Main Glaciation Research Articles

Upper Visean (Mississippian) coral biostromes during onset of the late Palaeozoic Ice Age: A record from the equatorial eastern Palaeotethys

The late Visean-Serpukhovian is a critical time in reef evolution and climate history, characterized by the gradual collapse of coral reef systems during the onset of the main glaciation phase of the late Palaeozoic Ice Age (LPIA). However, detailed palaeoecological variations of coral reefs during the collapse phase are not well understood. In this study, about one-meter thick coral biostromes are reported from the upper Visean Shangsi Formation in the Yashui section, central Guizhou Province, South China. Coral colonies are primarily in growth position resulting in the classification of autobiostrome and autoparabiostrome. Dominant colonial rugose coral species are Stylostrotion petalaxoidea and Siphonodendron pauciradiale, respectively. The biostromal framework is simple and primarily constructed by bafflestones with slightly positive relief. Diversified dwellers are found between coral skeletons, including abundant foraminifers, crinoids, calcareous algae and brachiopods with less bryozoans, tabulate and solitary rugose corals, gastropods and ostracods. Relative sea-level fluctuations control the growth and demise of the Yashui biostromes, evidenced from changes in both microfacies and biotic assemblages from their underlying to overlying strata. The petalaxoidea biostrome developed in relative deeper water depth than that of the pauciradiale biostrome, between storm wave-base and fair-weather wave-base on a shallow photic open-marine shelf. The pauciradiale biostrome in South China (eastern Palaeotethys) has similar biotic composition, colony preservation and depositional environments to coeval coral biostromes in Ireland (western Palaeotethys). The Yashui coral biostromes formed shortly after the LPIA onset, evidenced in small-scaled eustatic fluctuations and a positive shift in brachiopod oxygen isotopic signatures.

Assessment of atmospheric circulation impacts on the Caspian Sea level and ice regime

The research aimed to assess the influence of atmospheric processes in the Northern Hemi-sphere’s Atlantic-European Sector on the Caspian Sea level based on the data for the days with Wangenheim-Girs atmospheric general circulation forms. The inputs covered the time period from 1900 to 2022. The information on the sea level, precipitation and ice events were harvested from 22 observation points in Kazakhstan and Russia. The statistical and comparative analysis as well as the climate change assessment within the framework of the study pointed to a stable correlation between the sea level and atmospheric circulation; re-vealed certain patterns reflected in precipitation distribution and frequency of moisture defi-cient and excessive years. The research also identified that the climatic changes have al-tered the sea’s ice regime, with the maximum ice thickness decreasing by 13-28 cm depend-ing on a specific water area. In addition to ice thickness variation, the recent decades show an increased frequency of moderate and mild winters, and the shift of the main glaciation dates, i.e. a stable ice cover forming later, the date of fixed maximum ice thickness observed in mid-February, the date of complete ice clearing observed in early-mid March, and the freezing period being shorter.

Global cooling initiated the Middle-Late Mississippian biodiversity crisis

During the Mississippian period, metazoan reefs and other marine faunas gradually recovered from the Late Devonian mass extinctions and reached a peak in the late Visean (~334–332 Ma). Faunal diversity started to decline from the latest Visean (~332–330 Ma) through Serpukhovian (~330–323 Ma), with significant genera/species losses and ecosystem reconstruction. This Middle-Late Mississippian biodiversity crisis (M-LMBC) was thought to have been caused by global cooling associated with the late Paleozoic Ice Age (LPIA), but existing sedimentological and temperature proxy data suggest that the global cooling event—that marks the onset of the main glaciation phase of LPIA—happened either ~4 Myr before or ~ 1–5 Myr after the initial biodiversity decline at ~332 Ma. Here, we report oxygen isotope data of diagenetically screened, well-preserved brachiopod calcite (δ18Ocalcite) from late Visean-Serpukhovian (or Middle-Late Mississippian; ~334–323 Ma) strata in South China where biodiversity data are well documented. The δ18Ocalcite data reveal a ~ 2.0‰ positive shift from −4.6 ± 0.2‰ to −2.7 ± 0.5‰ with an estimated ~4.7–5.5 °C drop in sea surface temperature (SST) during ~332.5–331.5 Ma in the late Visean. This cooling event coincides with fast decline of metazoan reef abundance, followed by decrease of benthic faunal diversity. The δ18Ocalcite data, in combination with calibrated sedimentological and biodiversity data, demonstrate the coupling between late Visean (~332 Ma) onset of the main glaciation phase of the LPIA and initiation of the M-LMBC.

Magnetic parameters and palaeoclimate: A case study of loess deposits of North-East of Iran

Environmental magnetism techniques enable us to reconstruct paleoclimate conditions in some deposition such as losses. The magnetic properties of minerals are used as proxies for environmental changes. For this study, loess/paleosol sequence of Kolet section at Neka, north-east of Iran were magnetically investigated. We applied environmental magnetism methods, to reconstruct paleoclimate changes. We investigated relationship between paleoclimate changes and environmental magnetism proxies like magnetic susceptibility (?) variation. The laboratory techniques indicated the presence of main factor of magnetic property in loess/paleosol sequence, such as magnetite, maghemite and etc. We also estimated magnetically parameters (like SIRM, HIRM and etc.) to confirm concentrations of both aeolian and pedogenic particles versus variations of magnetic susceptibility enhancement. The ? values show prominent peaks for the three well developed soil and paleosol horizons, Recent Soil (S0), Upper Paleosol (S1) and Lower Paleosol (S2); which refer to warmer and wetter conditions. As result, we concluded that the increase/decreasing of magnetic susceptibility is coinciding with palaeosol/loess sequence, and probably with humid/arid conditions. Moreover, variations of magnetic susceptibility versus lithological column of Kolet section enabled us to recognize paleoclimatically periods known as interglacial/glacial cycles. The obtained magnetic data indicate that during over the past 50 ka, there have been at least two glacial/interglacial periods and since last 20 ka, there was no main glaciation occurrence, in the study area.

Pleistocene deposits in the western part of the Holy Cross Mountains

The paper presents characteristics of the Pleistocene sediments in the western part of the Holy Cross Mountains. They are subdivided into four complexes and their stratigraphic setting is referred to the updated scheme for the Pleistocene of Poland. The Preglacial Complex includes fluvial sediments characteristic for its lack of Scandinavian material. Sediments of three main glaciations (Nidanian, Sanian 1 and Sanian 2) within the South Polish Complex, are referred also as the South Polish Glaciations. The oldest of these glaciations (Nidanian) is separated from the middle glaciation (Sanian 1) by sediments of the Podlasian Interglacial, represented by clay at the Kozi Grzbiet Cave that contains faunal remains and record of the Brunhes/Matuyama palaeomagnetic boundary. During the middle (Sanian 1) and youngest glaciation (Sanian 2), the Holy Cross Mountains were almost completely covered by the Scandinavian ice sheet, forming glacial deposits separated by fluvial series of the Ferdynandovian Interglacial. The Middle Polish Complex begins with sediments of the Mazovian Interglacial, represented by a pollen record from the Zakrucze site. They are followed by deposits of periglacial and fluvial origin of the Liwiecian Glaciation, Zbójnian Interglacial, Krznanian Glaciation and Lublinian Interglacial. The following glaciation (Odranian) is represented by the youngest glacial deposits that document presence of the Scandinavian ice-sheet in the westernmost part of the Holy Cross Mountains. The North Polish Complex is composed of a climatic warming (Eemian Interglacial) and cooling (Vistulian Glaciation), and is represented by valley and periglacial deposits. The last cooling of the Pleistocene is recorded in faunal remains in the Raj Cave.

Paleoecology of brachiopod communities during the late Paleozoic ice age in Bolivia (Copacabana Formation, Pennsylvanian–Early Permian)

Studies of modern ecological communities demonstrate that climate change may trigger changes in diversity and taxonomic composition; however, these studies are fundamentally limited to short timescales and therefore cannot demonstrate the full impact of major climate change. Understanding the ecological response of marine invertebrate communities to the Late Paleozoic Ice Age (LPIA), the last complete transition from icehouse to greenhouse, can establish a more complete picture of the climate–faunal relationship. We analyzed brachiopod community structure in Moscovian–Sakmarian (mid-Pennsylvanian to Early Permian) samples spanning the greatest extent of the LPIA, collected from four localities of the Copacabana Formation in Bolivia: Ancoraimes, Yaurichambi, Cuyavi, and Yampupata. Cluster analysis reveals three main groups that appear to coincide with pre-, syn-, and post-glacial times. Genus richness was significantly greater in samples during the Asselian glacial episode; however, the difference may be due to a combination of smaller body size and time averaged mixing of genera from different depths during more rapid glacioeustatic sea level change. Genera present in Bolivia consistently had warm-water affinities, even during the main glaciation, but warm-water taxa increased in abundance over time and the samples became increasingly dominated by characteristically North American genera. Overall mean body size and the size of particular genera were smaller in the Asselian cluster. These size changes likely reflect variations in substrate because marine invertebrates should be larger at cooler temperatures due to oxygen limitation at higher temperatures. The monotonic increase in abundance of warm-water genera and increasingly North American biogeographic affinity imply that community change was most likely the result of the northward drift of Bolivia rather than a response to late Paleozoic glacial–nonglacial cycles. This lack of climate related faunal change was probably a result of Bolivia's mid-latitude location during the late Paleozoic because both the rate of temperature change and its magnitude were likely smaller at lower latitudes, reducing the impact of climate change on marine communities.

Relations between denudation, glaciation, and sediment deposition: implications from the Plio‐Pleistocene Central Alps

AbstractDespite abundant data on the early evolution of the Central Alps, the latest stage exhumation history, potentially related to relief formation, is still poorly constrained. We aim for a better understanding of the relation between glaciation, erosion and sediment deposition. Addressing both topics, we analysed late Pliocene to recent deposits from the Upper Rhine Graben and two modern river sands by apatite fission‐track and (U‐Th‐Sm)/He thermochronology. From the observed age patterns we extracted the sediment provenance and paleo‐erosion history of the Alpine‐derived detritus. Due to their pollen and fossil record, the Rhine Graben deposits also provide information on climatic evolution, so that the erosion history can be related to glacial evolution during the Plio‐Pleistocene. Our data show that Rhine Graben deposits were derived from Variscan basement, Hegau volcanics, Swiss Molasse Basin, and the Central Alps. The relations between glaciation, Alpine erosion, and thermochronological age signals in sedimentary rocks are more complex than assumed. The first Alpine glaciation during the early Pleistocene did not disturb the long‐term exhumational equilibrium of the Alps. Recent findings indicate that main Alpine glaciation occurred at ca. 1 Ma. If true, then main Alpine glaciation was coeval with an apparent decrease of hinterland erosion rates, contrary to the expected trend. We suggest that glaciers effectively sealed the landscape, thus reducing the surface exposed to erosion and shifting the area of main erosion north toward the Molasse basin, causing sediment recycling. At around 0.4 Ma, erosion rates increased again, which seems to be a delayed response to main glaciation. The present‐day erosion regime seems to be dominated by mass‐wasting processes. Generally, glacial erosion rates did not exceed the pre‐glacial long‐term erosion rates of the Central Alps.

Phylogeography of weakfish <i>Cynoscion guatucupa</i> (Perciformes: Sciaenidae) from the southwestern Atlantic

The genetic structure of populations/species was established during the Quaternary glaciations. Over the last 250 ka (Pleistocene), the South American marine biogeographic history recorded three main glaciations: the most extensive one between 140 and 180 ka, a minor one between 60 and 70 ka, and the last glaciation approximately between 15 and 35 ka. With the aim of assessing the pattern of molecular diversity and historical demography of weakfish ( Cynoscion guatucupa ), a 365 bp sequence of the mitochondrial control region was amplified at four coastal sites located in the southwestern Atlantic. Haplotype diversity was high, whereas nucleotide diversity was low and similar at each sample site. AMOVA failed to detect population structure. This lack of differentiation was subsequently observed in the distribution of samples sites in the haplotype network. Fu’s Fs was negative and highly significant while the mismatch analysis yielded a unimodal distribution, indicating a global population expansion. The Bayesian skyline plot revealed a coalescence time of weakfish population at approximately 210 ka, and a very rapid expansion from 180-190 ka, probably caused by a habitat expansion, as these two events coincide in time.

High-resolution stable isotope stratigraphy of Upper Ordovician sequences: Constraints on the timing of bioevents and environmental changes associated with mass extinction and glaciation

The two phases of the Late Ordovician mass extinction are approximately coeval with the periods of rapid climate change associated with the onset and demise of the Gondwanan glaciation. In this paper we argue that the distinctive Late Ordovician carbon isotope profile provides a chronostratigraphic "ruler" against which a sequence of environmental and biotic events may be located. The ruler also allows regional and global high-resolution correlation of successions representing very different environments. Cores from the Upper Ordovician succession of Estonia and Latvia record a large δ 1 3 C c a r b o n a t e excursion (up to 6‰), with a similar profile shape. The consistent relationship between the chemostratigraphy and biostratigraphy in the Baltic region suggests that the isotope profile has a regional chronostratigraphic value. The presence of similar profiles in Nevada, United States, suggests that the excursion is a global chronostratigraphic signal. This interpretation enables a detailed correlation to be made between Upper Ordovician shallow-marine and basinal sequences that have wholly different faunas. Successions in the Baltic area and in Canada that do not display the model profile are interpreted as incomplete. Reinter-pretation of these important successions significantly modifies the global database used to assess the pattern of diversity change during the mass extinction. Key levels of environmental change have been located against the carbon isotope profile. New oxygen isotope data from brachiopod and ostracode calcite set tight limits on the start of the glacial events. Cooling and sea-level fall started at the same stratigraphic level as the start of the carbon isotope excursion. The later rise in sea level and fall in oxygen isotope values record the end of the glaciation. These restrict the duration of the main glaciation to only 1.5 graptolite zones. We propose that models of the carbon cycle should be adapted to be consistent with the temporal relationships between carbon cycling, sea-level fall, and temperature change documented here. The chronostratigraphic "ruler" provided by the carbon isotope profiles is used as a scale to determine the sequence of biotic changes and to allow high-resolution correlation of biotic events at different locations. This approach identifies regional similarities and differences in the patterns of extinction. The main phase of graptolite extinction in the Monitor Range, Nevada, for example, is synchronous with the chitinozoan extinction in the Baltic region, but chitinozoan taxa survive to higher levels in Nevada. The benthic faunas in the Baltic region demonstrate that the main extinction event corresponded with the beginning of the isotope excursion at the start of the Hirnantian-the level at which the marine environment started to change rapidly-but that there were further extinctions of species within the early Hirnantian. The cold adapted Hirnantia fauna did not appear immediately after the extinction in this area. The relationship between the second phase of extinction and the carbon isotope excursion is less clear, but the available data suggest that the extinction coincides with a time of rapid environmental change, but not at the inception of environmental change, as happened in the first phase.

Petrologic and structural controls on geomorphology of prehistoric Tsergo Ri slope failure, Langtang Himal, Nepal

High relief (Δ h up to 2600 m) and spatial orientation of discontinuities, such as leucogranitic intrusions, mylonitic and pseudotachylitic horizons and related ore structures, were the preparatory causal factors for the giant prehistoric Tsergo Ri landslide (High Himalayan Crystalline, Langtang Himal, Nepal). Other controlling factors include overthrusting, detachment faulting, and paleoseismics related to the Main Central Thrust (MCT) and Southern Tibet Detachment System (STDS), neotectonically generated structures, and predesigned form of the scarp (broken crest) and the direction of movement towards the WSW. Coherently displacement of several 10 9 m 3 materials caused frictional fusion. Landslide dynamics and specific morphologic conditions created four different types of sliding surfaces (in chronological sequence): (i) primary—at the basement, (ii) secondary—parallel or subparallel to (i), (iii) tertiary—vertical to (i) and (ii), and (iv) quarternary sliding surfaces—local variety of (iii). (Note: ordinal numeric terms are not in time-stratigraphic sense.) These planes represented the main discontinuities conducting different syn-event stresses in the sliding mass and for further landslide dynamics. Spatial difference and widespread distribution of sliding planes and sets of discontinuities all over the landslide area caused different classes of rock quality, which subsequently determined specific erosional processes within the landslide accumulation area. The subsequent glacial and fluvial erosional processes were controlled by the correlating preexisting lithotectonic patterns, the hyalomylonitic and/or breccious sliding planes and the recent morphologic features or shapes of Tsergo Ri. (i) The SE part is gradationally brecciated to the top and includes Tsergo Ri itself. The residual mass of the bulk has been eroded almost isometrically as far as the primary sliding plane crops out along the intact gneissic basement. Differences in rock quality along a horizon of secondary sliding planes indicate a steplike break in the relief after the last main glaciation. (ii) The earlier-halted NW part still preserved micromountainous shape of compact sliding blocks (Phushung I and II, Kyimoshung), separated by landslide-dynamic-triggered faults (tertiary and quarternary sliding planes). Primary and secondary sliding planes, almost covered by Holocene sediments, produced an insignificant morphology. (iii) The highest brecciated strike–slip fault, generated during collision with the obstacle of Pangshungtramo Peak in the southwest, is the deeply eroded Dranglung Chu valley, which has been kept morphologically active in a major way until recent times. (iv) Except for the collision obstacle of Pangshungtramo Peak with recent semi-active erosion and a small secondary rockslide (block of Tsangbu) north of it, all surrounding parts show typical features of high altitude erosion.

Chapter 21 Neogene-Quaternary history

This is the final historical chapter in this work outlining principal post-Paleogene events. Section 21.1 summarizes the time scale for these events. The evidence for this is mostly in the interpretation of geomorphic features of uplift and denudation with little preservation of onshore sediments until after the main glaciation had ceased its erosive activity. The consequential depositional record is thus mainly submarine until Holocene time, when it could relate to onshore history. Figure 21.1 shows the distribution of Neogene and Quaternary volcanics, hydrothermal zones and areas of recent seismic activity. Many geoscientists are preoccupied with the closing stages of this story and another volume this size.

Bodengeographische Beobachtungen zur pleistozänen und holozänen Vergletscherung des Westlichen Tienshan (Usbekistan)

Abstract. Soil geographic studies were carried out in the Oigaing valley between Ugamsky and Pskemsky range NE of Tashkent (W-Tienshan, Republic of Uzbekistan) with special regard to the Pleistocene and Holocene glaciation. Clear end moraines of the last main glaciation are preserved at the junction of Maidan and Oigaing river at 1500-1600 m a.s.l. They show intensively weathered soils with a depth of more than 80 cm. Similar deposits ol presumably Pleistocene or late glacial origin are also located upvalley at the embouchure of numerous side valleys (Beschtor, Tekesch, Aütor) into the main valley of Oigaing. All side valleys are characterized by late glacial ground and end moraines in 2500-2700 m a.s.l. showing intensively weathered brown colored soils of 30-40 cm depth. Further moraines of Holocene or recent origin are located approach of the recent glaciers which descend to 3000-3200 m. They show shallow, initial soils, and presumably correspond with glacial advances during the so-called "Little Ice Age" with a maximum advance at about 1850 in the Alps, and in the middle Holocene at about 2000 or 4000 a BP. Highly weathered, and rubefied interglacial soils developed from old Quaternary gravel are preserved above high glacial ice marginal grounds of the last main glaciation (>2850 m a.s.l.) in the lower side valley of the Barkrak river. In the upper valley huge drift could be shown above the ice marginal grounds, but without typical forms of morainic deposits. They give evidence for older glaciations with a greater extent compared with the last main glaciation. However, no corresponding moraines are present in the working area.

Soils of the high mountain region of Eastern Nepal: classification, distribution and soil forming processes

Eleven soil profiles of the Mt. Everest region (Dudh Kosi and Beni Khola valley) between 2,700 and 4,900 m a.s.l. were investigated to provide information about soil classification, zonal distribution, and changes in the chemical and mineralogical properties with elevation and climatic conditions. The soils are mainly developed from deposits of the last main glaciation which are predominated by paragneisses. They were classified as Entisols, Inceptisols, and Spodosols according to the U.S. Soil Taxonomy ( Soil Survey Staff, 1990). Detailed chemical and clay mineralogical analyses indicate a strong influence of the elevation, integrating several factors of climatic conditions and bioclimatic zones, on soil types and soil forming processes. Inceptisols predominate in the hill zone and lower tropical mountain zone between 2,000 and 3,000 m a.s.l. They are replaced by Spodosols in the subalpine forest and alpine shrub zone up to 4,500 m. On eroded sites and locations above 4,500 m shallow and stony soils, classified as Entisols, are present. A linear decrease in the intensity of weathering with increasing elevation is shown by the decreasing clay content of the main weathering horizon.

Tunnel-valley formation in northwest Germany—geology, mechanisms of formation and subglacial bed conditions for the Bornhöved tunnel valley

The Bornhöved tunnel valley consists of a relatively broad, elongated depression filled primarily with tills, and a narrow channel in the axial part filled with outwash, glaciolacustrine sediments and tills. The tunnel valley is at least 13 km long, 222 m deep (bottom at 191 m b.s.l.), and extends parallel to the axis of a peripheral sink between two Permian salt diapirs in the substratum. It is suggested that the initiation of the tunnel valley was controlled by a differential response of the bed materials to ice overriding on top of and between the salt structures. The Bornhöved tunnel valley is a polygenetic feature that resulted from different erosional processes throughout all three main glaciations in northern Germany. During the Elsterian Glaciation glaciotectonic squeezing occurred, to be later replaced by subglacial meltwater erosion. During the ice retreat and the Holsteinian Interglacial, the valley was filled with fine-grained glaciolacustrine and marine sediments, which were subsequently removed and redeposited further down-ice as a 200-m-thick glaciotectonic melange by the first Saalian advance. The second Saalian advance caused only minor changes and the tunnel valley was reactivated as a subglacial channel during the Weichselian Glaciation. It is suggested that at the time of the first Weichselian ice advance a large subglacial water reservoir developed in the area of the Baltic Sea basin and caused a rapid, surge-like ice movement. As the ice sheet advanced out of the Baltic Sea basin, drainage of the water reservoir was prevented by the ice toe overriding the permafrost on the Saalian highlands. During the ice retreat, frozen ground was left beyond the ice margin and subglacial meltwater catastrophically drained through the tunnel valley with a discharge roughly estimated at about 3.75 × 10 3 m 3/s. It seems possible that drainage of the subglacial water collector through the Bornhöved tunnel valley and other similar channels south of the Baltic Sea led to increased ice-sheet basal friction, and was one reason for successively smaller extents of the subsequent Weichselian advances. Evidence against pervasively deforming bed materials in the vicinity of the Bornhöved tunnel valley in the Weichselian Glaciation indicates that the valley served as an efficient drainage path for porewater from the subglacial sediments.

An examination of Lynn's evolutionary account of racial differences in intelligence

Lynn hypothesized that the difficulties of survival in cold northern latitudes, like the Eurasian niche, necessitated increased intelligence and that is why Negroid populations relative to Caucasoid and Mongoloid populations had a lower IQ scores. But, the Amerindians, who are Mongoloids, have also a lower one. So, Lynn argued that the Amerindians are the descendants of an archaic Mongoloid population that crossed the Bering Land Bridge before the main Wurm glaciation. But the skeletal, dental, archaelogical, linguistic evidences fail to support this hypothesis. Disease and war were dysgenic selective forces affecting the current IQ score of Amerindians.

A new correlation of the glacial moraines in the Southern Apennines, Italy

Analysis of Late Pleistocene moraines in the Southern Apennines, in Southern Italy, suggests a possible correlation with the sequence in other Italian regions, but correlations with other parts of Europe remain uncertain. The lowest moraines, consisting of complex loops, recognized on the highest peaks in the Southern Apennines, are attributable to the maximum of the last main glaciation. With the subsequent rise in the snow line, the glaciers retreated to new limits marked by two further stadial moraines, the Oldest and Older Dryas respectively, which, according to Federici (1979), can be referred to the first and second Apenninic Stages. The highest moraine loop, which is present only on the Pollino Group, may date from the Lisens stage of the Younger Dryas.

The physical geography and geology of the estuary and Firth of Forth, Scotland

SynopsisThe Upper Palaeozoic bedrock, which is of sedimentary and volcanic origin, is briefly described. The origin of the Forth as a series of depressions in the bedrock surface probably owes much to erosion of a pre-existing Tertiary landscape during phases of Quaternary glaciation. The late Quaternary history of the area is described, relating the distribution of the sediments deposited in the Forth to climatic events and changes in relative sea-level. Since the acme of the last main glaciation about 20,000 years ago, late Devensian marine and estuarine sediments have been deposited on the underlying glacial till sheet at altitudes ranging from more than 120 m below O.D. to at least 46 m above O.D. Similarly, raised and buried beaches and their deposits occur at altitudes from 40 m above O.D. down to around 10 m below O.D. in the estuary. During the Flandrian, sea-level has fluctuated, reaching its maximum (about 11 to 15 m above O.D.) about 6500 years ago. The typical deposit of this period is the carse clay which forms a series of extensive, fertile raised mudflats around the estuary. The calcareous marine faunas of the carse clay and older deposits are outlined.

Periglacial nivation cirques and local glaciations in the rock canyons of Söderåsen, Scania, Sweden. A discussion and new interpretation

Rapp, Anders: Periglacial nivation cirques and local glaciations in the rock canyons of Soderasen, Scania, Sweden. A discussion and new interpretation. Geografisk Tidsskrift 82: 95–99, Copenhagen, October 15, 1982. Present opinions about the genesis of the rock canyons OdensjOn, Skaralid and Klova Hallar of Soderasen, Sweden are reviewed, and a new theory is presented. It is proposed, that during periglacial tundra periods large amounts of drifting snow collected in valleys of north-south directions. Small glaciers were created, which caused local overdeepening and removal of loose material. These processes were active in tundra periods before and after the main Quaternary glaciations. SUMMARY Odensjon, Skaralid and Klova Hallar are three valleys of canyon type, deeply cut (60–100 m) into the horst block of Soderasen, of fractured Precambrian gneiss rock. It has been shown by other authors that the cold periods after the Weichselian deglaciation were characterized by permafrost and ice wedges on sandy pla...

Weichselian chronostratigraphy and correlations

The glacial history of the Fennoscandian ice cap beyond some 20,000 years B.P. is fairly poorly known because of the absence of a reliable dating control. The Eemian Interglacial of Europe is not dated at all. The Weichselian Glaciation seems to be characterized by three main glaciation maxima separated by two main interstadial periods (of quite different conditions). The Grande Pile continuous lake sequence offers a uniquely detailed paleoclimatic and paleomagnetic record of the last 130,000 years. There are obvious correlations between the Grande Pile record, the Dutch palynological records and the Fennoscandian glacial records.

The Gipping Till: a reappraisal of East Anglian glacial stratigraphy

The proposed interpretation of Pleistocene stratigraphy, which results from recent 6-inch geological surveys in the Chelmsford and Norwich areas is at variance with generally accepted correlations relating to the drift deposits of East Anglia. The evidence for the existence of the Gipping Till and its associated glaciation is critically examined. It is concluded that widespread chalky boulder clay was formed during only one glacial episode. It is also suggested that the Hoxnian and Ipswichian deposits in East Anglia are closer in time than has been thought hitherto, and that the main glaciation of East Anglia is the penultimate (Wolstonian).