Regional Glaciation Research Articles

A rare piedmont glaciation in the Mediterranean: Insights from cosmogenic 36Cl dating of Davraz hummocky moraine field (SW Türkiye)

AbstractPiedmont glaciers (lobes), typically found in high latitudes and large mountainous regions, extend from ice sheets and ice caps to lower altitudes. However, they can also occur, although less commonly, on mid‐latitude mountains. When these fan‐like glaciers retreat, they leave behind hummocky moraines scattered in a chaotic pattern. In this study, we have mapped one of these mid‐latitude sites and established a Terrestrial cosmogenic nuclide (TCN) glacial chronology on Mount Davraz, namely Davraz hummocky moraine field (37°46′00″N, 30°43′15″E). Our findings indicate that the glaciers in this area started receding from the early local Last Glacial Maximum (LGM) period (21.8 ± 2.4 ka) to the early Late‐glacial period (17.7 ± 2.2 ka), and eventually disappearing. The deglaciation of the Mt. Davraz palaeoglacier matches nearby mountains, supported by southerly winds as significant for regional glaciation. Our discoveries reveal a robust connection between southerly winds and nearby glaciation, contributing to our understanding of how climate influences glaciers. Likewise, the glacial timelines of the neighbouring mountains align with the glacial history of Mt. Davraz.

Drilling into a deep buried valley (ICDP DOVE): a 252 m long sediment succession from a glacial overdeepening in northwestern Switzerland

Abstract. The modern Alpine landscape and its foreland were strongly impacted by the numerous glacier advance and retreat cycles during the Middle-to-Late Pleistocene. Due to the overall erosive character of each glaciation cycle, however, direct traces of older glaciations tend to be poorly preserved within the formerly glaciated domains of the pan-Alpine area. Nevertheless, sediments of older glaciations may occur hidden under the modern surface in buried glacially overdeepened troughs that reach below the normal level of fluvial erosion (fluvial base level). These sedimentary archives, partly dating back to the Middle Pleistocene period, are of great scientific value for reconstructing the timing and extent of extensive Alpine glaciation, paleoclimate, and paleoenvironmental changes in the past and help to better understand ongoing and future changes in the pan-Alpine area. Therefore, the International Continental Scientific Drilling Program (ICDP) project DOVE (Drilling Overdeepened Alpine Valleys) targets several of these glacial overdeepened sedimentary basins to recover their sedimentary infills. In the frame of the DOVE project, a 252 m long drill core of unconsolidated Quaternary sediments was recovered in northern Switzerland from an over 300 m deep glacially overdeepened structure (“Basadingen Trough”) formed by the former Rhine Glacier lobe system. The recovered sedimentary succession was divided into three stratigraphic units on the basis of lithological and petrophysical characteristics. The lowest unit, deposited below the fluvial base level, consists of an over 200 m thick succession of glacial to (glacio)lacustrine sediments and contains remains of possibly two glaciation cycles. Overlying this lowermost succession, an ∼ 37 m thick fluvial-to-glaciofluvial gravel deposit occurs, which correlates to a locally outcropping Middle Pleistocene formation (“Buechberg Gravel Complex”). The sediment succession is capped by an ∼ 11 m thick diamictic succession interpreted as the subglacial till from the later extensive glaciation, including the regional glaciation during the Last Glacial Maximum. The recovered sediment succession thus supports the proposed multi-phase origin of trough formation and its infill.

Genomic clines across the species boundary between a hybrid pine and its progenitor in the eastern Tibetan Plateau

Most species have clearly defined distribution ranges and ecological niches. The genetic and ecological causes of species differentiation and the mechanisms that maintain species boundaries between newly evolved taxa and their progenitors are, however, less clearly defined. This study investigated the genetic structure and clines in Pinus densata, a pine of hybrid origin on the southeastern Tibetan Plateau, to gain an understanding of the contemporary dynamics of species barriers. We analyzed genetic diversity in a range-wide collection of P. densata and representative populations of its progenitors, Pinus tabuliformis and Pinus yunnanensis, using exome capture sequencing. We detected four distinct genetic groups within P. densata that reflect its migration history and major gene-flow barriers across the landscape. The demographies of these genetic groups in the Pleistocene were associated with regional glaciation histories. Interestingly, population sizes rebounded rapidly during interglacial periods, suggesting persistence and resilience of the species during the Quaternary ice age. In the contact zone between P. densata and P. yunnanensis, 3.36% of the analyzed loci (57 849) showed exceptional patterns of introgression, suggesting their potential roles in either adaptive introgression or reproductive isolation. These outliers showed strong clines along critical climate gradients and enrichment in a number of biological processes relevant to high-altitude adaptation. This indicates that ecological selection played an important role in generating genomic heterogeneity and a genetic barrier across a zone of species transition. Our study highlights the forces that operate to maintain species boundaries and promote speciation in the Qinghai-Tibetan Plateau and other mountain systems.

Comparison of overdeepened structures in formerly glaciated areas of the northern Alpine foreland and northern central Europe

Abstract. Overdeepened structures occur in formerly and presently glaciated regions around the earth and are usually referred to as overdeepenings or tunnel valleys. The existence of such troughs has been known for more than a century, and they have been attributed to similar formation processes where subglacial meltwater plays a decisive role. This comparison highlights that (foreland) overdeepenings and tunnel valleys further occur in similar dimensions and share many characteristics such as gently sinuous shapes in plan view, undulating long profiles with terminal adverse slopes, and varying cross-sectional morphologies. The best explored examples of overdeepened structures are situated in and around the European Alps and in the central European lowlands. Especially in the vicinity of the Alps, some individual troughs are well explored, allowing for a reconstruction of their infill history, whereas only a few detailed studies, notably such involving long drill core records, have been presented from northern central Europe. We suggest that more such studies could significantly further our understanding of subglacial erosion processes and the regional glaciation histories and aim to promote more intense exchange and discussion between the respective scientific communities.

Facies Composition and Stratigraphic Position of the Quaternary Upper Yenisei Sequence in the Tuva and Minusa Depressions

Abstract —The paper concerns the sediment sequence, which is widespread in the Yenisei valley and in the Tuva and Minusa depressions and also present in the valleys of the southern Chulym plain. The sediments of this sequence were previously described as “Neogene mud-shedding”, as well as moraines, alluvial fan deposits, alluvium of Middle Pleistocene high terraces, and lacustrine sediments. The giant ripple marks on the Upper Yenisei terraces was commonly interpreted as ribbed moraines; however, in recent studies, these ridges have been repeatedly referred to as marks of giant current ripples. Besides, some recently published papers provide description of geology of this sequence fragments suggesting its deposition by cataclysmic floods. Geomorphological analysis of the area shows Pleistocene glaciers to have been localized within the medium–high mountainous areas. The glaciers did not reach the Tuva and Minusa depressions and occupied large areas only in the Todzha basin and on the periphery of the Darkhat basin, forming a glacial dam at its outlet, which resulted in glacial-dammed lakes filling the basin completely. These lakes outburst, and the resultant flooding led to the deposition of megaflood sediments, which we refer to here as the Upper Yenisei sediment sequence. A detailed analysis of its facies architecture revealed similarity of these sediments to those of the Sal’dzhar and Inya sequences in Gorny Altai. Most of the Upper Yenisei megaflood sediments are localized in topographic lows of the Tuva and Minusa depressions. Beyond the Altai–Sayan mountainous area, the megaflood sediments of the Upper Yenisei sequence compose high terraces of the Yenisei, Chulym, Chet’, and Kiya rivers in the southern Chulym plain. The formation of Upper Yenisei sequence dates to the first half of the Late Pleistocene, inasmuch as it contains inset alluvial sediments of the second terrace of the Yenisei River. The available data allow suggesting that the Upper Yenisei sequence formed in the first Late Pleistocene regional glaciation. The Sal’dzhar sequence in Gorny Altai and the fourth terrace of the Ob’ River on the Fore-Altai plain are stratigraphic analogs of the Upper Yenisei sequence. The Upper Yenisei and Sal’dzhar sequences can thus be considered future regional markers serving as a link for the local stratigraphic schemes of the Altai–Sayan mountainous area and adjacent West Siberian plains. The results obtained call for verification by geochronological dating, first of all, by modern luminescence dating methods covering a wider chronological interval than radiocarbon dating.

Exploring the operational impacts of climate change and glacier loss in the upper Columbia River Basin, Canada

AbstractThe mountainous watersheds of western Canada are generally thought to be in a state of transition from snow‐dominated to hybrid regimes. In stream networks that are regulated, the effects of this transition on streamflow can have compelling operational consequences. Seasonal magnitude changes may impact spill‐risk management, while changes in the composition of summer runoff may increase its variability and reduce the forecasting capabilities of state variables like peak snow water equivalent. Though glacier loss can have a considerable impact on summer runoff, few studies explicitly model the ongoing glacier recession in conjunction with other primary hydrological processes. In this study, we incorporate glacier dynamics from a previous run of the Regional Glaciation Model into the University of British Columbia Watershed Model via the Raven modelling framework. We use this modelling system to explore potential changes under Representative Concentration Pathways 4.5 and 8.5 to the hydrology of the Mica Basin, a regulated watershed containing the headwaters of the Columbia River. Our results project statistically significant increases in spring flow in future eras, which may force lower reservoir drafting in late winter, creating potential for energy shortfalls in early spring. We project the coefficient of variation of summer runoff generally goes unchanged in future eras as does the summer runoff forecasting capability of April 1st SWE. Hence, despite modelled glacier loss and reduced snowmelt contribution, our study does not reject the null hypothesis that the predictability of the Mica Basin's summer runoff is unchanged in future eras. We explore these results in detail because they superficially appear to contrast the conventional conceptualization that reduced snowmelt negatively affects the predictive powers of snowpack and glacier loss increases the variability of runoff. We argue that our results' apparent discordance from convention displays the complexities inherent in isolating the effects of changes to a single water balance component when other components are also non‐stationary and highlights the benefits of using modelling to more explicitly explore such implications.

Revisiting the Nantuo Formation in Shennongjia, South China: A new depositional model and multiple glacial cycles in the Cryogenian

Increasing sedimentary records and non-glacial facies reported from various regional glaciations suggest diverse interpretation against the ‘hard’ snowball Earth. At Shennongjia, in northern Yangtze Craton, glaciogenic strata of the Nantuo Formation (~649–635 Ma) are widely outcropped, which represents the Marinoan glacial record. In this study, sedimentary logging of eight high-quality exposed sections of the Nantuo Formation were systematically conducted. Four facies associations were recognized: (i) diamictites, (ii) heterolithics, (iii) lonestone-bearing siltstone, and (iv) clast-free siltstone. The succession reveals significant spatial and lateral facies variation, therefore, the stratigraphic framework of Nantuo Formation could be compartmentalized into western, central and eastern types. Based on the facies associations analysed, the sequence stratigraphic method was applied to determine ice advance-retreat cycles in the region. Our data suggest the ice dynamic evolution is three-fold, comprising: (i) ice sheet moved from continental environment from eastern to the subglacial grounding zone in the western Shennongjia features first ice advance-retreat cycle, which is recorded by the lower member of Nantuo Formation; (ii) the second glacial episode is illustrated by glaciolacustrine and non-glacial lacustrine deposits in periglacial environment, which is indicated by the middle member of Nantuo Formation in western Shennongjia, though situation in rest parts of Shennongjia is unclear; (iii) the appearance of ice rafted deposits (IRD) in both western and eastern Shennongjia suggests ice-distal environments, alongside the siltstone on the top Nantuo Formation, representing final deglaciation period. Altogether three glacial advance systems tracts (GAST) were identified, separated by three glacial retreat systems tracts (GRST). Meanwhile, a general east–west direction ice sheet movement could also be reconstructed. Besides, based on sedimentology, notably the stacking patterns and clast character, we tentatively interpret the Nantuo glacier as the transitional type between temperate and polythermal glacier.

A statistical and numerical modeling approach for spatiotemporal reconstruction of glaciations in the Central Asian mountains

Reconstructing Quaternary regional glaciations throughout the Himalaya, Tibet, and the adjoining mountains in Central Asia is challenging due to geological biases towards limited preservation of glacial deposits and chronological uncertainties. Here, we offer several statistical and mathematical model codes in R, in excel, and in MATLAB useful to develop regional glacial chronostratigraphies, especially in areas with distinct orographically-modulated climate. A complete R code is provided to generate a regional climate map using Cluster Analysis (CA) and Principal Component Analysis (PCA). Additional R codes include reduced chi-squared, Chauvenet's criterion, radial plotter/abanico plot, finite mixture model, and Student's t-test. These methods are useful in reconstructing the timing of local and regional glacial chronologies. An excel code to calculate equilibrium-line altitudes (ELAs) and steps to reconstruct glacier hypsometry are also made available to further aid to our understanding of the extent of paleoglaciations. A MATLAB code of the linear glacier flow model is included to reconstruct paleotemperatures using the length and slope of a glacier during past advances.•R statistical codes can be used/modified without restrictions for other researchers.•Easy steps to calculate ELAs and glacier hypsometry from the same data.•Paleo-temperature reconstruction utilizes already developed glacial chronologies and maps.

200\xa0ka of glacial events in NW Svalbard: an emergence cycle facies model and regional correlations

Late Quaternary sedimentary units at Kongsfjordhallet, NW Svalbard, represent five cycles of glaciations and subsequent deglaciations during high relative sea levels. The high sea level events are interpreted as glacioisostatically induced and imply preceding regional glaciations, which we constrain in time by luminescence and radiocarbon ages to just prior to ~ 195, ~ 130, ~ 85, ~ 60, and ~ 15 ka. Combined with the stratigraphical record from nearby Leinstranda we identify six, possibly seven, major glacial advances during the last 200 ka in the Kongsfjorden region. Two of these occurred during the Saalian and at least four during the Weichselian. The results are based on detailed sedimentological, stratigraphical and chronological investigations of the uppermost 15 m of the 40-m-high Kongsfjordhallet coastal sections. The succession is dominated by sediments of marine and littoral origin, representing partial shallowing-upward sequences due to isostatic rebound. Only one subglacial till was recognised. Interestingly, alluvial and periglacial deposits, not commonly recognised in this type of setting, occur in the sequence. These include weathered coarse alluvium, sandy channel fills as well as cryoturbated sediments and solifluction deposits, which are positive evidence of a non-glacial environment. The sequence of sediments that represents an emergence cycle has been formalised in a facies model.

Multiple Quaternary erosion and infill cycles in overdeepened basins of the northern Alpine foreland

The cumulative effect of repeated extensive glaciations represents a poorly constrained component in the understanding of landscape evolution in mid-latitude mountain ranges such as the Alps. Timing, extent, and paleo-climatic conditions of these glaciations are generally poorly understood due to the often-fragmentary character of terrestrial Quaternary records. In this context, the sedimentary infills of subglacial basins may serve as important archives to complement the Quaternary stratigraphy over several glacial–interglacial cycles. In this study, sedimentary facies, valley-fill architecture, and luminescence dating are used to describe nine erosional and depositional cycles (Formations A–I) in the Lower Glatt valley, northern Switzerland. These cycles can be related to the ‘Birrfeld’ Glaciation (~ MIS2), the ‘Beringen’ Glaciation (~ MIS6), and up to three earlier Middle Pleistocene glaciations that can be tentatively correlated to the regional glaciation history. Evidence suggests that deep bedrock trough incision and/or partial re-excavation last occurred mainly during the ‘Beringen’ and ‘Habsburg’ Glaciations. Second-order, ‘inlaid’ glacial basins document separate glacier re-advances during the Beringen Glaciation. The arrangement of subglacial basins in the Glatt valley with different sub-parallel or bifurcating bedrock troughs, re-excavated segments, and inlaid basins document changes in the magnitude and the spatial focus of subglacial erosion over time. The Glatt valley may thus serve as a key example for the glacial landscape evolution in many other repeatedly glaciated forelands.

Across the Arid Diagonal: deglaciation of the western Andean Cordillera in southwest Bolivia and northern Chile

Here we review published cosmogenic records of glaciation and deglaciation from the western cordillera of the arid subtropical Andes of northern Chile and southwest Bolivia. Specifically, we examine seven published studies describing exposure ages from moraines and glaciated bedrock spanning the glaciological Arid Diagonal, the region of the dry Andes where there is no clear evidence for glaciation over at least the last global glaciation. We also present new cosmogenic 36Cl exposure ages from two previously undated sets of moraines in the deglaciated region near 22ºS. Taken together, these records indicate that the most extensive regional glaciation occurred ca. 35-45 ka, followed by slow, punctuated retreat through the global last glacial maximum, and rapid retreat after ~15-17 ka. In the vicinity of the large Altiplanic lakes that existed during the late glacial stage, the 15-17 ka moraines overrode the earlier moraines, whereas elsewhere regionally, on both sides of the Arid Diagonal, late glacial wet periods are represented only by less-prominent moraines in more retracted positions.

Amber in sediments of the Baltic Sea and the Curonian and Kaliningrad bays

In the Kaliningrad region, sediments of the Upper Eocene Prussian Formation accommodates the world’s largest explored amber deposits (up to 90% of world reserves). They are also partly tracked on the shelf of the southeastern Baltic region and subjected to bottom erosion, which is particularly intense during storm activity in the sea. Recent alongshore currents transport amber fragments over great distances, resulting in the formation of new (secondary) amber-bearing deposits in Holocene sediments in some places. The paper addresses formation conditions of such deposits. Catastrophic events, such as hydrospheric floods provoked by the regional glaciation, meteorite falls, and earthquakes (tsunamis), are of great significance.

Overdeepened glacial basins as archives for the Quaternary landscape evolution of the Alps

The Alps and the Alpine foreland have been shaped by repeated glaciations during Quaternary glacial-interglacial cycles. Extent, timing and impact on landscape evolution of these glaciations are, however, poorly constrained due to the fragmentary character of terrestrial archives. In this context, the sedimentary infills of subglacially eroded, ‘overdeepened’, basins may serve as important archives to complement the Quaternary stratigraphy over several glacial-interglacial cycles. In this thesis, the infills of deep subglacial basins in the Lower Glatt valley (N Switzerland) are explored to better constrain the Middle- to Late Pleistocene environmental change. Five drill cores gave direct insight into to the up to ~200 m thick valley fill at the study site and allowed for detailed analysis of sedimentary facies, age and architecture of the basin fills. A first focus is set on the sedimentology of coarse-grained diamicts with sorted interbeds overlying bedrock in the trough center, which mark the onset of deposition in many glacial bedrock troughs. Evidence from macro- and microsedimentology suggests that these sediments are emplaced subglacially and reflect deposition, reworking and deformation in response to repeated coupling and decoupling of the ice-bed interface promoted by high basal water pressures. Overlying these subglacial sediments, large volumes of sandy glacio-deltaic, fine-grained glacio-lacustrine and lacustrine sediments document sedimentation during glacier retreat from the basins. On these thick valley fill sequences the applicability and reliability of luminescence dating is investigated in a second step on the basis of experiments with several different luminescence signals, protocols and experiments to assess the signal stability. The valley fill of the Lower Glatt valley is then grouped into nine depositional cycles (Formations A-I), which are related to the Birrfeld Glaciation (~MIS2), the Beringen Glaciation (~MIS6), and up to three earlier Middle Pleistocene glaciations, tentatively correlated to the Hagenholz, Habsburg, and Mohlin Glaciations, according to the regional glaciation history. The complex bedrock geometry and valley fill architecture are shown to be the result of multiple erosion and infilling cycles and reflect the interplay of subglacial erosion, glacial to lacustrine infilling of overdeepened basins, and fluvial down-cutting and aggradation in the non-overdeepened valley fill. Evidence suggests that in the study area deep bedrock incision, and/or partial re-excavation, occurred mainly during the Beringen and Hagenholz Glaciation, while older structures may have existed. Together with the observation of minor, ‘inlaid’ glacial basins, dynamic changes in the magnitude and focus of subglacial erosion over time are documented.

Postglacial relative sea-level changes in northwest Iceland: Evidence from isolation basins, coastal lowlands and raised shorelines

AbstractRelative sea-level (RSL) data provide constraints on land uplift associated with former ice loading and can be used to differentiate between contrasting ice unloading scenarios. Isolation basin, coastal lowland and geomorphological evidence is employed to reconstruct RSL changes in northwest (NW) Iceland, which may have experienced contrasting uplift patterns. Under local (NW) uplift, highest RSL would be expected in central Vestfirðir, whereas highest RSL would be closest to the main ice-loading centre under regional (central Iceland) uplift. Four new RSL records are presented based on 16 sea-level index points and 4 limiting ages from sites principally focussed along a transect away from central Iceland. The new RSL records highlight spatial variability of Holocene RSL changes and provide constraints on deglaciation. There is an increase in marine limit elevation with proximity to the proposed principal ice loading centre in central Iceland. Highest recorded marine limit shorelines are found in Hrútafjörður-Heggstaðanes (southeast), the lowest in Hlöðuvík and Rekavík bak Látrum (north), and at an intermediate elevation in Reykjanes-Laugardalur (central Vestfirðir). Evidence from Breiðavik-Látrar records early rapid deglaciation in Breiðafjörður or a complex interplay of multiple uplift centres. RSL fell rapidly following deglaciation in several locations as a result of the quick response of the Icelandic lithosphere to unloading. The RSL data along the transect show an uplift pattern consistent with extensive regional glaciation emanating from central Iceland, which could have implications for ice sheet configuration and patterns of deglaciation, glacio-isostatic adjustment modelling and the volume of meltwater input into the North Atlantic.

Seismic stratigraphy and glacial cycles in the inland passages of the Magallanes Region of Chile, southernmost South America

We present results of a marine geophysical survey that imaged submarine sedimentary and geomorphic features of the main inland channels of the Magallanes Region of Chile, in southernmost South America. This region holds a remarkable terrestrial and marine record of glacial variations in the closest landmass to Antarctica. We report evidence for grounded ice along the main channels associated with two ice lobes that flowed from Cordillera Darwin, part of the Austral Andes, into Central Estrecho de Magallanes and Seno Almirantazgo. Multibeam data show drumlins and glacial lineations in Whiteside Channel the northern continuation of Seno Almirantazgo, and iceberg plough marks in Central Estrecho de Magallanes. Multichannel seismic data show a complex array of seismic facies, interpreted as representing two main types of sedimentary units: glacimarine sediments, corresponding to glacial periods, and pelagic sediments, corresponding to interglacial periods. We find that there are two interglacial-glacial cycles represented in this marine sedimentary record. Chronologically: 1) the youngest glacial unit corresponds to the last regional glaciation (~31–18ka); 2) these passageways deglaciated with the retreat from regional glacial limit ‘D’ (~17–18ka), and 3) there is no marine sedimentary or morphological evidence that the Magallanes glaciers readvanced into the main passageways during the Antarctic Cold Reversal (~14–13ka). These findings suggest that final deglaciation of southernmost South America was driven by the atmospheric and ocean warming that started ~18ka as recorded in Antarctic ice core records and sea surface temperature proxies offshore the Magallanes Region.

Spatial‑temporal variability of water balance components in the North area of the Zailiisky Alatau Range

Analysis of changes in WB components (precipitation, evaporation, glacier runoff, dynamical water resources) on the Northern slope of the Zailiisky Alatau was performed for the 1946–2005 time divided into two periods: 1946–1975 and 1976–2005. The territory under investigation included basins of the following rivers: Bolshaya Almatinka, Malaya Almatinka, Talgar, Turgen, Issyk, Chemolgan, Kaskelen, Kargalinka, Prohodnaya, and Uzunkargaly. Their total area down to the closing gauge points amounts to 2644 km2. Summarized glacier areas in these basins and annual runoff were equal, respectively, to: 306.6 km2 and 39.05 km3in 1946–1975, and 253.0 km2 and 38.35 km3 in 1975–2005. In 1946–2005, typical features of regional glaciation dynamics were increasing area of the moraine cover on glaciers and reducing area of bare ice that results in decreasing of the glacial runoff volume, all other factors being the same. The method to calculate the WB components consists of the following constituents: model of seasonal runoff from melted snow and ice in the areas of accumulation and ablation of glaciers; complex of formulas to calculate precipitation, air temperature and humidity, intensity of ice melting under the moraine, bare ice and evaporation within the height intervals corresponding to the main types of surfaces on the glaciers. On the basis of our method, we could reconstruct for the 1876–2015 period long‑term series of data on a runoff, separately annual values and sums for the vegetation periods. They can be used for regional scientific and applied analyses of the river stream discharges. The data on runoff in the Malaya Almatinka River basin and observational data on the meteorological station Almaty (Hydrometeorological Observatory) had been quantitatively substantiated as the representative information for modeling and calculation of water resources on the Northern slope of the Zailiisky Alatau Range.

Middle to Late Devensian glaciation of north‐east Scotland: implications for the north‐eastern quadrant of the last British–Irish ice sheet

ABSTRACTWe present a review of over 175 years of research into the Middle to Late Devensian (Weichselian) glaciation of NE Scotland based crucially on both its lithostratigraphic and geomorphic records. The location of the region, and surrounding seabed, makes this unusually detailed record significant for deciphering the former interactions and dynamics of Scottish and Scandinavian ice within the North Sea Basin (NSB), which continue to be controversial. A 12‐stage event stratigraphy is proposed based on a parsimonious interpretation of stratigraphic relationships, till lithology and regional clast fabrics, striae, subglacial bedforms, ice‐marginal features and published geochronometry at critical sites. The record of regional glaciation supports converging evidence that the north‐eastern quadrant of the last British and Irish Ice Sheet reached its maximum spatial extent in the late Middle to early Late Devensian and later re‐expanded following widespread internal glacial reorganizations, marine transgression and partial retreat from the central NSB. Retreat was interrupted by several glacial readvances of limited extent. Field‐captured data help to identify important events that are not clearly resolved from remote sensing alone, particularly regarding growth phases of the last glaciation.

Early Permian climate change in the Falkland Islands

An Early Permian glacial diamictite forms a distinctive unit within the Falkland Islands sedimentary succession and two aspects of its significance have recently been serendipitously enhanced. Fossil discoveries in exotic limestone clasts bear on palaeogeography, whilst a series of mineral‐exploration borehole cores have allowed a detailed study of the sedimentary record of deglaciation that followed deposition of the diamictite. Statistical analysis of reflectance and XRF core‐scanning data has identified likely Milankovitch periodicities and enabled tentative time‐scale modelling. The ‘icehouse to greenhouse’ transition appears to have spanned approximately 1.2 million years, with waning cycles of re‐advance superimposed on overall glacial retreat. The new results play into a long‐debated geological paradox: although the Falkland Islands are now proximal to the South Atlantic coastline of South America, their geology bears an uncanny resemblance to that of the Cape Fold Belt and Karoo Basin in South Africa. This puzzled the geological pioneers, but became readily explicable when first continental drift and then plate tectonics were invoked to reconstruct the break‐up of the Gondwana supercontinent—although the details remain controversial. One of the key stratigraphical correlation levels throughout the major fragments of southern Gondwana—South Africa, South America, Antarctica and Australia—is the glacigenic deposit left behind by the extensive, Late Carboniferous to Early Permian regional glaciation; in the Falkland Islands it is designated the Fitzroy Tillite Formation.

The role of glaciations in the biosphere

Glaciations took place in five long intervals of the geologic history, called glacioeras: Kaapvaal (Late Archean), Huronian (Early Proterozoic), African (Late Proterozoic), Gondwanan (Paleozoic), and unfinished Antarctic (Late Cenozoic). The glacioeras were similar in structure, duration, and dynamics of evolution. They consisted of three to six glacioperiods including several discrete glacio-epochs. The glacioeras lasted ~200 Myr. They started with small regional glaciations, which expanded, reached intercontinental sizes, and then quickly degraded. There were serious differences between the Precambrian and Phanerozoic glacioeras. A series of ecologic crises related to numerous glacial events led first to abiotic and then to biotic factors. Glaciations caused extinction and stagnation of the Earth’s biota, the appearance of bionovations and new biota, and acceleration of evolution processes. Thus, the glacioeras were the turning intervals of the biosphere evolution.

Multiple climate cooling prior to Sturtian glaciations: evidence from chemical index of alteration of sediments in South China.

Investigation of climatic conditions prior to the Sturtian glaciations is critical to understanding the trigger mechanism for the series of Neoproterozoic global glaciations. In this study, we report high-resolution chemical index of alteration (CIA) records in the sediments of South China prior to the Sturtian glaciation (820~720 Ma). Our results showed there occurred multiple climate cooling before the Sturtian glaciations in South China: (1) a series of episodic and possibly global climate cooling periods from ca. 750 Ma to 725 Ma, which also caused some diachronous regional glaciations; (2) a permanent climate cooling period between ca. 800 Ma and 770 Ma, probably contemporaneous to the global “Bitter Springs stage” δ13C negative excursion; (3) a climate cooling period between ca. 815 Ma and 810 Ma. The three stages of climate cooling are also supported by their correspondence to previously reported extremely low δ18O records of igneous/metamorphic minerals from South China. These climate cooling periods also coincide with the magmatism and rifting events in South China. We argue that tectonic movements were the primary control on the climate cooling before the Neoproterozoic global glaciations.