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The article presents a study regarding the effect of deglacial meltwater when spread into the ocean circulation. It mentions the model of Mier-Reimer and colleagues which is the Hamburg Large Scale Geostrophic (LSG). It states that stadial and interstadial background glacial climate condition produces different reversing rates in the North Atlantic.

This paper explores the resizing, reshaping and connectivity of islands by examining ongoing relations between land and sea in the context of the Channel Island of Guernsey. Ideas of materiality, temporality and vertical depth are employed to explore how contemporary tides and past sea‐level change impact island–island connections, and island–mainland connections between Guernsey and France. By focusing on the littoral zone as a space of encounter between land and sea, the paper explores some of the processes that challenge the notion of an island having fixed edges, emphasising the island's shape and size as always in flux. The paper then explores how tides alternatively reveal and hide material structures such as rocks and causeways, making the underwater scape temporally visible and differently accessible as an extension of land. It enables connections to be made and remade. This is demonstrated through the example of Guernsey and the tidal island of Lihou. The paper subsequently considers these ideas in the context of Quaternary sea‐level change. The land known as Guernsey alternated between literal island surrounded by water, and a steep‐sided plateau on the Normanno‐Breton plain, coinciding with interglacials and glacials. This connection is referred to as geologic. I argue that by acknowledging Guernsey's former visible connection with France, lack of contemporary visibility in the underwater scape does not render this a disconnection. Rather, the geologic, as further evidenced in the contemporary natural and built environment of Guernsey, continues through an underwater scape. It reappears in other Channal Islands and France, demonstrating ongoing connections at a land–sea–geologic interface. The paper argues for geology as a form of vertical depth. It calls for greater consideration of the geologic in the human geographical study of islands. [ABSTRACT FROM AUTHOR]

We show that in order to have a scaling description of the climate system that is not inherently non-stationary, the rapid shifts between stadial and interstadial conditions during the last glaciation cannot be included in the scaling law. The same is true for the shifts between the glacial and interglacial states in the quaternary climate. When these events are omitted from a scaling analysis we find that the climate noise is consistent with a 1/f law on time scales from months to 105 years. [ABSTRACT FROM AUTHOR]

In this paper, we present a reconstruction of climate conditions during the Last Glacial Maximum on a karst plateau Snežnik, which lies in Dinaric Mountains (southern Slovenia) and bears evidence of glaciation. The reconstruction merges geomorphological ice limits, classified as either clear or unclear, and a computer modelling approach based on the Parallel Ice Sheet Model (PISM). Based on extensive numerical experiments where we studied the agreements between simulated and geomorphological ice extent, we propose using a combination of a high-resolution precipitation model that accounts for orographic precipitation combined with a simple elevation-based temperature model. The geomorphological ice extent can be simulated with climate to be around 6 °C colder than the modern day and with a lower-than-modern-day amount of precipitation, which matches other state-of-the art climate reconstructions for the era. The results indicate that an orographic precipitation model is essential for the accurate simulation of the study area, with moist southern winds from the nearby Adriatic Sea having a predominant effect on the precipitation patterns. Finally, this study shows that transforming climate conditions towards wetter and warmer or drier and colder does not significantly change the conditions for glacier formation. [ABSTRACT FROM AUTHOR]

Small intermountain river basins are most suitable for developing new methods to estimate water balance due to their well-defined catchment boundaries, relatively rapid runoff processes, and accessible landscapes for study. In general terms, dissecting the hydrograph of a small mountain river requires calibration of the flow model against multi-year data sets, including (a) glacier mass balance and snow water content, (b) radiation balance calculation, (c) estimation of the groundwater contribution, and (d) water discharge measurements. The minimum primary data set is limited to the precipitation and temperature distributions at the catchment. This approach postulates that the conditions for the formation of all components of river flow are known in advance. It is reduced to calculating the dynamic balance between precipitation (input part) and runoff, ablation, and evaporation (output part). In practice, accurately accounting for the inflow and outflow components of the balance, as well as the impact of regulating reservoirs, can be a challenging task that requires significant effort and expense, even for the extensively researched catchments. Our studies indicate the potential benefits of an approach based on one-time, but detailed, observations of stable isotope composition, temperature, and water chemistry, in addition to standard datasets. This paper presents the results of the 2022–2023 work conducted in the basin of the small mountain river Ala-Archa, located on the northern slope of the Kyrgyz Range in Tien-Shan, which was chosen as an example due to its well-studied nature. Our approach could identify previously unknown factors of flow formation and assess the time and effectiveness of work in similar conditions. [ABSTRACT FROM AUTHOR]

Level 2 Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-based cloud datasets from 2012 are investigated for metrics that help distinguish the cirrus cloud presence of in autonomous lidar measurements, using temperatures, heights, optical depth and phase. A thermal threshold, proposed by Sassen and Campbell (2001; SC2001) for cloud top temperature Ttop≤ -37 °C, is evaluated vs. CALIOP algorithms that identify ice-phase cloud layers alone using depolarized backscatter. Global mean cloud top heights (11.15 vs. 10.07 km a.m.s.l.), base heights (8.76 vs. 7.95 kma.m.s.l.), temperatures (-58.48 °C vs. -52.18 °C and -42.40 °C vs. -38.13 °C, 10 respectively for tops and bases) and optical depths (1.18 vs. 1.23) reflect the sensitivity to these competing constraints. Over 99% of all Ttop ≤-37 °C clouds are classified as ice by CALIOP Level 2 algorithms. Over 81% of all ice clouds correspond with Ttop &#8804-37 °C. For instruments lacking polarized measurements, and thus practical phase estimates, Ttop ≤-37 °C proves stable for distinguishing cirrus, as opposed 15 to the risks of glaciated liquid water cloud contamination occurring in a given sample from clouds identified at warmer temperatures. Uncertainties in temperature profiles use to collocate with lidar data (i.e., model reanalyses/sondes) may justifiably relax the Ttop ≤-37 °C threshold to include warmer cases. The ambiguity of "warm" (Ttop >-37 °C) ice cloud genus cannot be reconciled completely with available mea20 surements, however, conspicuously including phase. Cloud top heights and optical depths are evaluated as potential constraints, as functions of CALIOP-retrieved phase. However, these data provide, at best, additional constraint in regional samples, compared with temperature alone, and may exacerbate classification uncertainties overall globally. [ABSTRACT FROM AUTHOR]

The freshwater discharge from melting ice sheets in the deglaciation or glaciation is prone to anomalies in ocean-atmosphere transport between different latitudes, which can lead to a series of abrupt millennial-scale climate events, either obvious or not, such as the Younger Dryas (YD) events and YD-like events. Marine Isotope Stage 11c (MIS 11c) serves as one of the best references for the current Holocene, and the studies of possible YD-like events and their triggering mechanisms during Holocene are conducive to the understanding of the occurrence pattern of extreme climate events. In this paper, the results of the study on the J33 δ18O sequence records of stalagmites in Jinfo Cave, Chongqing, are shown: (1) Stalagmites in the Asian monsoon climate zone reveal a millennial-scale weak monsoon event that occurred around 410 ka BP prior to the Glacial Maximum of MIS 11 interglacial period. (2) Both the 410 ka weak monsoon event and the YD event occurred during the gradual strengthening of the monsoon and ascending branch of summer insolation in the Northern Hemisphere prior to the Glacial Maximum of interglacial period. This was also a time when Atlantic Meridional Overturning Circulation (AMOC) disturbance occurred. The duration, internal structure, and pattern of the events were similar, with differences in the change magnitude and ice volume conditions. (3) The weak monsoon event that occurred in 410 ka BP was primarily influenced by the combined effects of insolation and AMOC. This event was characterized by a sustained warming process that accelerated the melting of the Greenland ice sheet, leading to the destabilization of this ice sheet. The continuous flowing of freshwater into the North Atlantic resulted in a short-lived AMOC oscillation. The weakening of the AMOC resulted in a cold anomaly over the North Atlantic. As a result of atmospheric telecorrelation, the weaker AMOC led to a weaker Asian Summer Monsoon (ASM). [ABSTRACT FROM AUTHOR]

Uniformitarian scientists were surprised to discover channels on Mars like the Channeled Scablands of eastern Washington. Climate models indicate that large-scale Martian floods are impossible. This paper will describe what appear to be flood features on Mars. Three types of channels on Mars are described in this paper: valley networks, outflow channels, and gullies. Like the Solar System's other solid bodies that have not been resurfaced by debris and volcanism, Mars possesses numerous impact craters, some very large, which provide a framework for the planet's history. Secular uniformitarian scientists divide the geologic history of Mars into four main periods which span 4.5 billion years. [ABSTRACT FROM AUTHOR]

Basal gravel and sand mantling the bedrock floors of buried valleys throughout the Canadian Interior Plains, and conformably overlying proglacial lacustrine sediment, comprise the Empress Group. While previously conceptualized as stratigraphically equivalent deposits of preglacial rivers prior to the first and most extensive continental and montane glaciations, subsequent stratigraphic studies indicated that buried valley basal gravel must have been deposited between, or during, progressively more extensive continental glaciations and could not be stratigraphically equivalent throughout the buried valley network. However, in the general absence of formation-rank stratigraphic description of basal gravel units that might better inform the geologic history of the deposits, most workers simply consider Empress Group sediments time-transgressive. In this paper, we examine basal gravel at provincial and regional scales to understand its genesis and geologic history. At the provincial scale, we map basal gravel in three dimensions using a novel machine learning approach. At the regional scale, we formally define basal gravel formations at either end of the largest buried valley system in Alberta, which informs its glacial history and physiographic development and shows the importance of formation-rank stratigraphic description. Our results indicate that the buried valley network across Alberta is palimpsest in genesis and basal gravel units within it are chronostratigraphically intercalated between tills. We advocate that the Empress Group definition be extended across Alberta with modifications to improve its clarity and utility, and formally define the Old Fort, Unchaga, Ipiatik, and Winefred formations as part of the Empress Group. [ABSTRACT FROM AUTHOR]

Orbital precession has been linked to glacial cycles and the atmospheric carbon dioxide (CO2) concentration, yet the direct impact of precession on the carbon cycle is not well understood. We analyze output from an Earth system model configured under different orbital parameters to isolate the impact of precession on air‐sea CO2 flux in the Southern Ocean—a component of the global carbon cycle that is thought to play a key role on past atmospheric CO2 variations. Here, we demonstrate that periods of high precession are coincident with anomalous CO2 outgassing from the Southern Ocean. Under high precession, we find a poleward shift in the southern westerly winds, enhanced Southern Ocean meridional overturning, and an increase in the surface ocean partial pressure of CO2 along the core of the Antarctic Circumpolar Current. These results suggest that orbital precession may have played an important role in driving changes in atmospheric CO2. Plain Language Summary: Over the past one million years, Earth has experienced several glacial and interglacial periods. As a glacial period is ending, carbon in the atmosphere can rise by up to 50%. The cause for this change is currently unknown, but most theories suggest that this carbon is released from the deep ocean into the atmosphere. The Southern Ocean surrounding Antarctica is the location of a lot of carbon outgassing from the deep ocean into the atmosphere, so it could be responsible for some of this change in atmospheric carbon. One of Earth's orbital cycles, precession, has been shown to change circulation in the Southern Ocean, that can affect how much carbon is carried from the deep ocean to the surface and released into the atmosphere. This paper uses simulations of a climate model to show that high precession corresponds to a 20% increase in the release of carbon from the Southern Ocean into the atmosphere. These findings suggest that precession could have affected changes in past atmospheric carbon concentrations. Key Points: Increased insolation during austral summer due to orbital precession shifts the southern westerlies polewardPoleward shifted westerlies enhance CO2 outgassing due to increased turbulent exchange and vertical transport of carbon‐rich watersEnhanced transport of carbon‐rich waters is driven by a deepening of the overturning circulation in response to poleward shifted winds [ABSTRACT FROM AUTHOR]

The total air content (TAC) of polar ice cores has long been considered a potential proxy for past ice sheet elevation. Recent work, however, has shown that a variety of other factors also influence this parameter. In this paper we present a high-resolution TAC record from the South Pole ice core (SPC14) covering the last 54 000 years and discuss the implications of the data for interpreting TAC from ice cores. The SPC14 TAC record shows multiple features of interest, including (1) long-term orbital-scale variability, (2) millennial-scale variability in the Holocene and last glacial period, and (3) a period of stability from 35 to 25 ka. The longer, orbital-scale variations in TAC are highly correlated with integrated summer insolation (ISI), corroborating the potential of TAC to provide an independent dating tool via orbital tuning. Large millennial-scale variability in TAC during the last glacial period is positively correlated with past accumulation rate reconstructions as well as δ15 N-N 2 , a firn thickness proxy. These TAC variations are too large to be controlled by direct effects of temperature and too rapid to be tied to elevation changes. We propose that grain size metamorphism near the firn surface explains these changes. We note, however, that at sites with different climate histories than the South Pole, TAC variations may be dominated by other processes. Our observations of millennial-scale variations in TAC show a different relationship with accumulation rate than observed at sites in Greenland. [ABSTRACT FROM AUTHOR]

In the summer of 1838, Arnold Guyot was asked by Louis Agassiz to gather information on Alpine glaciers, with the aim of reporting their findings in September, at the annual gathering of the French Geological Society. Guyot's observations of the internal structure of the ice and interpretations on glacier movements, reported orally at the conference, were new to science. Unfortunately, because of purported illness, Guyot did not send his manuscript to be published and missed his first opportunity to be recognized as a pioneer in glacier studies. During the years 1841 to 1847, Guyot published a series of notes, detailing results of his field work in tracing erratic blocks in the central Alpine region, in the Alpine foreland and in the Jura Mountains. The level of detail in his work was unprecedented and has not been replicated since. Recognizing that erratic blocks of similar lithology could be followed along organized paths of deposition, Guyot could invalidate those theories that sought to explain their deposition by chaotic means, such as floods, debacles or drifting icebergs loaded with rock debris. Only moraines, composed of material transported by glaciers, could explain the mapped arrangements of erratic blocks. Geological proofs for extensive glaciations in central Europe had just been found, and Guyot could demonstrate them on his hand-drawn map. But, in 1848, a revolution broke out in Neuchâtel. The local academy where Guyot was engaged as a professor shut down and all staff were left without pay. Answering a call from Agassiz who had emigrated to the USA in 1846, Guyot departed Switzerland and joined his friend there in the fall of 1848. In his luggage were all the papers on his unfinished project, including his map, and a full collection of erratic rock specimens. After arrival in the USA, Guyot had to begin a new professional life and could not devote significant attention to the subject of erratic blocks. In 1849, he showed his map of the erratic basins of Switzerland and discussed his results with various members of the American Association for the Advancement of Science (AAAS); he also shared his novel ideas about the climatic conditions required for the formation of large glaciers; however, he did not formally publish the results of his work in the Alps, and he thus lost his second opportunity for wider peer recognition and for driving the acceptance of the glacial theory. Only in 1874, 26 years after his arrival in the USA and a year after Agassiz's death, did Guyot open his boxes of alpine rock specimens and display his unpublished map in the Museum of the College of New Jersey (later Princeton University), where he was engaged as a professor. In 1883, at age 77, his memory of the unpublished 1838 report on glaciers was still in his conscience which finally pushed him to submit it for printing at Neuchâtel. It passed largely unnoticed, however, and Guyot died one year later without recognition attached to his name for his original, innovative work. This paper reviews Guyot's work and analyses his relationship with Agassiz while both were working in Neuchâtel. It seeks to evaluate his pioneering work on glaciers and on erratic blocks. It includes a copy of Guyot's map of the erratic basins of Switzerland, kept to this day in the archives of Princeton University. [ABSTRACT FROM AUTHOR]

Natural analogues are systems that have evolved over geological timescales with features similar to one or several components of a deep geological repository (DGR). Natural analogues complement short-duration laboratory studies since they are existing reflections of many long-term processes that might affect the performance of a repository. Mathematical models are often used for the post-closure safety assessment of a DGR. Confidence in the models' predictions is enhanced when the models successfully simulate the past evolution of a natural analogue. This paper summarizes the Canadian Nuclear Safety Commission's (CNSC's) recent research on natural analogues to inform on (1) glacial erosion, (2) engineered barrier system, and (3) uranium reactive transport in the context of DGRs for radioactive wastes. Glaciation and its erosion are prominent factors impacting the performance of future DGRs at high latitudes in the northern hemisphere. The authors have reviewed the field data from the Greenland Analogue Project, developed a conceptual and mathematical model for the simulation of the thermal conditions within the Greenland ice sheet, as well as the thermal-hydraulic conditions at its base and the ice sheet velocity, and eventually estimated the erosion rate at the site. The Cigar Lake Analogue demonstrates the long-term radionuclide containment capability of the illite clay zone enveloping the ore body, serving as an analogy to the engineered clay barriers. The CNSC and University of Ottawa analyzed 129I in the Cigar Lake core samples, and modeled and correlated the diffusion-dominated transport of radionuclides over the geological evolution of the Cigar Lake deposit. The results provide information on the mobility of fission products and significant radionuclides in conditions analogous to the source, engineered barriers, and near-field host rock of a DGR. The reactive transport and geochemistry of the Kiggavik-Andrew Lake uranium deposit mineralization and remobilization was another natural uranium deposit analogue studied by the CNSC. A reactive transport model was established according to the conceptualized geochemical processes and run under specified boundary and initial conditions to validate the geochemical processes. The geometry, timing, geochemistry, and fluid composition were used as model constraints. [ABSTRACT FROM AUTHOR]

The study of alluvial terraces helps in reconstructing the past geometries of rivers and makes it possible to assess the rate and pattern of fluvial incision and bedrock uplift. The fluctuations of river base levels are particularly variable and complex during the Late Quaternary in the lower course of rivers due to the interplay of responses to sea‐level fluctuations, tectonics and glacio‐isostasy. In this paper, the geometry and chronology of Manoir Brésil, an outcrop of alluvial terraces of the Lower Seine River, northern France, are investigated through a multidisciplinary study. Fluvial incision during MIS 8 in the Lower Seine in relation to sea‐level drop is recorded by an erosional surface cut into the chalk bedrock. This surface is covered by MIS 7 tidal deposits and then by younger, mostly periglacial colluvium (head). Manoir Brésil is therefore considered to be a chronological equivalent of the nearby, well‐studied Tourville‐la‐Rivière outcrop. The deposits are affected by post‐MIS 7 cryoturbation processes. Based on the local elevation of MIS 7 tidal deposits and erosional surfaces at Manoir Brésil, a minimum bedrock uplift rate of 25–40 m/Ma and an erosion rate of 125 m/Ma during glacial periods can be proposed. A regional correlation of the MIS 8 erosional surface is increasingly deformed by uplift towards the North, making it difficult to correlate the fluvial deposits along the Seine without precise chronological control. We interpret this regional tilt as the result of isostasy rebound after glaciations, consistent with the distribution of the elevations of MIS 5e and MIS 7 marine deposits along the English Channel. [ABSTRACT FROM AUTHOR]

This paper presents an updated geological reconstruction of the Quaternary evolution of the River Thames at its downstream extremities, close to the North Sea coast, based on new data from multi-disciplinary and citizen-science sources. In this area, the interaction of the Thames with the MIS 12 (Anglian) glaciation is an important part of the Quaternary archive. The Anglian ice sheet, which reached parts of north and east London, was responsible for diverting the Thames southwards into its present course, although the footprint of the maximum ice sheet(s) does not reach the North Sea coast south of Hollesley, Suffolk. Further south, the coastal zone hosts pre-Anglian and early Anglian river-terrace deposits of the pre-diversion Thames system, superimposed upon which are products of later post-Anglian rivers, of both Middle and Late Pleistocene age. On the peninsula between the Stour and Blackwater–Colne estuaries, the lowest and most recent terrace of the pre-diversion Thames includes evidence directly pertaining to the glacial disruption event, for which geochronological data are reported here for the first time. The first post-diversion terrace of the Thames also reaches this peninsula, the river having essentially re-joined its original valley before crossing the alignment of the modern coastline. This terrace passes beneath Clacton-on-Sea, where it includes the type locality of the Clactonian Palaeolithic Industry. The area of interest to this paper, in NE Essex and southern Suffolk, includes a number of interglacial and Palaeolithic sites, the data from which assist in constraining the chronostratigraphy of the sequence. In some cases, there has been uncertainty as to whether these sites represent pre-Anglian environments and hominin occupations, part of the palaeo-Thames sequence, or whether they are the product of later post-Anglian streams, formed after the Thames had migrated southwards. This paper compiles evidence from a wide range of recent sources, including developer-funded archaeological appraisal and citizen-science activities, to explore and update the evidence from sites at Ipswich, Upper Dovercourt and Thorpe-le-Soken, as well as a number of localities associated with the Clacton Channel Deposits (host to the type-Clactonian), amongst others. The resulting new data are placed within the wider context of the Quaternary fluvial archives in southern Britain, with a discussion of how disparate sources of information, including the work of citizen scientists, have contributed. [ABSTRACT FROM AUTHOR]

This paper addresses the effect of fractures within crystalline bedrock on glacial erosion processes in fast flowing hard bed glacier environments. In particular, we examine (i) whether the fracture type is critical for the capability of a glacier to erode the bedrock through quarrying/plucking processes and (ii) whether we can recognize specific fracture‐controlled erosion signatures from bedrock surface morphologies. We conducted an investigation within the northern part of the Åland Islands, southern Finland, where the ice‐flow direction (N–S) has remained constant through Late Pleistocene glaciations and where the bedrock is characterized by a lack of any mesoscopic anisotropies (such as foliation) and hence provides an optimal target to recognize the relationships between fractures and erosional morphologies. We characterized the fracture systems within the bedrock using both UAV‐acquired orthophotographs and standard field approaches and extrapolated the results to larger scales using LiDAR‐based digital elevation models. Our findings indicate that individual joints or shear fractures are associated with the development of minor vertical breaks along the bedrock surface. However, they do not provide sufficient mechanical weakness zones in the bedrock to allow effective glacial quarrying, even though their lengths can be relatively large (>50 m). By contrast, the linkage of several parallel shear fractures or the presence of larger faults with gouge‐bearing cores and well‐developed damage zones leads to localized disintegration of the rock material and the subsequent development of distinct topographic depressions along the bedrock surface. Consequently, the results allow predictions to be made about the bedrock features underlying the observed topographic signatures along the bedrock surface. Applied to the area of this investigation, abrasion associated with N–S‐directed glacial flows is responsible for the N–S‐oriented elongate but smooth fjord‐like megagrooves, whereas the more abrupt topographic breaks were generated by quarrying controlled by sub‐vertical, E–W‐trending zones of localized brittle deformation. [ABSTRACT FROM AUTHOR]

In recent years, the evolution of the magnetic flux lobes in terms of location and intensity has been attributed to paleosecular variation of the geomagnetic field, reflecting outer‐core fluid convection close to the core‐mantle boundary. However, most results were based on observational data for the past 400 years supplemented by sparse archeomagnetic studies with data for approximately 3 kyr. In this paper, we construct a relative paleointensity (RPI) record and an inclination record spanning the past ∼90 kyr based on two cores from Tengchong Qinghai Lake (Yunnan Province, China), a closed crater lake that formed in the late Pleistocene. The evolution of flux lobes and the non‐dipole field can be assessed on a much longer time scale. Although the concentration and domain state of magnetic grains in the cores vary significantly, the RPI record is still representative of geomagnetic field features in the region of Yunnan Province, China. The contrasting trends in RPI with the records for eastern China since the late Holocene indicate the southeastward migration of the Siberian flux lobe. During the last glacial period, the RPI records of Tengchong Qinghai Lake and the North Atlantic Ocean show opposite trends, denoting the diverse and strong influence of the two flux lobe systems. The strong reverse flux lobe in the North Atlantic Ocean strengthened the non‐dipole field, while the weak normal flux lobe in Tengchong weakened the non‐dipole field. Plain Language Summary: Earth's magnetic field is composed of two main field components: a dipole field and a non‐dipole field. Although the non‐dipole field constitutes a minor component of the geomagnetic field, its variations in strength and location over different time scales have a significant influence on the surface expression of the geomagnetic field. The flux lobes arising from the fluid convection at the boundary between the core and mantle may produce the main components of the non‐dipole field. In recent years, the distribution of magnetic flux has been discussed based mainly on instrumental data and archeomagnetic data spanning a few kyr, which limits our understanding of flux lobe evolution on a much longer time scale. In this paper, we reconstruct a relative paleointensity (RPI) and an inclination records over the past ∼90 kyr from sediments of a closed volcanic lake in Tengchong, Yunnan Province, China. The results show that the RPI in the Tengchong area differs from the records for eastern China in the Holocene and from the records in the North Atlantic Ocean during the last glacial period. We conclude that a flux lobe may have played an important role in the non‐dipole field in the Tengchong and in the North Atlantic Ocean. Key Points: High‐resolution paleosecular variation records, including relative paleointensity (RPI) and inclination for the past 90 kyr, are derived from sediments in a closed lake in ChinaThe Holocene RPI trend obtained differs from records from records from eastern China, indicating the movement and intensification of the Siberian flux lobeThe opposing RPI patterns from the lake and the North Atlantic Ocean during the last glacial period indicate the influence of flux lobe systems on the non‐dipole field [ABSTRACT FROM AUTHOR]

This paper presents sedimentological and paleobotanical studies of the deposits from Last Glaciation (Late Nemunas, Late Weichselian) in the middle reaches of the River Nemunas in southern Lithuania. Spores, pollen, and other palynomorphs in the intercalated sediments between the diamicton (glacial till) beds were analyzed, and the paleogeographical and paleoclimatic conditions of their sedimentation were assessed using the modern analog technique (MAT). The two till layers from the Last Glaciation, characterized by significant differences in their composition, testify to a difference in glacier movement paths in the region. The continuous sedimentation process between glacial tills provides evidence of global climate changes during the Last Glaciation and the restructuring of glacial lobes during deglaciation in the southeastern part of the Scandinavian Ice Sheet. The sedimentation process and vegetation composition bear witness to an open landscape of steppe-tundra, scattered wooded areas, and the emergence of thermophilic vegetation afterward, suggesting increased annual temperatures and higher humidity. The available data enable the identification of the Balbieriškis interstage period within the Late Nemunas Glaciation (Upper Nemunas Formation) between the Grūda and Baltija stages (Grūda and Baltija subformations) in the regional Quaternary stratigraphic scheme. This period correlates with the Marine Isotope Stage 2 (MIS 2). [ABSTRACT FROM AUTHOR]

A complete, fluvial stratigraphic record for the last glacial period of the Western Andes in Peru is not available due to preservation issues and spatial variability in sedimentation. Deposits are typically restricted to incomplete records of fluvial terraces or localised occurrences of alluvial fans and landslides. These landforms are thought to have formed under a regime of climate cyclicity controlling increases in precipitation. Because of the fragmented preservation of these deposits, as well as dating uncertainties, it remains unclear if orbital climate cycles, such as the precession cycle, or suborbital cycles, such as the wet Heinrich events, are driving Andean sedimentation. In this paper, we try to answer this question through a sedimentological–stratigraphical analysis of a much more complete sedimentary sequence than usually found in the region. We present the results of a grain size analysis of 5000 clasts and 13 new luminescence ages of a 52‐m‐long, stratigraphic section of the Lima fluvial fan in Peru. Bayesian age–depth modelling resulted in a robust chronostratigraphic framework and derived sedimentation rates. The stratigraphic record registered sedimentation from 121.7 ± 4 to 6.3−1.6+1.5 ka. Three major sedimentation periods occurred between 121.7 to 110−5+4, 87 ± 1 to 67−3+2, and 31−3+4 to 6.3−1.6+1.5 ka. These periods registered various unconformities and coarsening–fining upward sequences which chronologically correlate to suborbital pluvial periods, recognised from speleothems and lake records, that drove fluvial deposition. They also correlate with the timing of other recognised sedimentation events throughout the Western Andes. Marine regression resulted in fan progradation and not in incision. The Lima fan stratigraphy represents therefore the most complete, last glacial fluvial record for the Peruvian Western Andes to date and it highlights the potential of fluvial fans as recorders of suborbital climate variability. [ABSTRACT FROM AUTHOR]

Upper Palaeolithic archaeological sites in the Basque Country have been excavated for over a century. They have yielded a rich palaeoenvironmental record with zoological and botanical remains that have been obtained in stratigraphic series dated precisely by radiocarbon. This information reveals cyclical environmental changes from climates similar to today to drier and extremely cold conditions, when species in current boreal biomes and others now extinct but with similar ecological preferences were present in the region. Moreover, the archaeological sites have provided high-resolution information about the resilience mechanisms of the communities of our own human species. This information allows us to increase the corpus of palaeoclimate data regarding the Marine Isotopic Stage (MIS) 2 and MIS 3 for a critical region within the human population of Eurasia. The aim of this paper is to show how an extraordinary capacity for adaptation to drastic climate changes Upper Palaeolithic hunter–gatherer societies displayed, even though their subsistence depended on biotic resources that alter rapidly. [ABSTRACT FROM AUTHOR]

This paper reviews the IUFRO lecture series, Forest Roads: regional perspectives from around the world. In reviewing the presentations in this series, we found that regional factors such as geology, historic climate (glaciation), current climate, topography, and ownership strongly affect forest road networks. In addition to these regional factors, it appears that historic land use affects road design and construction. We define three road classifications: pioneer, mature, and plantation. In a pioneer road network, there is an existing forest resource and no established road network. A pioneer road network strongly reflects the current regulatory environment, current harvesting systems, and regional factors. A plantation road network occurs where there is a land use change, often from agriculture to forestry, and often growing non-native species. Plantation road networks evolve from existing rudimentary roads to road networks planned specifically for a well-defined forest resource. The plantation road network does reflect the existing regulations and harvesting systems; however, it does exist in a more constrained system that is defined by the existing roads and the boundaries of the planted forest. Mature forest road networks have evolved over centuries and incorporate historic and current land use, evolving regulations and technology, and are often interconnected with public roads. Responses specific to these road classes include a pioneer road network using brush mats to help support the subgrade, a plantation road network applying an optimized design, and a mature road network using pavement as the road surface. [ABSTRACT FROM AUTHOR]

The glacial trough is a common glacier erosion landscape, which plays an important role in the study of glacier erosion processes. In a sharp contrast with the developing river, which is generally meandering, the developing glacial trough is usually wide and straight. Is the straightness of the glacial trough just the special phenomenon of some areas or a universal feature? What controls the straightness of the glacial trough? Until now, these issues have not been studied yet. In this paper, we conduct systematic numerical models of the glacier erosion and simulate the erosion evolution process of the glacial trough. Numerical simulations show that: (1) while the meandering glacier is eroding deeper to form the U-shaped cross section, the glacier is eroding laterally. The erosion rate of the ice-facing slope is bigger than that of the back-slope. (2) The smaller (bigger) the slope is, the smaller (bigger) the glacier erosion intensity is. (3) The smaller (bigger) the ice discharge is, the smaller (bigger) the glacier erosion intensity is. In the glacier erosion process, the erosion rate of the ice-facing slope is always greater than that of the back-slope. Therefore, the glacial trough always develops into more straight form. This paper comes to the conclusion that the shape evolution of the glacial trough is controlled mainly by the erosion mechanism of the glacier. Thereby, the glacial trough prefers straight geometry. [ABSTRACT FROM AUTHOR]

Simple Summary: Italy plays a central role in the research on Europe's biogeography because of its position in the middle of the Mediterranean, which is a global hotspot of diversity. This study investigated how present patterns of earwig species richness and composition in Italy are affected by climatic, geographical, and historical factors. Earwig richness does not decrease from the base to the tip of the Italian peninsula, which contrasts with the so-called 'peninsula effect'. However, richness does not increase southward either, suggesting that southern regions did not play a crucial role as a refuge during Pleistocene glaciations. Inter-regional similarities in species composition between regions is more influenced by their geographical proximity than climatic similarity, although richness is positively correlated with precipitation, in accordance with earwig preferences for humid conditions. The similarity in species composition with central European fauna decreases southward, indicating possible exchanges between central Europe and Italy. The majority of the earwigs of the Italian fauna are either widespread across Europe and the Palearctic, or confined to the main Italian mountain ranges, that is, the Alps and the Apennines. The isolation of ancient earwig populations on mountains resulted in the development of a high proportion of endemics, making the Italian earwig fauna one of the richest in Europe. Placed in the center of the Mediterranean biodiversity hotspot, Italy plays a central role for the study of Europe's biogeography. In this paper, the influence of climatic, spatial, and historical factors on current patterns of variation in earwig species richness and composition is investigated. The Italian earwig fauna is mainly composed of species which are either widely distributed in Europe and the Palearctic region or that are endemic to the Alps and the Apennines. Variation in species richness does not follow any obvious geographical patterns, but a positive influence of precipitation on richness is consistent with earwig preferences for humid climates. European mainland territories did not contribute substantially to the current biodiversity of Italian earwigs, which explains the lack of a distinct peninsula effect, although a southward decrease in similarity with the central European fauna was observed. However, southern areas did not exert a pivotal role during Pleistocene glaciations in determining current patterns of species richness. Variation in species composition among Italian regions can be mostly explained by geographical proximity, while climatic differences and historical (paleogeographical and paleoecological) events seem to have played a minor role. However, the isolation of ancient earwig stocks on Italian mountains led to the origin of a relatively large number of endemics, which makes the Italian earwig fauna one of the richest in Europe. [ABSTRACT FROM AUTHOR]

Clues of climate change on the Alashan Plateau since the last glacial period (40 ka) are important for revealing the mechanism of desertification of middle-latitude deserts in the Northern Hemisphere (NH). Studies are still rare for the understanding of the specific relationship of climate changes between the Alashan Plateau and the global. Based on a systematic and comparative analysis of the existing research in China and the international academic community, this paper reviews the environmental evolution history of the Alashan Plateau since the last glacial period from the records of paleo-environment and geomorphological characteristics in different deserts of the plateau (e.g., Badanjilin, Tenggeli, and Wulanbuhe). From about 40 ka to the end of the last glacial maximum, the climate on the plateau was wetter than it is today, and to the end of the Pleistocene, the climate was generally dry and the aeolian activities were enhanced. However, the climate was arid during the whole last glacial period in the Wulanbuhe Desert, evidently different from the overall pattern of the plateau. The Tenggeli Desert was characterized by an arid climate in the early Holocene. The most controversial events for the Alashan Plateau are the drought events in the middle Holocene in the Badanjilin Desert. The role and impact of the westerlies and the East Asian Summer Monsoon (EASM) systems on the climate change of the desert and even the whole plateau is a vexed question that brings different views in different periods. There is still a lack of definite evidence representing the events of global environmental change that occurred on the plateau during the discussed period. The distinctive morphology of dune mountains and the distribution of sand dunes are mutually indicative of the direction and energy of wind systems on the plateau. It is suggested that appropriate wind energy is the significant key to the desertification in these middle-latitude deserts on the plateau. From a global-scale review of climate change, the desertification of the modern-scale sandy desert landscapes on the Alashan Plateau is generally related to the global glacial period and the cold and dry climate during the past 40 ka. [ABSTRACT FROM AUTHOR]

This paper presents five sites located in the marginal zone of the Wartanian stadial within the Odranian Glaciation (MIS6a) on the border of the Central Polish Uplands and Lowlands, representing different glacial forms and geological structures: terminal moraine hill, undulating moraine hill, sedimentary margin of the ice sheet, kame hill, and outwash plain. This differentiation is also reflected in the petrographic composition of the gravels and the interesting surface microstructures of the Scandinavian erratic boulders. This small study area, with its high geodiversity, which we have identified and investigated, has considerable potential for sustainable development. Geotourism is a tool for this development in a peripheral tourist region, providing both economic benefits for the local population and conservation services for the geoecosystem. [ABSTRACT FROM AUTHOR]

Rockslides are a major hazard in mountainous regions. In formerly glaciated regions, the disposition mainly arises from oversteepened topography and decreases through time. However, little is known about this decrease and thus about the present-day hazard of huge, potentially catastrophic rockslides. This paper presents a new theoretical concept that combines the decrease in disposition with the power-law distribution of rockslide volumes found in several studies. The concept starts from a given initial set of potential events, which are randomly triggered through time at a probability that depends on event size. The developed theoretical framework is applied to paraglacial rockslides in the European Alps, where available data allow for constraining the parameters reasonably well. The results suggest that the probability of triggering increases roughly with the cube root of the volume. For small rockslides up to 1000 m3, an exponential decrease of the frequency with an e -folding time longer than 65,000 yr is predicted. In turn, the predicted e -folding time is shorter than 2000 yr for volumes of 10 km3, so that the occurrence of such huge rockslides is unlikely at present times. For the largest rockslide possible at present times, a median volume of 0.5 to 1 km3 is predicted. With a volume of 0.27 km3, the artificially triggered rockslide that hit the Vaiont reservoir in 1963, is thus not extraordinarily large. Concerning its frequency of occurrence, however, it can be considered a 700 to 1200-year event. [ABSTRACT FROM AUTHOR]

This paper presents a new complete field mapping of glacial landscapes, landforms and sediments in the Faroe Islands, supplemented by observations from bathymetric maps of the Faroe Shelf. In addition, previous investigations of Quaternary and especially the Weichselian glaciation of the archipelago are reviewed. New cosmogenic nuclide exposure ages indicate that the last extensive glaciation of the Faroe Islands occurred during the Late Weichselian, most likely during the Last Glacial Maximum (LGM; c. 26.5-19.0 cal. ka BP), although a Younger Dryas (c. 12.9-11.7 cal. ka BP) age cannot be entirely excluded. Geomorphological mapping provides a background for reconstructing the extent and type of the glaciation of the Faroe Islands. The reconstructed Weichselian glaciation appears to have had the character of an extensive valley glaciation, with several marine glacier termini. The present glaciation of southern Spitsbergen, Svalbard, represents a modern analogue of the reconstructed Weichselian glaciation in the Faroe Islands. The lack of raised coastal features in the Faroe Islands, also at protected sites, suggests that postglacial isostatic uplift was smaller than post-LGM eustatic sea level rise. Numerical glacier reconstructions carried out for different extents of the last extensive Faroese glaciation suggest that such limited postglacial isostatic crustal uplift requires that the Faroe Shelf was not extensively glaciated during the Late Weichselian, but it doubtless was so during at least one of the previous Quaternary glaciations. [ABSTRACT FROM AUTHOR]

The Sowie Mountains in the central part of the Sudetes range are an under-researched area in terms of geomorphology, despite their potential representativeness for a large number of terrains within the Bohemian Massif, built of metamorphic bedrock. Apart from providing an overview of past work, the paper summarizes the main topographic features of the massif using visualizations of the digital terrain model, and outlines the wide range of anthropogenic impacts on relief. Characteristic landforms of the Sowie Mountains include faultgenerated lithology-controlled escarpments, ridge-and-valley topography near the escarpments, water-divide flats, gneissic tors, agrarian terraces and various landforms related to former mining and military use. [ABSTRACT FROM AUTHOR]

Morphological phases of moraines from north-oriented valleys are known in the Bohemian Forest. Detailed data from south-oriented valleys are still missing. This paper presents morphological phases of moraines from two valleys. Glacial landforms were defined by an accurate digital elevation model (DEM) and verified by field mapping. The extent and internal structure of the selected glacial landforms were refined by geophysical profiling. We have described 8 morphological phases of moraines in the Großer Schwarzbach cirque locality (south orientation) and 4 morphological phases of moraines in the Kleiner Rachelbach cirque locality (north orientation). In the north-oriented valley, the number of morphological phases of moraines corresponds to other north-oriented sites in the Bohemian Forest. In the south-oriented valley, the number of morphological phases of moraines exceeds the number of morphological phases of moraines in the north-oriented sites in the Bohemian Forest. [ABSTRACT FROM AUTHOR]

This paper describes the course of migration and expansion of small mammals in the Makalu Barun region influenced by the orogenetic uplift of the East Nepal Himalaya and climatically conditioned changes in the extent of morphogenetic zones from the Upper Pleistocene up to the present. The results of zoological and parasitological research are compounded with the knowledge of the dynamic development of landforms, which testifies to significant changes in the high-mountain environment during the Quaternary. The migration of Palearctic species of small mammals across the gradually emerging orographical barrier during the orogenesis of the High Himalaya was completely interrupted by the glaciation in the Upper Pleistocene. This extensive glaciation also excluded occurrence and survival of small mammals in the high-mountain valleys of the Makalu Barun region. Migration routes and the extension of the territory of small mammals remained open only in the periglacial zone of the Arun and Barun Khola valleys. Following the interstadial period of warmer and humid climate conditions were changed by the Late Glacial Maximum when small mammals were again pushed away from heavily glaciated valleys to the lower altitude periglacial zone. During the Holocene interglacial, the occurrence of fauna and flora in the high-mountain valleys depended on repeated spatial changes of periglacial and glacial morphoclimatic zones. Current biogeographical hazards are accentuated due to the rapid retreat of glaciers, the expansion of the periglacial morphoclimatic zone and the increased human impact in the High Himalaya. [ABSTRACT FROM AUTHOR]

Former proglacial lakes provide insight into the temporal and spatial evolution of past ice sheet dynamics and the glaciohydrological systems associated with them. Glacial Lake Pickering was a proglacial lake in North Yorkshire impounded by the British–Irish Ice Sheet. However, geomorphic evidence for its existence and extent is weak and contested. This paper presents, for the first time, systematic mapping of geomorphic features from high‐resolution (50 cm to 5 m) digital terrain model data and undertakes palaeogeographical reconstructions to establish Palaeolake Pickering's extent and levels. Results show only weak evidence for a 70‐m lake. This and the fact that the present landscape configuration is unable to impound such a large lake suggests that it either did not exist or is much older and that considerable landscape erosion has since taken place. There is good geomorphological evidence to support lake levels between 45 and 20 m. The new palaeogeographical reconstructions show these lake levels were initially controlled by the balance between the North Sea and the Vale of York Lobes of the British–Irish Ice Sheet with lower and later levels impounded by the Filey moraine. A multi‐stage Palaeolake Pickering with various extents and levels possibly spanning more than one glacial period has implications for other British–Irish Ice Sheet palaeolake extents reconstructed only from undifferentiated lacustrine sediments and their maximal elevation. The existence of an extensive multi‐phase proglacial Palaeolake Pickering along with other similar ones in Eastern England would have impacted mass loss and frontal dynamics via subaqueous melting and iceberg calving, potentially playing a role in controlling the dynamic behaviour of the North Sea Lobe. [ABSTRACT FROM AUTHOR]

This database of Phanerozoic occurrences and isotopic characteristics of metastable cold-water calcium carbonate hexahydrate (ikaite; CaCO 3 ⚫6H 2 O) and their associated carbonate pseudomorphs (glendonites) has been compiled from academic publications, explanatory notes, and reports. Our database including more than 700 occurrences reveals that glendonites characterize cold-water environments, although their distribution is highly irregular in space and time. A significant body of evidence suggests that glendonite occurrences are restricted mainly to cold-water settings; however they do not occur during every glaciation or cooling event of the Phanerozoic. While Quaternary glendonites and ikaites have been described from all major ocean basins, older occurrences have a patchy distribution, which may suggest poor preservation potential of both carbonate concretions and older sediments. The data file described in this paper is available on Zenodo at 10.5281/zenodo.4386335 (Rogov et al., 2020). [ABSTRACT FROM AUTHOR]

Palaeoglacier modelling is an important approach for reconstructing the palaeoclimate. The timing of glaciations in the central part of the Gangdise Mountains has been constrained previously, but the palaeoclimate remains unclear. In this paper, the palaeo-temperature and precipitation of the early marine isotope stage (MIS) 2, the Last Glacial Maximum (LGM), and the early Holocene were reconstructed using coupled mass balance and ice flow models. The results show that a series of temperature changes (ΔT) and precipitation factors (Fp) resulted in optimum palaeoglacial extents. The modelled palaeoglaciers during the early MIS 2, the LGM, and the early Holocene cover areas of ~18.1 km2, ~17.4 km2, and ~16.3 km2, respectively, with ice volumes of ~2.18 km3, ~1.99 km3, and ~1.95 km3, respectively. Previous studies on ice cores, pollen samples, and lake sediments were referenced to narrow the range of palaeo-temperatures and precipitations. The reconstructed temperatures during the early MIS 2, LGM, and early Holocene were constrained to 2.4–2.9 °C, 2.15–3.05 °C, and 0.95–1.5 °C lower than today, respectively. Their precipitation levels were 60–80%, 50–80%, and 100–150% of the present-day level, respectively. [ABSTRACT FROM AUTHOR]

A new ice core drilled at the South Pole provides a 54 000-year paleoenvironmental record including the composition of the past atmosphere. This paper describes the SP19 chronology for the South Pole atmospheric gas record and complements a previous paper (Winski et al., 2019) describing the SP19 ice chronology. The gas chronology is based on a discrete methane (CH 4) record with 20- to 190-year resolution. To construct the gas timescale, abrupt changes in atmospheric CH 4 during the glacial period and centennial CH 4 variability during the Holocene were used to synchronize the South Pole gas record with analogous data from the West Antarctic Ice Sheet Divide ice core. Stratigraphic matching based on visual optimization was verified using an automated matching algorithm. The South Pole ice core recovers all expected changes in CH 4 based on previous records. Gas transport in the firn results in smoothing of the atmospheric gas record with a smoothing function spectral width that ranges from 30 to 78 years, equal to 3 % of the gas-age–ice-age difference, or Δ age. The new gas chronology, in combination with the existing ice age scale from Winski et al. (2019), allows a model-independent reconstruction of the gas-age–ice-age difference through the whole record, which will be useful for testing firn densification models. [ABSTRACT FROM AUTHOR]

This paper suggests a selection criterion of the continuous method version for a numerical solution of the Stefan problem which would allow to calculate the phase transition boundary position with a required accuracy for a long period of time and would enable generalization to multidimensional problems. Despite a large number of works deal with the solution to the generalized Stefan problem by the continuous method, the choice of the smoothing interval value for numerical feasibility is not fully clear. A comparison of the calculation accuracy of the phase transition boundary position using different versions of the continuous method was carried out on an example of the well-known 1-D plane two-phase Stefan problem which possesses an analytical solution. The dependence of the total error of the numerical calculation of the phase transition boundary position on the value of the smearing interval is determined from the comparison of numerical and analytical solutions. An analysis of the reason for increase of this error with time at any choice of a constant smoothing interval is given. A version of the continuous method with a variable interval of the delta function smoothing, in which the proposed criterion is carried out, is discussed. The position of the phase transition boundary calculated proposed version matches the analytical solution with a required accuracy over a long period of time. [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070115 [ABSTRACT FROM AUTHOR]

Models (paradigms) and former interpretations have often been presupposed when conducting field research. In the 19th century diamictites were for the first time interpreted to have originated from ancient glaciations. These interpretations have to a large part prevailed in the geological community, although there has been much progress in the areas of sedimentology, glaciology and physical geography. The present work is an effort to find criteria which most clearly discriminate between geological features produced by different processes, mainly glaciation and mass flow, the latter predominantly sediment gravity flows. Geological features which have been interpreted to have formed by glaciation throughout pre-Pleistocene Earth history are compared to similar-appearing geological features formed by mass flow and tectonics, so as to uncover variations in the appearance between features resulting from these different processes. The starting point for this comparison is documentation of the appearance of Quaternary products of erosion and deposition, in order to discern the origin of older formations. It is shown that the appearance and origin of pavements, dropstones, valleys, small-scale landforms, surface microtextures and most other geological features may in some cases be equivocal, but in others the details are indicative of the process which generated the feature. Detailed geological field data which have been compiled by geologists from outcrops of pre-Pleistocene strata, more often than is considered in most papers, commonly point to a mass flow origin, mainly a sediment gravity flow origin, rather than a glaciogenic origin. A process of multiple working hypotheses or interpretations is therefore advocated, based mainly on a comparison of the appearance of features formed by different geological processes documented from different research disciplines. Instead of starting with current interpretations or models, this multiple working hypothesis or methodology helps to avoid confirmation bias and jumping to conclusions. [ABSTRACT FROM AUTHOR]

Climatic and environmental conditions play a pivotal role in the evolution of the biosphere, serving as the primary natural factors influencing biological evolution and the development of human civilization. The study of the evolution of Earth's habitability primarily revolves around the reconstruction of climatic and oceanic conditions in geohistorical periods, shedding light on their dynamic changes. This paper collates classic geological indicators and geochemical proxies associated with paleo-climatic and oceanic environmental conditions. The latest "big data" analyses and simulations made possible by the availability of previously unimagined massive datasets reveal several key findings: During the early Paleozoic, atmospheric oxygen levels were low, and widespread oceanic anoxia was prevalent; the Devonian era witnessed a greenhouse climate, followed by the Carboniferous ice age characterized by higher oceanic oxidation levels and alkalinity. The latest Paleozoic deglaciation occurred under high pCO2 conditions, extending into much of the Mesozoic and early Cenozoic, marked by multiple hyperthermal and anoxia expansion events, until the resurgence of global glaciation in the middle-late stages of the Cenozoic, ultimately bringing environmental and climatic conditions closer to modern levels. By correlating the aforementioned long-term trends with major geological events, we can delineate the co-evolution of paleoclimate and oceanic environments in tandem with the development of Tethys tectonics as follows. (1) During the Proto-Tethys stage, global paleo-elevations were relatively low, and atmospheric oxygen levels were also relatively modest. Despite the occurrence of significant tectonic movements that led to noticeable transgressive-regressive cycles, their effects on climate and oceanic environments were somewhat limited due to the relatively weak interactions. (2) The emergence of the Paleo-Tethys was a significant event that coincided with the formation of the supercontinent Pangaea. Intensive orogenic movements during this period increased the global land area and elevation. This, in turn, led to enhanced terrestrial weathering, which elevated sea surface productivity and resulted in massive nutrient input into the oceans. Consequently, this process contributed to the rise of oxygen levels in the atmosphere and a decrease in atmospheric pCO2. These changes are considered potential driving mechanisms for late Paleozoic glaciation and oceanic oxygenation. (3) The transition from the Paleo-Tethys to the Neo-Tethys was closely linked to the breakup of Pangaea. During this period, the terrestrial weathering processes were relatively weak due to decreased continental elevations. This resulted in a long-term greenhouse climate and intermittent global oceanic events, which were responses to the high atmospheric pCO2 levels during the Mesozoic and early Cenozoic eras. (4) The Neo-Tethys stage ended with the dramatic uplift of the Alps-Himalaya Mountain ranges due to the collision of India and Asia. This uplift had a profound global impact, significantly increasing continental elevations. As a result, weathering and carbon burial processes intensified, leading to a reduction in atmospheric pCO2. Concurrently, this uplift played a crucial role in the establishment of the East Asian monsoon and North Atlantic deep-water circulations, both of which played a part in triggering the late Cenozoic ice age. These models suggest that the teleconnections between land and sea (orogeny-terrestrial weathering-marine carbon burial) span over the whole Phanerozoic and might have played a key role in balancing the Earth surface system. Combined, the tectonic, volcanic, paleo-climatic, as well as paleoenvironmental events recorded in the Tethys oceans and adjunct continents represent valuable natural experiments and lessons for understanding the present and the future of Earth's habitability. [ABSTRACT FROM AUTHOR]

Reconstructing the geologic history of a karst area can advance understanding of the system's present-day hydrogeologic functioning and help predict the location of unexplored conduits. This study tests competing hypotheses describing past conditions controlling cave formation in an alpine karst catchment, by comparing an ensemble of modeled networks to the observed network map. The catchment, the Gottesacker karst system (Germany and Austria), is drained by three major springs and a paleo-spring and includes the partially explored Hölloch cave, which consists of an active section whose formation is well-understood and an inactive section whose formation is the subject of debate. Two hypotheses for the formation of the inactive section are the following: (1) glaciation obscured the three present-day springs, leaving only the paleo-spring, or (2) the lowest of the three major springs (Sägebach) is comparatively young, so its subcatchment previously drained to the paleo-spring. These hypotheses were tested using the pyKasso Python library (built on anisotropic fast-marching methods) to generate two ensembles of networks, one representing each scenario. Each ensemble was then compared to the known cave map. The simulated networks generated under hypothesis 2 match the observed cave map more closely than those generated under hypothesis 1. This supports the conclusion that the Sägebach spring is young, and it suggests that the cave likely continues southwards. Finally, this study extends the applicability of model ensemble methods from situations where the geologic setting is known but the network is unknown to situations where the network is known but the geologic evolution is not. [ABSTRACT FROM AUTHOR]

The lack of evidence for large‐scale glacial landscapes on Mars has led to the belief that ancient glaciations had to be frozen to the ground. Here we propose that the fingerprints of Martian wet‐based glaciation should be the remnants of the ice sheet drainage system instead of landforms generally associated with terrestrial ice sheets. We use the terrestrial glacial hydrology framework to interrogate how the Martian surface gravity affects glacial hydrology, ice sliding, and glacial erosion. Taking as reference the ancient southern circumpolar ice sheet that deposited the Dorsa Argentea formation, we compare the theoretical behavior of identical ice sheets on Mars and Earth and show that, whereas on Earth glacial drainage is predominantly inefficient, enhancing ice sliding and erosion, on Mars the lower gravity favors the formation of efficient subglacial drainage. The apparent lack of large‐scale glacial fingerprints on Mars, such as drumlins or lineations, is to be expected. Plain Language Summary: Water accumulates under ice masses, including glaciers and ice sheets, lubricating the base of the ice and accelerating ice motion. On Earth, this glacial motion has produced scoured landscapes in northern Europe and North America. Mars lacks such large‐scale glacial erosion even in areas with other signs of widespread glaciation. This paper uses the existing framework describing the physical interactions of water and ice, and how they affect ice motion, to show that a lack of landforms recording glacial erosion is expected even if glaciation were widespread on Mars. Key Points: Glacial hydrology feedback dynamics can explain the lack of glacial sliding on the Martian geological recordSubglacial water drainage develops faster, and is more resilient under lower Martian gravityThe fingerprints of Martian wet‐based glaciation are predicted to be channels and eskers [ABSTRACT FROM AUTHOR]

Monitoring studies at the base site, the Aktru glacier basin (Severo-Chuisky glaciation center, central Russian Altai Mountains), have been ongoing for 22 years and correspond to the global focus of scientific efforts on the study of mountain ecosystems. This article describes the main approaches to monitoring mountain ecosystems and their climatic response based on the leading role of their autotrophic block, especially edificator species of Altai forest ecosystems: Siberian larch and Siberian stone pine. This paper presents the main results of monitoring in old-growth forests, the forest–tundra ecotone, and ecosystems emerging on young moraines of valley glaciers. The authors provide information about the life forms of Siberian stone pine and Siberian larch, the structure of forest stands, and the species diversity of communities. The formation of tree generations in the course of supersecular warming/cooling cycles and the relationship of tree growth with secular and intrasecular climatic changes are considered; a comparative analysis of seed cone production in forests and ecotones is carried out. The current position of the tree lines (groups and single trees, reproductive) in the forest–tundra ecotone is considered, and their shift upwards the slopes as a response to climate change is found. The course of primary successions on young moraines of the Maly Aktru and Levy Bolshoi Aktru glaciers is described. [ABSTRACT FROM AUTHOR]

The expansion of ice masses across southern Africa during the Late Palaeozoic Ice Age has been known for 150 years, including the distribution of upland areas in controlling the configuration of glaciation. In Namibia, increasing attention has focussed on long and deep palaeovalley networks in the Kaokoland region in the north, but comparatively little work has been attempted in the topographically subdued plains of the south, in the Aranos and Karasburg basins. The desert terrain of the Aranos area exposes diamictites of the Dwyka Group discontinuously over about 300 km, extending further south to the Karasburg area at the Namibian‐South African border along the Orange River. Whilst examined at a stratigraphic level, the nature of the contact between the Dwyka glacial rocks and underlying lithologies has not been systematically investigated. This paper presents the results from fieldwork in austral winter 2019, in which a highly varying basal contact is described that records the processes of growth, flow and expansion of ice masses across this part of Gondwana. At the basin margins, subglacially produced unconformities exhibit classic glacially striated pavements on indurated bedrock. In comparison, the basal subglacial unconformity in the more basinward regions is characterised by soft‐sediment striated surfaces and deformation. In the Aranos Basin, soft‐sediment shear zones originated in the subglacial environment. This type of subglacial unconformity developed over well‐differentiated, unconsolidated, siliciclastic materials. Where ice advanced over more poorly sorted material or cannibalised pre‐existing diamictites, 'boulder‐pavements' recognised as single clast‐thick boulder‐dominated intervals formed. Importantly, these boulder‐pavements are enriched in clasts, which were facetted and striated in‐situ by overriding ice. By integrating measurements of striation orientations, fold vergence and palaeocurrent information, former ice flow pathways can potentially be reconstructed over a wide area. [ABSTRACT FROM AUTHOR]

Thufur (earth hummocks) are small periglacial landforms typical for subpolar latitudes, as well as for the high alpine areas at lower latitudes. Their presence in the mountains of the Balkan Peninsula was spotted during the mid-20th century. In this paper we analyze morphometry and morphology of thufur in the context of physio-geographical conditions for their formation. The main aims are to inventorize the thufur in the study area and to determine the physio-geographical factors which enabled their formation at non-zonal elevations. Statistical analysis was performed on the sample of 305 thufur mapped in the field, measuring their circumference, height, and delineating their areas. Classification of the results revealed morphological varieties in terms of horizontal and vertical development. The elevation of the sampling location Ponor is 1,410 m a.s.l., which is considerably lower than the zonal periglaciation in Serbia, at approx. 1,900 m. Therefore, the role of relief as a climate modifier is analyzed in the context of conditions for the azonal development of periglaciation process. Topographical conditions for thufur formation were analyzed through slope inclinations and vertical dissection, determined using the Digital Elevation Model over Europe with 25 m resolution. [ABSTRACT FROM AUTHOR]

If a series of glacial advances occurs over the same pathway, the moraines that are now present may constitute an incomplete record of the total history. This is because a given advance can destroy the moraine left by a previous one, if the previous advance was less extensive. Gibbons, Megeath and Pierce (GMP) formulated an elegant stochastic model for this process; the key quantity in their analysis is $\bi P(n\vert N)$, the probability that n moraines are preserved after N glacial advances. In their paper, GMP derive a recursion formula satisfied by $\bi P(n\vert N)$, and use this formula to compute values of P for a range of values of n and N. In the present paper, we derive an explicit general answer for $\bi P(n\vert N)$, and show explicit, exact results for the mean value and standard deviation of n. We use these results to develop more insight into the consequences of the GMP model; for example, to a good approximation, 〈n〉 increases as ln(N). We explain how a Bayesian approach can be used to analyze $\bi P(N\vert n)$, the probability that there were N advances, given that we now observe n moraines. [ABSTRACT FROM AUTHOR]

The deglaciation record of the Ontario Lowland and Mohawk Valley of North America is important for constraining the retreat history of the Laurentide Ice Sheet, end-Pleistocene paleoclimate, and ice-sheet processes. The Mohawk Valley was an important meltwater drainage route during the last deglaciation, with the area around modern Oneida Lake acting as a valve for meltwater discharge into the North Atlantic Ocean. The Mohawk Valley was occupied by the Oneida Lobe and Oneida Ice Stream during the last deglacial period. Multichannel seismic reflection data can be used to generate images of preglacial surfaces and internal structures of glacial bedforms and proglacial lake deposits, thus contributing to studies of deglaciation. This paper uses 217 km of offshore multichannel seismic reflection data to image the entire Quaternary section of the Oneida basin. A proglacial lake and paleo-calving margin is interpreted, which likely accelerated the Oneida Ice Stream, resulting in elongated bedforms observed west of the lake. The glacial bedforms identified in this study are buried by proglacial lake deposits, indicating the Oneida basin contains a record of glacial meltwater processes, including a 60-m-thick proglacial interval in eastern Oneida Lake. [ABSTRACT FROM AUTHOR]

After the Elatina glaciation of Snowball Earth, at least four distinct glacial advances and sea-level retreats punctuated Ediacaran time: Gaskiers glaciation (580 Ma), Fauquier glaciation (571 Ma), Bou-Azzer glaciation (566 Ma) and Hankalchough glaciation (551 Ma). Tillites or diamictites are commonly controversial, but periglacial paleosols with distinctive physical structure and degree of chemical weathering offer supporting evidence of glaciation and sea-level change useful for stratigraphic correlation. This paper reviews glacial advances of the Ediacaran stratotype and other sequences, and also reveals the value of paleosols and chemical index of alteration to understand the upper Squantum and Brookline members of the Roxbury Conglomerate near Boston, Massachusetts. The Boston Bay ice wedges are periglacial paleosols, and evidence of maritime glacial climate like that of modern coastal Greenland and Arctic Canada. Simple discoidal vendobiont fossils (Aspidella terranovica) in the Dorchester Member of the Roxbury Conglomerate and in the Cambridge Argillite are in heterolithic shale–siltstone facies that are interpreted as intertidal to shallow marine environments. Local marine transgressions and other paleosols showing significant chemical weathering represent temperate interglacial paleoclimates. Short glacial advances affecting climate and sea-level enable subdivision of the Ediacaran Period. Four distinct glacial advances and sea-level retreats punctuated Ediacaran time: Gaskiers (580 Ma), Fauquier (571 Ma), Bou-Azzer (566 Ma), Hankalchough (551 Ma). Paleosols with distinctive structures such as ice wedges were periglacial. Squantum Member diamictites near Boston, Massachusetts are Gaskiers age. [ABSTRACT FROM AUTHOR]