remains are usually scare (Chiverrell and Jakob 2012, this volume), dendrochronology and lichenometry (Schneuwly-Bollschweiler and Stoffel 2012, this volume; Jomelli 2012, this volume) will often be limited to cone and fan surfaces and help accessing the recent past only (Lang et al. 1999), and rarely are tephra layers preserved or synsedimentary carbonates developed that would permit radiometric dating. Luminescence dating can offer an alternative as it allows determining the time when sediments were laid down. But limitations exist that are related to (i) limited exposure of sediment grains to daylight during the short and rapid transport of many fan deposits and (ii) low luminescence sensitivity of quartz from many high mountain environments. After a brief introduction on luminescence dating techniques, an overview of relevant dating applications is given and the possibilities and limitations of applying luminescence dating to alluvial fan and debris cones are discussed.

Mountain glaciers are one of the most reliable climatic proxy on Earth through their rapid response to slight changes in forcing and their wide distribution. For these reasons glacial chronologies constitutes reference series against which other paleoenvironmental reconstructions are evaluated. In the current context of global warming and glacier withdrawal worldwide, the building of such records is increasingly needed to assess these rapid and dramatic changes on the longer Late Quaternary timescale. The Holocene glacier fluctuations are now fairly well known in the Central and Eastern Alps, but datas from the Western Alps are extremely sparse, and the chronology of glacier fluctuations before the second half of the Little Ice Age (LIA) ss (1570-1850 AD) is thus poorly constrained. To fill this gap, we carried out a study on several sites distributed in three glaciated range of the French Alps (Mont Blanc, Belledonne, Ecrins). We choose a multi-proxies approach based on the implementation of several dating methods (dendrochronology, Cosmic Ray Exposure dating with 10Be, lichenometry, radiocarbon) – some of which were used for the first time on these spatial- and time-scales. This approach allowed us to propose a glacial chronology spanning the Holocene. Moreover, strength and weakness of the different methods used are discussed, and the results are compared to other high resolution proxies from the Great Alpine Region. Our results shows a picture broadly similar to the Holocene glacier variations model currently accepted in the European Alps : we shows evidence for large Early-Holocene advances prior to 9.3 ka and for the beginning of the Neoglacial period from 4.2 ka onwards. An accurate dating of the Neoglacial stadials was possible at Mer de Glace through the use of a dendroglaciological approach on subfossil woods (Pinus cembra). This site already appears as one of the most interesting in the whole Alps to study the Neoglacial period, as the chronology established there spans the last 4 ka and is the 4th record of this kind builds in the Alps. The datings presented here reveals a marked synchroneity for Neoglacial maxima at the Alpine scale, which could indicate similar forcing on glaciers from the Western fringe. Main discrepancies between the records could be explained by topographic and size characteristics of the studied glaciers, as expressed by their response time., Les glaciers de montagne sont l'un des meilleurs indicateurs des changements climatiques du fait de leur réponse rapide à de faibles variations des paramètres de forçage et de leur large distribution sur la planète. Les chronologies glaciaires représentent de ce fait des enregistrements de référence parmi les reconstitutions paléo-environnementales. Dans le contexte actuel de réchauffement et de retrait glaciaire accéléré, le développement de telles chronologies est nécessaire afin de mettre en perspective ces changements rapides et de grande ampleur avec ceux du Quaternaire récent. Si les fluctuations glaciaires holocènes sont relativement bien contraintes dans les Alpes centrales et orientales, les données sont en revanche extrêmement fragmentaires dans les Alpes occidentales avant la seconde moitié du Petit Age Glaciaire ss (1570-1850 AD). Pour pallier ce manque, nous avons conduit une étude sur plusieurs sites répartis dans trois massifs des Alpes françaises (Mont Blanc, Belledonne, Ecrins), en mettant en œuvre une approche multi-proxies basée sur plusieurs méthodes de datation (dendrochronologie, datation cosmogéniques 10Be, lichénométrie, datations radiocarbone) – dont certaines utilisées pour la première fois à cette échelle spatiale et temporelle. Tandis que les potentialités de chacune de ces méthodes sont discutées, notre étude a permis de proposer une chronologie des variations glaciaires couvrant la période holocène, dont les résultats sont comparés à d'autres enregistrements paléoclimatiques régionaux à haute résolution. Les résultats révèlent un schéma des fluctuations glaciaires holocènes comparable à celui généralement admis dans le reste des Alpes, avec la mise en évidence de récurrences glaciaires importantes au début de l'Holocène, antérieures à 9.3 ka, et la datation du début de la période du Néoglaciaire dès 4.2 ka. Une contrainte précise des différents stades de la seconde moitié de l'Holocène a pu être obtenue sur le site de la Mer de Glace grâce à l'approche dendroglaciologique sur bois subfossiles (Pinus cembra). Ce site apparaît d'ores et déjà comme l'un des plus importants pour l'étude de cette période puisque la chronologie établie couvre les 4000 dernières années et représente le quatrième enregistrement de cette précision à être développé dans les Alpes. Les datations obtenues indiquent en outre un synchronisme marqué des maxima glaciaires à l'échelle régionale, ce qui suggère une similarité des forçages sur la frange occidentale des Alpes. Les différences observées avec les chronologies du reste de la chaine s'expliqueraient principalement par les caractéristiques des glaciers étudiés, en particulier leur temps de réponse différent.

A new approach to lichenometry, based on large samples of the single largest lichen on each boulder, is presented. On surfaces of uniform age, lichen sizes measured in this way are near normally distributed, so the mean value can be used in constructing lichenometric-dating curves. By combining mean values from several sites, statistically defined confidence limits can be assigned to predicted dates. In a pilot study, dates obtained for 'Little Ice Age' moraines of two glaciers in southern Norway are consistent with those obtained using other approaches. Unlike standard lichenometry, the new approach can be used to investigate the age-frequency of boulders on diachronous surfaces formed by continuous or periodic accretion or disturbance. It has been used successfully to access the record of late-Holocene snow avalanche activity retained on avalanche boulder ramparts in upper Jostedalen, western Norway. Pilot studies are also presented of its use on a talus slope, solifluction lobes and periglacial patterned ground. Although there are some problems and limitations to its use, in many circumstances these are likely to be outweighed by the advantages of the new approach over standard lichenometry.

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...

Moraine sequences, protalus ramparts, rock glaciers and various slope deposits in seven separate glacier basins provide lichenometric ages for glacier retreat in an upland area of Sogn-og- Fjordane, southern Norway. Geomorphological mapping, relative dating based on section Rhizocarpon size-frequency distributions, observations on vegetation cover, and numeric dating based on a regional lichen dating curve for section Rhizocarpon, place moraines into three groups: Stage 1 moraines of likely Preboreal or Younger Dryas age; Stage 2 moraines of pre- or early 'Little Ice Age' but post-Preboreal age (thirteenth-fourteenth centuries); and Stage 3 moraines of fifteenth-century age and younger. The occurrence of thirteenth-sixteenth century (pre- or early 'Little Ice Age') moraines at low altitudes in the Sandane area is thought to relate to greater availability of moisture and to the capture of wind- drifted snow. These moraines are some of the oldest 'Little Ice Age' moraines dated by lichenometry in southern Norway. In some cirques, glaciers retreated from their fifteenth-century positions allowing protalus rampart development, scree accumulation and debris-flow activity to continue until the present.

Multiple geochronologic techniques, when used in an integrated approach, provide a powerful means of deciphering the stratigraphy of Holocene moraine sequences. The Jarvis Creek Ash, deposited across central Alaska at 3650 ± 125 BP, underlies a mid-Holocene lateral moraine of the Gulkana Glacier. This tephrochronological datum provides new control on long-term Rhizocarpon geographicum growth rates in central Alaska, and suggests that this species grows at approximately 4mm per century in the central Alaska Range. Lichenometry, together with tephrochronology and radiocarbon dates from buried organic horizons, indicate Holocene advances of the Gulkana Glacier occurred c. 5700 ± 260 BP, 4100 ± 800 BP, 3600 ± 700 BP, 800 ± 125 BP and 150-200 years ago.

Studies of rockfalls and block slides provide insight about seismic shaking hazards in alpine mountains subject to earthquakes. Large samples of the longest axis of the largest lichen on each block can be used to identify regional landslide events; lichen-size distributions for many sites cluster consistenly at the same sizes. The coseismic rockfall lichenometry model can be used to (1) date and locate prehistorical earthquakes, (2) document regional frequency of earthquakes, and (3) describe regional patterns of seismic shaking. Determination of colonization time, great-growth phase, and especially uniform phase rates of lichen growth are essential for dating regional landslide events. Rocks that tumble downhill during historical earthquakes allow accurate calibration of the growth rate for Rhizocarpon subgenus Rhizocarpon ; these plentiful fresh substrates are dated to their day of formation. An initial calibration of uniform growth rate, based on historical and tree-ring dated landslides was fine tuned by assigning earthquake dates to mean values of lichen-size peaks for regional rockfall events that increase in abundance towards epicenters of historical earthquakes. Calibration for each new site is unnecessary in the Southern Alps of New Zealand and in the Sierra Nevada of California because several species of yellow rhizocarpons within each climatic region have constant growth rates that are independent of altitude or substrate lithology.

The object of this paper is to reconstruct the history of glaciation and the dynamics of mudflow activity as part of the development of landscapes in the Aksay Valley, Kirgizsky Ridge, over the last 2000 years. Glacial, mudflow and slope deposits were dated by lichenometry and the radiocarbon method. The results of 14C dating of buried soils shows that at about 1700 BP a period of activization of slope processes took place in the valley. The zone of alpine meadow was situated at that time at an elevation of about 2750 m and glacier termini were situated at about 3100-3200 m. The oldest mudflow surface, which was investigated by lichenometry, dates from the same time. New equations for the rate of growth of the lichens Aspicilia tianshanica and Rhizocarpon geographicum use the oldest mudflow surface as a control point. Two periods of reduced mudflow activity are identified by lichenometry, i.e., 350-450 and 130-240 BP, and the latter is confirmed by 14C dating of peat-soil interlayers in a mudflow stratum with the specific activity of samples exceeding NBS standard. Thus, a new modification of the 14C-dating method is demonstrated. Lichenometry on moraines of the Aksay Glacier shows that advances of the glacier took place in the fourteenth and late- nineteenth centuries as well as at the beginning of this century. The depression of equilibrium-line altitude (ELA) for the fourteenth and nineteenth centuries was 150-170 m and 100-120 m, respectively.

It is hypothesised that the Medieval Warm Period was preceded and followed by periods of moraine deposition associated with glacier expansion. Improvements in the methodology of radiocarbon calibration make it possible to convert radiocarbon ages to calendar dates with greater precision than was previously possible. Dating of organic material closely associated with moraines in many montane regions has reached the point where it is possible to survey available information concerning the timing of the medieval warm period. The results suggest that it was a global event occurring between about 900 and 1250 A.D., possibly interrupted by a minor readvance of ice between about 1050 and 1150 A.D.

Lichenometry is a dating technique that has problems relating to questionable assumptions. The development of a size frequency approach, previously used in attempts to resolve some of the problems, is described and applied to the dating of four debris flows marginal to the San Rafael Glacier in Southern Chile. This study provides examples of the development's application, its problems and directions for further work. The size frequency approach, based on new assumptions, uses parameters derived from population size frequency distributions of the lichen species Placopsis patagonica to provide relative and absolute dating for rock surfaces. Changes in the shapes of distributions suggest the relative age of populations. Absolute dating is based on a curve (spanning a 24 year time period) derived from mean diameter size/age correlations. A stratified random sampling design permits the use of inferential statistics. Standard deviations and confidence intervals show error margins, the degree of relatedness between neighbouring populations, and populations that are anomalous. One-way analysis of variance is used to indicate where populations may safely be grouped. The size frequency approach appears to be particularly suitable for use on unstable debris flows where secondary movements are common. The approach also demonstrates that lichen growth and colonization are sensitive to aspect differences and other variations in microhabitat.

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.

International audience; In a commentary about the paper ‛Asynchronous Little Ice Age glacial maximum extent in southeast Iceland’ (Geomorphology 114 (2010) 253-260), M. Dąbski questioned the validity of the generalized extreme value method and the Bayesian approach in lichenometric dating of the outermost LIA Fláajökull moraines in SE Iceland. This paper responds to these criticisms by explaining the relevance of the method applied and the relevance of the dates obtained.

Over a historical timescale, landscapes have been strongly affected by fluctuations in climate and by the impact of human societies. This study examines the historical evolution of mid-altitude fluvial systems in the Western Alps and Cevennes (SE Massif Central) in the context of marked climate and anthropogenic change at the end of the Little Ice Age (late 19th century). This work contributes to the reconstruction of river paleodynamics by investigating the nature and chronology of geomorphological changes in upper river basins. In order to produce a detailed reconstruction of hydromorphological changes, we combined two approaches: the study of historical archives and the use of bioindicators (the dating of terraces using dendrochronology and of silt benches using lichenometry in order to reconstruct the evolution of the river channels). The 19th century is a particularly propitious period for the study of surface dynamics because archives have preserved a wealth of qualitative and quantitative data concerning rivers (economic statistics, meteorological and hydrological observations, illustrative documents, descriptions by contemporary observers). It is also a period for which reliable dating methods are available for detrital deposits in rivers. The period provides new information on how the transition between the Little Ice Age and current climate conditions affected the evolution of drainage basins and stream channels by highlighting a succession of phases in the erosive process (e.g., the preparatory role of the drought of 1830–1838 in the erosion crisis of 1855–1870) and refining the chronology of events (very early onset of riverbed incision). The results highlight the effect of climate (small hydroclimatic fluctuations), amplified by strong anthropization, on the rhythm of landscape change and on the relative stabilization of the landscape at the end of the 19th century. In addition, the synchronization of phenomena on the two sides of the Rhone Valley shows that these changes took place on a regional scale.

Este trabajo presenta y caracteriza dos concentraciones de pilas de rocas identificadas en la margen sudoeste de la cuenca superior del río Santa Cruz (Argentina), en la Estancia Bon Accord. La edad mínima de estas estructuras es estimada a partir de análisis liquenométricos. Se recopila información sobre la existencia de este tipo de estructuras en la región patagónica. Por último, se discuten algunas de las funciones hipotéticas de estas acumulaciones utilizando casos arqueológicos locales y de otras partes del mundo. Clusters of cairns located on the southwestern margin of the upper Santa Cruz river basin (Argentina), at Estancia Bon Accord are characterized in this paper. The minimum age of these structures is estimated by lichenometric analysis. Similar lithic features recorded in Patagonia are addressed and compared with those found at Bon Accord. Finally, several hypotheses about their function are evaluated using previous regional and worldwide research.

The role played by lichens in archaeological and monumental areas as biodeteriogenic agents is discussed. Methods now used in the qualitative and quantitative analysis of lichenic colonisation on stonework are considered, and their standardisation is proposed. Lichens not only play a role in degradation but are also used as indicators of environmental characteristics. Thus the function of lichens as biomonitors in the broadest sense is discussed. The authors propose a methodological record with different approaches (auto ecology, synecology, phytosociology) that could be applied to stonework, historical and archaeological areas with the aid of integrated methodologies (biological traps, lichenometry, biomonitoring).

Comparison of the equilibrium line altitudes (ELAS) for the present (1980s) and the maximum 'Little Ice Age' depression determined for glaciers in the Skíõadalur/Svarfaõardalur area of the Tröllaskagi peninsula, northern Iceland, shows a rise of c. 50 m over the last 100-150 years. Meteoro logical data suggest that over the same period the mean summer temperature at the equilibrium line changed by at least 2.0°C. Application of a model of the relationship between mean summer temperature and winter accumulation at the ELA for glaciers in southern Norway suggests that such a temperature change should have led to a movement of up to 300 m in the ELA. The discrepancy between the observed and expected results is accounted for by an almost two-fold increase in winter accumulation. The application of this model highlights the potential importance of interpreting changes in ELA in terms of both temperature and precipitation, and the results from northern Iceland demonstrate that in some areas accumulation changes can almost balance considerable changes in temperature. There is also potential through this method for hypothesizing atmospheric changes as explanations of the climatic changes interpreted.