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Rockfall represents one of the most destructive geomorphic processes for infrastructure and settlements located at the foot of mountain slopes. Furthermore, it poses a hazard for visitors and hikers. Despite the high anthropic activity in these environments, research on the reconstruction of rockfall in the high mountains of Mexico is still scarce. We used dendrochronological, dendrogeomorphological and lichenometric approaches to study the age and rockfall dynamics in a talus slope in central Mexico. Tree- ring chronologies were constructed from 140 samples of 50 Pinus hartwegii trees, 10 Juniperus monticola shrubs and 16 Ribes ciliatum shrubs to determine the age, frequency and rockfall stability at the upper limit of the forest (~4000 m a.s.l.). 52% of the tree samples showed impact scars, 39% callus tissue, 7% growth suppression and 2% corresponded to trees killed by rockfall. The frequency of rockfalls has increased since the second half of the 20th century, with the 1990s being the period of greatest activity. The years with the greatest disturbance were 1991, 1994 and 1998, possibly due to the intense rainfall that accumulated during the summer, as well as the earthquakes recorded in central and southern Mexico with magnitudes ⩾6. For the lichenometric analysis, 231 thalli of Rhizocarpon geographicum were measured in an active rockfall area. The results suggested three areas of rockfall activity. In the first area the ages were from 61 (±5 year) to 322 years (±41 year). In the second area, the ages were from 12 (±3 year) to 50 years (±12 year). The third area corresponds to an active zone with lichen-free blocks, located near the escarpment. The combination of dendrochronological and lichenometric methods allows a better determination of the minimum ages of rockfall, frequency, spatial distribution, and their possible factor triggers. [ABSTRACT FROM AUTHOR]

We present 11 10Be ages of the moraines of the Irik and Kashkatash glaciers that allowed identifying and dating several Late Holocene glacier advances for the first time, including a prominent advance exceeding the Little Ice Age (LIA) maximum that occurred at 1.6–1.7 ka at еру Irik Glacier. The advance is dated by the three very close 10Be ages of a moraine (1.57 ± 0.23 ka, 1.63 ± 0.23, and 1.68 ± 0.24 ka) located in the vicinity of the moraines of the Little Ice Age (LIA) maximum advance. The advance that occurred at 1.6–1.7 ka might be a possible analogue of the “Historical” stage described earlier in the Caucasus in literature basing at geomorphic evidence, speculations, and analogues with other mountain regions, but not dated. Another possibility is a potential correlation of this advance with the Late Antique Little Ice Age cooling in 536 to ~660 CE. The age of Irik Glacier advance is close to the humid period identified in the Garabashi (Baksan, Elbrus valley) lake sediments at 1500–1700 years BP. The magnitude of the identified glacier advances over the past two millennia was similar. Between the advance of 1.6–1.7 ka and the position of the glacier in 2022 CE the elevation of the Irik Glacier front increased by 520 m from 2490 to 3010 m asl. Four 10Be dates (0.7 + 0.11, 0.72 + 0.11, 0.77 + 0.11 and 0.82 + 0.18 ka) of the lateral moraine of the Kashkatash Glacier constrain the advance of the first stage of the LIA. The advance of the 13th century is also dated by 10Be at the DonguzOrun and Chalaati glaciers located at the Northern and Southern slopes of the Caucasus, respectively. The corresponding cooling in ca 1250–1400 CE is identified in the sedimentary paleoclimatic proxies of Lake Karakel (Teberda valley). A later advance at the Kashkatash Glacier is constrained by only one 10Be date (0.53 ± 0.13 ka) and needs further confirmation. Till deposited between the 1490s and 1640s at the Greater Azau Glacier is close to the date of this advance of the Kashkatash Glacier. A cooling at that time is recorded in the proxies of Karakel Lake sediments (1500–1630 CE). Three other 10Be dates of two earlier advances at 0.25 + 0.04 ka and between 0.14 + 0.03 and 0.16 ± 0.02 ka at Kashkatash Glacier are indirectly supported by tree-ring, lake sediment, 14C, and historical data. Further research and new data is necessary to increase the credibility and accuracy of the dates of glacier advances of the Late Holocene in the Northern Caucasus.

Widespread glacial retreat is now occurring in many arctic mountain ranges, yet little is known about primary succession following deglaciation in these settings. Newly created habitats could provide refugia for flora and fauna whose ranges are threatened elsewhere by rapid warming. To assess vegetation responses to glacial retreat in an arctic–alpine setting, we first describe plant community development on two recently deglaciated moraines in the Brooks Range. We then compare these recent communities with communities developed along a moraine chronosequence that spans >125,000 years and ranges in altitude between 800 and 1,700 m.a.s.l. Results show that (1) within twenty-two to thirty-six years following deglaciation, primary succession begins with the assembly of small communities of eight to thirteen vascular and nonvascular plant species; (2) species turnover is low, with many pioneer taxa, particularly lichens, persisting at the oldest sites and across all altitudes; and (3) overall, succession is directional and slow, with species richness increasing for up to 25,000 years, and percentage vegetation cover reaching >100 percent on the oldest glacial deposits. This is the first vegetation study on primary succession in the high central Brooks Range, and it supplies a previously missing alpine element within a vegetation transect across northern Alaska’s bioclimatic gradient.

Archaeologists keep a limited arsenal of methods for dating stone features at alpine sites. Radiocarbon (14C) dating is rarely possible, and it is common that dates do not accurately represent the activity of interest (stone feature construction). In this paper I review a legacy set of 89 14C dates for stone driveline sites built by hunter-gatherers in Colorado's Southern Rocky Mountains. I amend the sample of dates using chronometric hygiene and focus on dates with direct association to hunting features. I then present a newly calibrated set of 29 lichenometric dates for rock features at these sites and use hygiene protocols to remove inaccurate dates. Size-frequency lichenometry, though poorly known in archaeology, provides a way to date stone features indirectly by measuring the growth of long-lived lichens that colonize rock surfaces after construction events. Bayesian modeling of the combined set of dates suggests that the tradition of alpine game driving spans over 6000 years BP, with abundant use over the last 2000 years. Archaeologists must use multiple methods for dating stone features in alpine environments. This Bayesian analysis is a formal effort to combine lichenometry and 14C dating for archaeological interpretation. [ABSTRACT FROM AUTHOR]

Featured Application: The paper displays the analysis of lichen colonization of rocky fault-scarps to perform geochronological analyses and evidence ancient to historical earthquakes. This applied research shows the high sensitivity of vertical/horizontal position, geographical orientation and lithological nature of lichen colonized rock surfaces for the obtention of reliable lichen growth rates (LGR) applicable to geochronology. The Sencelles Fault constitutes the main extensional structure of Mallorca Island (Spain), holds a NE-SE orientation, and has been identified as the possible seismic source of the 1851 CE Palma earthquake (VII EMS.) The SE termination of the fault (Sta. Eugenia Segment) features a linear bedrock fault scarp of a maximum of 3.15 m height. The last 840 m of this rocky scarp display a significant horizontal banding, with up to five differentially weathered ribbons colonized by lichens. The lichenometric analysis is based on the measurement of 155 specimens of Aspicilia calcarea (Ac) and Aspicilia radiosa (Ar) in tombstones and funerary monuments (with inscribed dates) from the nearby cemeteries of Sta. María del Camí, Sta. Eugenia and Sencelles, to obtain the local lichen growth rates (LGR), with the two last graveyards being directly located in the fault zone. Lichens were measured on variously oriented (N, S, NE, SW, etc...) horizontal and vertical surfaces, generating differentially oriented lichen populations (DOLPs) to be compared with the Ac and Ar specimens colonizing the studied fault scarp (38 measured individual specimens). After successive trial and error regression tests, vertical DOLPs resulted in the best appropriate groups for the analysis, with LGR of 0.23–0.31 mm/yr. Horizontal ones reached widths of up to 20 cm, with LGR up to 0.84 mm/yr, which were clearly oversized. The application of the selected LGR points to a human-induced origin for the thin basal lichen ribbon of the scarp (10–13 cm), which should have developed during the middle 20th century (c. 1950–1966) because of documented ground leveling works. However, the second ribbon of the scarp (23–47 cm) shows exposure dates of 1852 ± 40 (Ar) and 1841 ± 59 (Ac), overlapping the date of the 1851 CE earthquake. The study is complemented with data from a fault trench excavated in the year 2002 at the toe of the scarp. The combined data of lichenometry, fault trenching, and the length of the analyzed fault scarp (c. 840 m) indicate that the studied segment of the fault cannot be considered a co-seismic surface faulting related to the 1851 CE event as a whole, but a relevant secondary earthquake effect on a pre-existing fault scarp (e.g., sympathetic ground ruptures). [ABSTRACT FROM AUTHOR]

Dendrochronology, and lichenometry were used to determine the relative and absolute age of the Late Holocene moraines of the glaciers of the Aktru, Maashei and Shavla valleys (North Chuya ridge, Central Altai). An array of 86dendrochronological dates, related to moraine deposits, is analyzed, 30 of which are published for the first time. Also, for the first time, data on the relative (lichenometric) age of the young deposits of the Aktru Valley, and data on the lichenometry of the moraines of the Maashey glacier and one of the glaciers of the Shavly valley were obtained. We used the capabilities of each method and the expediency of their combined use in the study area. It was confirmed that the growth rates of lichens on the moraines of the Aktru stage (XVIII–XIX centuries) are generally consistent with the previously published estimates. The moraines of the Historical stage, which date earlier than 1700–2300 years ago, supports the lichens as large as 120–160 mm, but the scattering of their diameters is too large and the assessment of the lichenometric ages of these moraines seems to be problematic, but not completely excluded. The Akkem stage of glacier advance according to the recent publications dates back to the Late Glacial or Early Holocene time; the lichenometry is obviously not applicably at such ancient surfaces. According to dendrochronological dating, the glaciers of the North Chuisky Ridge in the last millennium advanced at least twice up to their maximum extent in the XVII– early XIX and XII centuries. In the 8th century, the sizes of the glaciers possibly, approached modern ones. Aſter the XVII century, the cedar (Pinus Sibirica) in Central Altai significantly reduced its distribution area due to the climate cooling, retreating from the periglacial territories, where it was distributed earlier. All trees that grew near the glaciers, above 2300 m, died. The comparison of the dates of glacier advances in the past millennia with the tree-ring, ice-core, and palynological reconstructions of summer temperature and precipitation show a good correspondence.

Establishing a record of large debris flow events in high Alpine areas prior to the availability of high resolution remote sensing data can be very challenging. In this study, we investigate the debris flow activity in two tributary valleys of the Horlachtal catchment in Tyrol, Austria between the end of the Little Ice Age at about 1850 and the first available area wide aerial images from 1947. To accomplish this, we calculated a local lichenometric calibration curve using the long axis diameters of the five largest Rhizocarpon lichen thalli at 51 different reference locations. Because of the interval-censored dating of most of the reference sites, we established a bootstrapping approach within the calibration curve calculation process. With the help of the lichenometric calibration data, we were able to date 47 old debris flow deposits in the study area. The results indicate no increasing or decreasing trends in frequencies of extreme debris flow events. In addition, the results point to a very local character of debris flow triggering precipitation events, as we can detect major differences in neighbouring valleys. Lichenometric derived datings also provide temporal informations about the end of debris flow activity at some sites in the study area and thus can contribute to a better understanding of debris flow systems. [ABSTRACT FROM AUTHOR]

Lichenometry, a method for dating rock surface exposure mainly in high latitudes and mountain environments, is based on estimates of lichen growth rates, but over the last 70 years it has been severely criticised. Its chief limitation is its questionable reliability due to three main problems: the species belonging to the Rhizocarpon subgenus, most often used by lichenometrists, are hard to identify; growth studies have highlighted the intrinsic variability of growth both seasonally and annually, with species sensitively responding to a wide range of environmental factors; and the same sensitive dependence also applies to the time taken for colonization on fresh rock surfaces. These problems cast doubt on many absolute dating studies and critics have suggested that, at best, the technique should only be used for relative dating. This paper provides guidance on identification procedures and suggests alternative dating methods based on lichen size-frequency distributions and cross-dating with other lichen species, thus avoiding reliance on a single species or support from other methods. With appropriate development, it is hoped that these approaches can provide a way forward that allows the technique to contribute more reliably to the dating of rock surfaces in regions where there are few other dating options. [ABSTRACT FROM AUTHOR]

Widespread glacial retreat is now occurring in many arctic mountain ranges, yet little is known about primary succession following deglaciation in these settings. Newly created habitats could provide refugia for flora and fauna whose ranges are threatened elsewhere by rapid warming. To assess vegetation responses to glacial retreat in an arctic–alpine setting, we first describe plant community development on two recently deglaciated moraines in the Brooks Range. We then compare these recent communities with communities developed along a moraine chronosequence that spans >125,000 years and ranges in altitude between 800 and 1,700 m.a.s.l. Results show that (1) within twenty-two to thirty-six years following deglaciation, primary succession begins with the assembly of small communities of eight to thirteen vascular and nonvascular plant species; (2) species turnover is low, with many pioneer taxa, particularly lichens, persisting at the oldest sites and across all altitudes; and (3) overall, succession is directional and slow, with species richness increasing for up to 25,000 years, and percentage vegetation cover reaching >100 percent on the oldest glacial deposits. This is the first vegetation study on primary succession in the high central Brooks Range, and it supplies a previously missing alpine element within a vegetation transect across northern Alaska's bioclimatic gradient. [ABSTRACT FROM AUTHOR]

Spatio-temporal patterns of glacial retreat determine the intensity of geomorphological, hydrological, and ecological processes in the ice-free areas of the Antarctic Peninsula region. The chronology of glacial oscillations in the region following the Last Glacial Maximum (LGM) is still poorly constrained and mostly limited to data from a few sites adjacent to research stations. The Hurd Peninsula, located on Livingston Island (South Shetland Islands), is mainly covered by the Hurd Peninsula Ice Cap (HPIC); there is a ca. 20 km2 ice-free area downvalley of the ice cap in the peninsula's southern sector in addition to numerous nunataks that protrude above the HPIC. In this study, we present an approach combining two direct surface exposure dating methods, cosmic-ray exposure (CRE) dating and lichenometry, to reconstruct the spatio-temporal patterns of glacial thinning and ice cap retreat on the Hurd Peninsula. To understand the patterns of deglaciation on the peninsula, 26 samples for CRE dating (in situ cosmogenic 10Be) were taken from glacially polished surfaces and moraine boulders along a transect from the nunatak summits to the coast. On the most recent moraines, boulder stabilisation (i.e., indicative of glacier withdrawal) was dated through the longest axis of the 10 largest thalli of the lichen species Rhizocarpon geographicum. Ice thinning might have begun before the LGM at ca. 31.6 ka, when the highest areas close to the coast became exposed, and subsequently accelerated during the LGM at 20-18 ka. The upper surfaces were completely deglaciated between 16 and 14 ka. The HPIC was relatively stable until the mid-Holocene, when neoglacial advances of its outlet glaciers built moraines at ca. 4.5 ka. Subsequently, late Holocene polygenic moraines formed before the development of the external ridges of the most recent moraine system left by the HPIC outlets during the Little Ice Age, at 0.3 ka. The internal moraines correspond to glacial advances from the late 19th and early 20th centuries, as indicated by lichenometric dating. This work presents a comprehensive chronology of glacial oscillations on the Hurd Peninsula, enhancing our understanding of deglaciation patterns and offering insights into glacier dynamics due to climate variability and change. • We examine patterns of glacial thinning of an ice cap in the Antarctic Peninsula. • Thinning might have started before the LGM, and accelerated at ca. 18–20 ka. • Relative Holocene glacier stability resulted in minor neoglacial moraines. • Lichenometry dates recent glacial culminations at late 19th/early 20th centuries. [ABSTRACT FROM AUTHOR]

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The Sencelles Fault constitutes the main extensional structure of Mallorca Island (Spain), holds a NE-SE orientation, and has been identified as the possible seismic source of the 1851 CE Palma earthquake (VII EMS.) The SE termination of the fault (Sta. Eugenia Segment) features a linear bedrock fault scarp of a maximum of 3.15 m height. The last 840 m of this rocky scarp display a significant horizontal banding, with up to five differentially weathered ribbons colonized by lichens. The lichenometric analysis is based on the measurement of 155 specimens of Aspicilia calcarea (Ac) and Aspicilia radiosa (Ar) in tombstones and funerary monuments (with inscribed dates) from the nearby cemeteries of Sta. María del Camí, Sta. Eugenia and Sencelles, to obtain the local lichen growth rates (LGR), with the two last graveyards being directly located in the fault zone. Lichens were measured on variously oriented (N, S, NE, SW, etc…) horizontal and vertical surfaces, generating differentially oriented lichen populations (DOLPs) to be compared with the Ac and Ar specimens colonizing the studied fault scarp (38 measured individual specimens). After successive trial and error regression tests, vertical DOLPs resulted in the best appropriate groups for the analysis, with LGR of 0.23–0.31 mm/yr. Horizontal ones reached widths of up to 20 cm, with LGR up to 0.84 mm/yr, which were clearly oversized. The application of the selected LGR points to a human-induced origin for the thin basal lichen ribbon of the scarp (10–13 cm), which should have developed during the middle 20th century (c. 1950–1966) because of documented ground leveling works. However, the second ribbon of the scarp (23–47 cm) shows exposure dates of 1852 ± 40 (Ar) and 1841 ± 59 (Ac), overlapping the date of the 1851 CE earthquake. The study is complemented with data from a fault trench excavated in the year 2002 at the toe of the scarp. The combined data of lichenometry, fault trenching, and the length of the analyzed fault scarp (c. 840 m) indicate that the studied segment of the fault cannot be considered a co-seismic surface faulting related to the 1851 CE event as a whole, but a relevant secondary earthquake effect on a pre-existing fault scarp (e.g., sympathetic ground ruptures).

Glaciers are important indicators of climate change, and recent observations worldwide document increasing rates of mountain glacier recession. Here we present approximately 200 years of change in mountain glacier extent in northern Troms and western Finnmark, northern Norway. This was achieved through (1) mapping and lichenometric dating of major moraine systems within a subset of the main study area (the Rotsund Valley) and (2) mapping recent (post-1980s) changes in ice extent from remotely sensed data. Lichenometric dating reveals that the Little Ice Age (LIA) maximum occurred approximately 1814 (±41 years), which is before the early twentieth-century LIA maximum proposed on the nearby Lyngen Peninsula but younger than LIA maximum limits in southern and central Norway (mid-eighteenth century). Between LIA maximum and 1989, a small sample of measured glaciers (n = 15) shrank a total of 3.9 km2 (39 percent), and those that shrank by more than 50 percent are fronted by proglacial lakes. Between 1989 and 2018, the total area of glaciers within the study area (n = 219 in 1989) shrank by approximately 35 km2. Very small glaciers (

Lichenometry, a method for dating rock surface exposure mainly in high latitudes and mountain environments, is based on estimates of lichen growth rates, but over the last 70 years it has been severely criticised. Its chief limitation is its questionable reliability due to three main problems: the species belonging to the Rhizocarpon subgenus, most often used by lichenometrists, are hard to identify; growth studies have highlighted the intrinsic variability of growth both seasonally and annually, with species sensitively responding to a wide range of environmental factors; and the same sensitive dependence also applies to the time taken for colonization on fresh rock surfaces. These problems cast doubt on many absolute dating studies and critics have suggested that, at best, the technique should only be used for relative dating. This paper provides guidance on identification procedures and suggests alternative dating methods based on lichen size-frequency distributions and cross-dating with other lichen species, thus avoiding reliance on a single species or support from other methods. With appropriate development, it is hoped that these approaches can provide a way forward that allows the technique to contribute more reliably to the dating of rock surfaces in regions where there are few other dating options.

Flood frequency analyses relay on different source of data, including botanical records. Among these, the potential of dendrogeomorphology for flash flood reconstruction in torrential river systems has already been demonstrated in the specialized literature; however, studies combining other approximation techniques such as lichenometry are comparatively less abundant; and very few studies have questioned the advantages and disadvantages of applying these techniques in these particular fluvial environments. Here, we discuss the advantages and limitations of the use of Dendrogeomorphology and Lichenometry in the analysis of flash floods. We provide examples of application in different river systems that show how to overcome the disadvantages and provide complementary and even alternative information to classical sources. The methodological basis of the botanical data sources is based on the periodic environmental changes that condition the growth rate of living trees, manifested in sequence of tree-rings (i.e. studied by Dendrochronology) as well as the growth of several crustaceous lichens' species, manifested in the accumulated centripetal growth of the stems (studied by Lichenometry). These growth sequences can be used for relative and absolute dating of flood events by identifying growth disturbances related to this process. The results obtained are event dating and measurements of palaeo-stage, flooded area, residence time, depths, velocities and generating flows that can be used for the study of flash floods, allowing to improve the analysis of frequencies and the magnitudes of past floods. Yet, several challenges remain when using these approaches. The interannual variations of these environmental changes (sequences of dry or wet, cold or warm years, variations in insolation, plagues and epidemics, anthropic interference...) could limit the use of these sources for analysing flash floods, given that they require prior filtering processes of the climatic and environmental signal for the identification of disturbances, through the establishment of reference or pattern series, or the development of lichenometric growth curves. However, the advantages and contributions of these data sources and techniques far outweigh the methodological limitations, making them a promising field for the study of environmental changes in river systems. [ABSTRACT FROM AUTHOR]

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 the identification of the six episodes of glacier advances in the valley. Field-based geomorphologic evidence suggests that the glacial episode 1 (GEI) experienced the most extensive glaciation in the Hoksar valley extending ∼1 km down the valley (altitude 3565 m) from the current snout position of the Hoksar Glacier (altitude 3680m). Lichenometric dating of the moraines suggests that the GE1 episode is chronologically the oldest (∼480 ± 25 years) and GE6 episode the youngest (∼245 ± 10 years). The mean equilibrium line altitude (ELA) during the GE1 episode was calculated as 3755 ± 4 m compared to the observed present ELA position of 4060 ± 5 m, an upward shift of 305 m observed during the period. The spatio-temporal changes of the Hoksar Glacier during different episodes of the glacier advances until 2018 showed that the glacier area has shrunk from ∼212 ha during the GE1 to 100 ha at present losing an area of 112 ha (52%) during the period mainly as a result of the recent climate change. The recent observed glacier recession (1980–2018) is much higher (11 000 m2 a−1) compared to the past recession (1300 m2 a−1). The study provides valuable insights about the glacier recession in the Kashmir Himalayan region during the Late Holocene where knowledge about the past glacial history on a regional scale is generally poorly investigated. [ABSTRACT FROM AUTHOR]

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 tundra due to sample scarcity and poor context. I use a case study from a communal hunting site in the Rocky Mountains of North America to argue that archaeologists should use multiple dating methods to disentangle complex site formation histories. The High Grade (5BL148) game drive is located in Colorado's Southern Rocky Mountains and includes 30 stone walls, 52 hunting blind pits, and a short line of cairns. Dating results suggest occupations from 4650 b.c.–a.d. 1850, based on artifact typologies, radiocarbon dates on charcoal and bone collagen, and lichenometric dates on stone walls. [ABSTRACT FROM AUTHOR]

On the basis of dendrochronological, lichenometric and historical data with the use of Earth remote sensing materials, the evolution of the Donguz-Orun Glacier has been reconstructed over the past centuries. In this work we used aerial photographs of 1957, 1965, 1981, 1987, satellite image of 2009, as well as descriptions, photographs, maps and plans of the glacier of the 19th and 20th centuries, data of instrumental measurements of the glacier end position in the second half of the 20th – early 21st centuries, dendrochronological dating of pine on the front part of the valley, and juniper to date coastal moraines, and the results of lichenometry studies. It has been established that the Donguz-Orun Glacier in the past had several clearly marked advances about 100, 200 and more than 350 years ago, which are expressed in relief in the form of uneven-aged coastal moraines. Despite the fact that the Donguz-Orun Glacier differs from many mountain-valley glaciers of the Caucasus primarily by its predominantly avalanche feeding and a moraine cover, almost entirely covering its surface, the main periods of its advances are consistent with the known large fluctuations of mountain glaciers during the Little Ice Age in the early 20th, early 19th, and, probably, in the middle of the 17th century. However, unlike most other Caucasian glaciers, the Donguz-Orun Glacier advanced in the 1970s–2000s. Te scale of its degradation from the end of the 19th to the beginning of the 21st century is also uncharacteristic for the Caucasus: the reduction in the length for longer than a century period is only about 100 m.

On the Pico Cuiña cirque, Sierra de Ancares (León, Spain), the seasonal snow cover undergoes both slow and rapid mass displacements. Push associated with moving snow is responsible for an intense geomorphological activity, which is characterised by the plucking and transport of fragments of the bedrock, the abrasion of rock surfaces and the deposition of the mobilized material. Pronival ramparts are the most characteristic accumulation geoform created by pushing snow. Its study enabled us to verify the functionality of the nival processes and to prove the relative antiquity of some of them. The use of lichenometric techniques, based on the prior construction of a growth curve for lichens of the Rhizocarpon subgenus, has made possible to date sectors of the pronival ramparts. Lichenometric dates show a series of events of geomorphic activity of the snow cover fitting chronologically within the so-called Little Ice Age. It can be deduced from the observation of the current geomorphic dynamics of the snow cover that, although Little Ice Age temperature decrease might be important, particularly in the summer, the role of the variations in snow precipitation must be also taken into consideration.

In this study we tested whether young (Holocene) lava flows can be confidently dated based on the preservation of the primary geomorphological features, the stratigraphic position and historical records. To verify this hypothesis, we combined in situ-produced cosmogenic 36Cl exposure dating and lichenometry on two lava flows from the last eruptive cycle of Citlaltépetl (Pico de Orizaba), called Lava flow "A" and "B", previously attributed to 16th and 17th century eruptions, respectively. On lava flow "A", the measured in situ-produced 36Cl concentrations lead to a mean age of 3.03 ± 0.70 ka, while lichenometry yields a minimum age of ~1,130 years. Regarding lava flow "B", the measured in situ-produced 36Cl concentrations lead to a mean age of 1.45 ± 0.35 ka, whereas lichenometry gives a minimum age of ~1,000 years. The exposure ages derived from these methods indicate that both lava flows are significantly older than previously thought and therefore the combination of the preservation of the primary geomorphological features, the stratigraphic position and the historical records is not enough to determine their ages. Overall, the combination of in situ-produced 36Cl cosmic ray exposure dating and lichenometry, used for the first time in Mexico and supported by geomorphological, stratigraphic and historical record criteria, has a considerable potential for dating purposes and it could be useful to refine the eruptive history of other Mexican volcanoes. [ABSTRACT FROM AUTHOR]

Glaciers are important indicators of climate change, and recent observations worldwide document increasing rates of mountain glacier recession. Here we present approximately 200 years of change in mountain glacier extent in northern Troms and western Finnmark, northern Norway. This was achieved through (1) mapping and lichenometric dating of major moraine systems within a subset of the main study area (the Rotsund Valley) and (2) mapping recent (post-1980s) changes in ice extent from remotely sensed data. Lichenometric dating reveals that the Little Ice Age (LIA) maximum occurred approximately 1814 (±41 years), which is before the early twentieth-century LIA maximum proposed on the nearby Lyngen Peninsula but younger than LIA maximum limits in southern and central Norway (mid-eighteenth century). Between LIA maximum and 1989, a small sample of measured glaciers (n = 15) shrank a total of 3.9 km2 (39 percent), and those that shrank by more than 50 percent are fronted by proglacial lakes. Between 1989 and 2018, the total area of glaciers within the study area (n = 219 in 1989) shrank by approximately 35 km2. Very small glaciers (<0.5 km2) show the highest relative rates of shrinkage, and 90 percent of mapped glaciers within the study area were less than 0.5 km2 in 2018. [ABSTRACT FROM AUTHOR]

The aim of this article is to show the results of the lichenometrical and Schmidt hammer measurements performed in 2015 during the AMADEE-15 Mars Mission Simulation in the Ötztal Alps in order to test the capabilities of analogue astronauts and collect information on the geomorphic history of the study area since the Little Ice Age (LIA). The results obtained differ significantly from our expectations, which we attribute to differences in the field experience of participants and the astronauts’ technical limitations in terms of mobility. However, the experiments proved that these methods are within the range of the astronauts’ capabilities. Environmental factors, such as i) varied petrography, ii) varied number of thalli in test polygons, and iii) differences in topoclimatic conditions between the LIA moraine and the glacier front, further inhibited simple interpretation. The LIA maximum of the Kaunertal glacier occurred in AD 1850, and relative stabilization of the frontal part of the rock glacier occurred in AD 1711.

Techniques for retrospective analysis of size dynamics at annual resolution remain poorly developed in lichens in general, and fruticose lichens in particular. Only a few attempts in very high latitudes suggested that growth might be studied as a chronosequence of inter-nodal branch elongations. Here we evaluated, for the first time, this hypothesis in a dry Mediterranean environment using the lichen Cladonia rangiformis as a case study. Mixed models supported a strong positive relationship between humidity measured as precipitation/PET and inter-nodal branch elongations. Importantly, model selection suggested that (i) the number of intermodal elongations were a major determinant of stem elongation, and (ii) a second-order temporal autocorrelation denoted legacies of environmental influences at least over the next 2 y. The strong growth–humidity relationship, along with the potential legacies observed, support the idea that inter-nodal branch elongations could be used to reconstruct growth chronologies at annual resolution in drylands. This finding highlights the high vulnerability of these organisms to rising aridity, and opens a new venue for climate reconstruction and other potential applications in Ecology and Earth Science disciplines. • Inter-nodal branch elongations in Cladonia rangiformis represent annual growth in drylands. • Growth of C. rangiformis is highly responsive to precipitation in this Mediterranean site. • Autocorrelation in growth chronologies supports environmental legacies over time. [ABSTRACT FROM AUTHOR]

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. 1960–1973) have the potential to increase retreat rates significantly even during times of below average annual temperatures. [ABSTRACT FROM AUTHOR]

The eastern slope of Mt. Etna is characterised by shallow seismicity originating from normal-oblique faulting, Timpe Fault System, related to WNW-ESE regional extension. Recent research has demonstrated that in the fault population of Mt. Etna's eastern flank the minimum earthquake magnitude that will have a ground rupture effect is ca. 2.5. This system is characterised by high frequency seismic activity, due to thinned seismogenic crustal layer. This characteristic, together with the high density of the fault segments, does not always for identification of the segments responsible for the earthquake. The earthquakes, affecting the medium-lower eastern flank, have been historically reconstructed by macroseismic analysis and reported in a macroseismic database, and in recent decades by instrumental seismic registration, which provide the seismological parameters capable of evaluating focal mechanism, hypocentre and relative algorithms related to geometric parameters which control the growth of fault segments. In this paper, we present a methodology to evaluate the age of the rapid exhumation of the free-face fault plane of the NNW-SSE oriented normal fault segment named S. Tecla (Timpe Fault System). It consists of the measurement of the thalli species (Lichenometry method) in order to evaluate the parameters which characterise their growth. The seismic history of the S. Tecla Fault indicates eight certain events from 1865 to 2005 with 3.4 ÷ 4.7 Magnitude (De Guidi et al., 2012 and reference therein). We found evidence of two different recent rapid vertical deformation events at the base of the S. Tecla fault escarpment, the oldest 20 m long and 0.25 m in height, and the youngest with a 0.02 m high nude surface exposed. We have observed that there are thalli of Xanthoparmelia conspersa (Ehrh. Ex Ach.) Hale, colonizing part of the nude surface on the escarpment. The results highlight that the oldest thalli was dated at 43.7 years old, showing that rapid vertical deformation generated the surface where the thalli, after 4 years, took root. The displacement of this surface could be related to the seismic events occurring on 3rd August 1973 (3.8 M) in S. M. Ammalati area probably accompanied by intense post seismic deformation. The second and last event could be attributable to a 3.1 M seismic event occurring on 25th September 2014 (ISIDe, 2016). [ABSTRACT FROM AUTHOR]

The most heavily glacierized tropical range in the world — the Peruvian Cordillera Blanca — has been losing ice since the end of the Little Ice Age (LIA). In this study, the decline of the Churup glacier (9°28′18″ S; 77°25′02″ W) and associated processes were documented employing multi-proxy approach including the analysis of remotely sensed images (1948–2016), the Schmidt hammer rock test and lichenometric dating. It is shown that Churup glacier has lost the vast majority of its estimated LIA extent (1.05 ± 0.1 km2; 45.0×106 − 57.4×106 m3). The rate of glacier retreat is documented to vary in space (SE, SW and NW-facing slopes) and time, with the peak between 1986 and 1995. With an area of 0.045 km2 in 2016, it is expected that the complete deglaciation of the Churup valley is inevitable in the near future. Recently (post-LIA) exposed bedrock surfaces have shown higher R-values (54.2–66.4, AVG 63.3, STDEV 2.9) compared to pre-LIA exposed surfaces (46.1–59.3, AVG 50.1, STDEV 4.9), confirming the links to the duration of rock weathering. The Lichenometric dating is applied to recently exposed areas and elevations above 4800 m a.s.l., revealing only limited reliability and agreement with the age of deglaciation estimated from remotely-sensed images in such an environment. [ABSTRACT FROM AUTHOR]

The study of moraines at the Avacha volcano group revealed that glaciers changes at all volcanoes within the group happened almost synchronously. Glacial deposits could be grouped into three generations, corresponding to three periods of glacier fluctuations in Neoholocene. The largest glaciation within the group occurred ~2000 years ago. Fragments of moraine, corresponding to that period were found only in the moraine complex of the Ditmar Glacier which was 15% larger then today at that time. The most of moraines at the Avacha volcano group were formed during the Little Ice Age, which in the studied region continued up to the first decades of XX centuries. The maximal advance of glaciers probably happened in XVII century. The moraine corresponding to that period was found at the Kozelsky Glacier valley. At present time the total area of glaciers which moraines were described and dated approaches 21.46 km2. The area of reconstructed moraines corresponding to the Little Ice Age is estimated to be 2.79 km2, therefore at that period the total glaciation area reaches 24,25 км2 exceeding the present area by 13%. It could be claimed that in general during the time past the Little Ice Age the glaciation nature and glacier types did not change sufficiently. The rate of glacier degradation at various parts of the group is different and depends mainly on exposition. At the valleys of four glaciers we found moraines formed in the middle of XX century. They may appear in 1941–1952 when the unfavorable weather conditions leaded to stable negative anomalies in accumulation have happened.

We focused our study on the retreat of a typical valley glacier Kashkatash, located in the Elbrus Area. We compared the old photographs of the glacier forefields (H. Burmester, 1911; H. Altberg, 1927; E.N. Lukasheva, 1932; unknown author, 1939) with the aerial photograph of 1957, 1965, 1987, maps of scale 1:100 000 (1890) and 1:25 000 (1950s), satellite images (CORONA of 1971, ASTER of 2005, EROS of 2006), oblique photographs taken in 1980s–2000s and plans, created by different researches. Using cartographic material and old photographs we reconstructed 14 positions of glacier tongue over the last 120 years. We estimated the linear glacier retreat and the age of numerous stadial moraines basing on geomorphic, tree-ring and lichenometric data and correlated our results with previous sparse glacier fluctuation reconstructions in this region. We identified at least 13 end moraines within the distance of 900 meters from the up-to-date glacier front position. The minimum age of the outer moraine is 450 years according to the tree-ring data. One tree growing on this moraine was damaged by a boulder falling down from a younger moraine under formation in the period from autumn 1839 to spring 1840. Three moraines were deposited in 1870s–1890s. In 20th century the glacier advanced in 1910-s, 1920-s, and 1970–1980-s.

In this article we present the reconstruction of fluctuations of Alibek valley glacier situated in the Teberda valley, Western Caucasus. The former positions of glacier of the past 120 years were reconstructed basing on the old photographs of 1904, 1921, remote sensing data of 1955, 1987, 2007, 2008 and 2012, plans created in 20th century. Since the middle of 20th century Alibek Glacier decreased by 650 m in length and by 0,67 km2 in area and its tongue has risen by 110 m.

Using instrumental archives, aerial photographs, satellite images, old maps, descriptions of early explorers and old photographs we identified and mapped nine front positions of the Ullukam Glacier (SW slope of Elbrus) for the period from the end of XIX to the early XXI centuries. In 1884–2009 glacier retreated by 775 m. It advanced from 1971 to 1987 (36 m). The glacier fluctuations in the previous period were reconstructed using geomorphologic data, lichenometry, modern and buried soil description and radiorarbon analyses. We identified three Little Ice Age moraines of almost equal magnitude when the Ullukam Glacier was 889 m longer than in 2009. Two later advances occurred in the first third to middle of XIX century and in 1870s The recent fluctuations of the Ullukam Glacier closely correspond to the retreat two other glaciers in Elbus area. The location of the buried soil in the valley of Ullukam glacier brings evidence that the glacier have not advanced lower than 2813 m a.s.l. at least during the last four thousand years.

Residual strength and diameters of lichen Rhizocarpon sp. were measured on different elements of the Late Holocene glacial-cryogenic morphosculpture of frontal parts of glaciers № 29 and 31 in the Suntar-Khayat Range. All in all, 180 lichenometric sites (about 1000 individual measurements of Rhizocarpon sp.) and 150 sites for testing the residual strength of rebound value were organized, on which 380 estimations of this parameter (5674 individual measurements) were performed. For lichenometric index of age (minimal time of exposure) we used statistics RH5 that was a mean value from five maximal individuals on a local site; for index of rebound value Q that was a mean value from 80-100 unit measurements on the same site was taken. Using of data obtained at different times by aerospace surveys made it possible to derive the relationship between the RH5 statistics and time t of the morphosculptures exposure: RH5 = 0.0535t + 0.29. On the basis of regression coefficients of RH5 and Q indexes the equation RH5 = 69209e-0,136Q had been deduced as well as the equation connecting residual strength (rebound value) Q and time t of surface exposure: t = (69209e-0,136Qvalue– 0,29)/0,0535. Basing on the equations above, age of the moraine belts of the above glaciers was estimated. The most developed moraine belt, now placed apart from the present-day glacier edges at a distance of 600–700 m, was found to be formed for the whole Little Ice Age. Glaciers reached their maximum volumes during its first phase, i.e. during cold period of 13-15th centuries. Area of glacierization exceeded its current size by 35–40%. Glaciers remained at their almost steady state until middle of 19th century and then began to retreat slowly. By middle of 20th century, glaciers shortened by 5–7%. The most intensive shrinking of these glaciers started in the second half of 20th century.

Folklore surrounding an abandoned cemetery located in Johnson County, Arkansas (a part of the Louisiana Purchase) suggested that it was used by early settlers. Historical records were combined with several dating techniques to determine the approximate time periods that Cedar Grove Cemetery was established and abandoned. Cores extracted from trees located adjacent to or on graves provided evidence that the cemetery was abandoned in the 1920s. These results coincide with the last burial event in 1922. The approximate age of undated gravesites was determined using lichenometry. A lichen growth rate of 0.0685 cm/year was determined for lichens present on two gravestones with known dates. This growth rate was then applied to the undated graves to establish their approximate ages. Death dates from historical records of individuals buried in the cemetery matched the dates established by the lichen growth rate. Our results show that many of the unmarked graves date prior to the first documented private ownership of the land. The results of this study support local folklore passed down over several generations about the origin of the cemetery. [ABSTRACT FROM AUTHOR]

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Outburst floods originating in moraine-dammed lakes represent a significant geomorphological process as well as a specific type of threat for local communities in the Cordillera Blanca, Peru (8.5°–10° S; 77°–78° W). An exceptional concentration of catastrophic floods has been reported from the Cordillera Blanca in the first half of 20th Century (1930s–1950s), leading to thousands of fatalities. The main objective of this paper is to provide a revised and comprehensive overview of geomorphologically effective floods in the area of interest, using various documentary data sources, verified by analysis of remotely sensed images (1948–2013) and enhanced by original field data. Verified events (n = 28; 4 not mentioned before) are analysed from the perspective of spatiotemporal distribution, pre-flood conditions, causes, mechanisms and geomorphological impacts as well as socioeconomical consequences, revealing certain patterns and similar features. GLOFs are further classified according to their magnitude: 5 extreme events, 8 major events and 15 minor events are distinguished, referring to the quantified geomorphological and socioeconomical impacts. Selected moraine dams and flood deposits are dated using lichenometric dating. Special attention is given to moraine dam breaches - the most frequent type of water release with the most significant consequences. Selected major events and their consequences are studied in detail in a separate section. Finally, a general schematic model of lake formation, growth and post-flood evolution reflecting initial topographical setting and glacier retreat is introduced and the utilization of the obtained results is outlined. [ABSTRACT FROM AUTHOR]

Lichenometry can be a useful tool to date past events when surface ages are unknown. As a method, lichenometry needs to overcome uncertainties in the understanding of lichen biology. Being fairly ubiquitous, Rhizocarpon geographicum is generally used for dating purposes. Other lichens can and have been used for studies, but are often used in conjunction with R. geographicum. This case study suggests that for areas lacking R. geographicum, Rhizoplaca chrysoleuca may be used as an alternate species if the substrate in question does not have substantial R. geographicum growth. While R. geographicum is well-studied, R. chrysoleuca is not, and growth curves have not been established to any extent close to those for R. geographicum. This study uses an alluvial fan in Rocky Mountain National Park created by a dam breach in 1982 as a preliminary baseline to establish a basic R. chrysoleuca growth curve. Age of the substrate is known and was previously unexposed inside a glacial moraine. Assuming lichen growth began soon after the exposure, and as R. chrysoleuca represents the majority species at the site, a basic growth curve can be established, at least in alpine environments. This initial assessment can potentially aid researchers using lichenometry in alpine environments and, more specifically, where sufficient R. geographicum is not present. [ABSTRACT FROM AUTHOR]

In arid landscapes across the globe, aeolian processes are key drivers of landscape change, but arid Arctic regions are often overlooked. In the Kangerlussuaq region of West Greenland, strong katabatic winds have removed discrete patches of soil and vegetation, exposing unproductive glacial till and bedrock. Although lake-sediment records suggest that landscape destabilization began approximately 1000 years ago, the upland soil erosion has never been directly dated. We use a novel application of lichenometry to estimate the rates and timing of soil erosion. We show that the formation of deflation patches occurred approximately 800-230 years ago, in general agreement with lake-sediment records. In West Greenland, the 'Little Ice Age' (AD 1350-1880) was characterized by a cold and arid climate, conditions that increased susceptibility to erosion. On average, deflation patches are expanding at a rate of 2.5 cm yr-1, and variation in the rate of patch expansion cannot be explained by proximity to the Greenland Ice Sheet (GrIS), slope, aspect, elevation, or patch size. An erosional threshold exists in this aeolian system, with climate conditions necessary for patch formation likely harsher than those necessary for continued patch expansion, a result that has implications for land management in arid regions. Currently, deflation patches are expanding throughout the study region and are forming in areas close to the GrIS, but future deflation rates are dependent on projected climate and potential land-use changes. Our results stress the importance of aeolian processes in arid polar landscapes such as Kangerlussuaq, and demonstrate the use of aeolian landforms in paleoclimate reconstructions and predicting future landscape change. [ABSTRACT FROM AUTHOR]

Understanding the process of primary succession is a relevant topic in restoration and global change ecology, and provides the basis for classic dating methods in geomorphology, such as lichenometry and dendrochronology. The aim of this study is to investigate the colonization by lichens and vascular plants of two pro-glacial chronosequences encompassing the late- and mid-Holocene periods in the sub-Antarctic sub-region of South America. We use this information to address questions related to the pattern of Magellanic forests recovery after disturbance and the applicability of lichenometry for developing glacier retreat chronologies. Progression of succession to a state with high vascular plant cover was slow, and some moraines remained unforested for about 2000 years. Our results contrast with previous reports indicating a quick development of mature forest states on disturbed terrains, suggesting large regional variability on the course of succession. Environmental conditions seem propitious for lichens that colonize immediately after moraine formation. Lichens grow at relatively high rates in comparison to other world areas, but half as fast as in Antarctica and sub-Antarctic islands. Growth rates for the Rhizocarpon Ram. em. Th. Fr. sub-gen. Rhizocarpon group increase with lichen sizes up to ca. 50 mm and decrease in larger thalli, leading to a sigmoidal lichenometric growth curve that extends the applicable range of lichenometry to the last 5700 years in dry sites in the Magellanic province of the sub-Antarctic sub-region. Our results suggest that lichenometry is an effective technique in multi-proxy approaches for reconstructing glacier fluctuations, and agree with early studies in Antarctica suggesting that lichen annual growth rate is a sensitive attribute for the biomonitoring of climate changes. [ABSTRACT FROM AUTHOR]

On the northern coast of the Hornsund fjord at SW Svalbard, numerous rock block accumulations flank the foot of Rotjesfjellet ridge. Whereas these accumulations are widely described as rock glaciers, this study shows that other factors also influence formation of these landforms. In this study, morphometric profiling and terrain analyses, lichenometry, optical granulometry, Schmidt hammer measurements, geophysical measurements using electric resistivity tomography, geodetic measurements using terrestrial LiDAR and rockfall modelling were used to clarify the formation of one unusual block accumulation. The morphometric analysis of a detailed (0.5 m) DEM and relief profiles showed distinctly different morphology of one of four studied block accumulations. The electric resistivity tomography revealed an ice core in the accumulation, the Schmidt hammer sampling helped to establish relatively younger age of the lobe-like left part of accumulation and finally, the lichenometry was employed to place the event on the approximate position on the timescale. In conclusion, the unusual block accumulation is a result of two consequent processes: first, a typical foothill rock glacier has developed, and consequently a large rock avalanche occurred, adding material and deforming the NW part of the accumulation. Based on the results of lichenometry, the rock avalanche was estimated to be 250 ± 50 years old. The study thus presents one of the few reported slope deformation events from the recently deglaciated Arctic areas. [ABSTRACT FROM AUTHOR]