Wurm Glaciation Research Articles

ГЕОМОРФОЛОГІЯ, НЕОТЕКТОНІКА ТА ПАЛЕОГЕОГРАФІЯ ТЕРИТОРІЇ ГЕОЛОГІЧНОЇ ПАМ'ЯТКИ "СТАРУНЯ"

A survey of geomorphological and neotectonic features around "The Starunia paleontological site" allows to produce a complete description of paleogeographic conditions and geological age of the Pleistocene mammals. The floodplain terraces I and II and a redevelopment valley have been distinguished on the geomorphological map and a sketch of cross-section of the Velyky Lukavets River valley. The location of fossil fauna (mammoth and rhinoceroses) has been indicated. The prospect of finding new extinct Pleistocene mammals preserved in bitumen and salt has been substantiated. In the late Pliocene, the northeast macro-slope of the Carpathians was dissected by many parallel river valleys transverse to the main Carpathian direction of structures and longitudinal valleys. The rivers took down coarse-grained material from the mountains that formed the high terraces and debris cones (inland delta) of the ancient Dniester valley. The latter was formed at the foot of the Carpathians, in the area of the modern village of Loyeva and the Dniester, then gradually retreated 30–40 km to the northeast and took its present location on the longitude of the town of Halych. Its block mass alluvium formed two ancient terrace plains – Krasna and Loyeva. The climate was subtropical, the type of the present Mediterranean, as evidenced by the red-brown color of the clayey cement of coarse-grained alluvium and cover clays with active migration of iron and manganese. In the early Pleistocene, in the wide swampy valley of the river Lukavets Velykyi, the winding beds of the last stage of river valleys development were quietly meandered. Monotonous dark gray to black marsh accumulations, silt clays, biogenic silts with numerous plant remains accumulated. Landscapes – tundra with dwarf birch, alder, willow etc. The climate was severe, consistent with Wurm (Valdai) glaciation (59–13 thousand years ago). Perhaps just then herds of mammoths and rhinos grazed in the valleys of the Starunia territory and our ancestors Cro-Magnons lived here. The extremely important practical value of Starunia is that further expansion of research and creation of an international ecological-tourist center – the Geopark of the Ice Age will significantly improve the socio-economic status of the village of Starunia, provide the population with new jobs and raise the level of tourism in the Ivano-Frankivsk region. The authors hope that the unique phenomenon of Starunia will be preserved for future generations.

The Carbon Isotope Composition of Organic Matter and the Age of Paleosols from Wurm Glaciations Interstadials to Holocene (Bryansk region, Russia)

Paleosols of Trubchevsk district of the Bryansk region (Russia) lie in landscape with its own characteristic micro-relief, called Trubchevsk Opolye. The radiocarbon data have obtained for two interstadial soils: 16500 ± 230 Ki-17 414, 12930 ± 170 Ki-17 413 years ago. The ratio δ13Corg for underlying sandy pedosediments varies in range -26.5-27.2 %o characterizes relatively humid climate. The most lightweight carbon isotope composition (δ13C = -28.4-29.5 %o) measured for the Holocene second humus horizon, discovered in microdepressions of Trubchevsk opolye and dating (in its upper part) 2180 ± 60 Ki-17 415 BP, 1650±60 Ki-18775. It is characterized by a high content of phosphorus, including its strong accumulation of organic compounds (635.8 mg/kg P2O5).

AN GEOLOGICAL OVERVIEW OF GLACIAL ACCUMULATION AND EROSIONAL OCCURRENCES AT THE VELEBIT AND THE BIOKOVO MTS., CROATIA

Numerous accumulation and erosional forms originating from the activity of small valley glaciers or cirque glaciers occur in the highest mountains in Croatia: Velebit (1757 m) and Biokovo (1762 m). They were produced during the Upper Pleistocene, in the Wurm glacial stage of the Alpine classification.Accumulation forms comprise ground, terminal and recessional moraines, drumlins, eskers, glacial erratics and glaciofluvial and glaciolacustrine sediments. Single ridge eskers are often associated with areas of kame and kettle topography. Among erosional occurrences roche moutonnee (sheepback rocks), U-shaped valleys ranging in size from meso-macro, aretes, hanging valleys, meso-sized cirques, kettles, and striations were noted. In Croatian Dinarides such forms in most cases occur between 900 and 1400 meters altitude. During the early to middle Wurm glacial maximum, the snow line was above 900 m, perhaps even above 1000 m altitude, and sea levels were 120 meters lower than at present day. Considering the features of the present relief, ice cover was probably 200 to 300 m thick. Features of drumlins, eskers and kettles point to warm-based glaciers. The drumlins are small – up to 100 meters long and 50 meters wide, with the most common long axis ranging orientation from 130o – 310o. The near total absence of platy clasts, as well as their stratigraphic affiliation, largely reflects features of source rocks.

Geomorphological features of the archaeological marine area of Sinuessa in Campania, southern Italy

Abstract Submarine surveys carried out since the '90s along the coastland of Sinuessa allowed us to draw up a geomorphological map with archaeological findings. Along the sea bottom, 650 m off and −7 m depth, a Campanian Ignimbrite bedrock was detected: dated ∼39 kyr BP, its position is incompatible with the current sea level. Towards the northern edge of the shoal, a depressed area with 24 cubic elements in concrete was surveyed. These artefacts (pilae) are typical of Roman maritime structures widespread along the southernmost Phlegrean coast. Beachrocks and accessory landforms at the same depth of bedrock suggest that this was emerging and attended by man in Roman times, even for activities related to port facilities. Submerged palaeo-channels, in alignment of current watercourses on the mainland, dissect the shoal. These channels were moulded in subaerial environment during Wurm glaciation, following the tuff deposition, and then were drowned by sea-level rise. The northernmost channel, next to the pilae, likely allowed transit and manoeuvring of Roman ships. The discovery along the seabed of a large stump of lead anchor, hundreds of Roman amphorae and fragments, as well as of a depression of millstone, confirm this finding. Probably the sinuous physiography favored the choice of this site for the docking of Sinuessa, as sheltered from storms.

Geomorphological studies of Jovan Cvijic in Bulgaria

The geomorphologic studies of Jovan Cvijić in Bulgaria are crucial for many Earth scientists from the beginning of the 20th century. Cvijić laid the foundations of the morphotectonic division of the Balkan Peninsula, clarified a number of tectonic and glacial processes and offered proof that there were traces of the Wurm glaciation in Rila Mountain. His findings on the geographical scope of the last glacial period on the Balkan Peninsula are largely based on his research in the Rila and Pirin mountains in Bulgaria. He is the first scientist to define the snow line altitude during the Wurm glacial stage in Balkan Mountains and discover the glacial origin of high mountain lakes there. Many of his theories on relief evolution in the region remain very important to the development of geology and geomorphology in all Balkan countries. In this paper, we provide a review of some publications by Jovan Cvijić that relate to the territory of Bulgaria and analyze the impact of his findings on the work of Bulgarian geologists and geomorphologists.

CHANGES IN THE WORLD OCEAN AVERAGE DEPTH AS A POSSIBLE CAUSE OF THE COMPLETION OF THE WÜRM GLACIATION

The developed hypothesis suggests that the cause of the completion of the Wurm glaciation were the tectonic processes resulting in the decrease of the average depth of the World Ocean and the corresponding increase in its level. The latter turned the better part of the ice sheets in Europe and North America into the ice shelf, that caused their separation from the bed and the massive destruction by waves.A significant extension of the free water surface area led to the rise of the intensity of heat and mass transfer between the oceans and the atmosphere and the growth of its water vapor content. As a result, the greenhouse effect increased and the average temperatures in the troposphere rose as well.A substantial decrease of the cryosphere area in the Northern Hemisphere of the planet also led to the massive reduction of its mean albedo. All this resulted in the climate warming in the regions of our planet not only on the coasts of the oceans but also within the continents, melting glaciers located therein, overflow of the periglacial lakes with melt water and their breakthroughs into the oceans (“glacial flood” by Hancock).

Global Climate Changes and Pantheistic Spiritual Perceptions in Armenian Highland Before and After the Last Wurm Glaciation

Global Climate Changes and Pantheistic Spiritual Perceptions in Armenian Highland Before and After the Last Wurm Glaciation

Genetic homogeneity of the Sedgling Nehalennia speciosa (Odonata: Coenagrionidae) indicates a single Würm glacial refugium and trans‐Palaearctic postglacial expansion

The phylogeographic structures of taiga species often support the hypothesis of East Palaearctic refugia for these taxa, but the phylogeographic structures of northern temperate and southern boreal bog species are still poorly understood. Therefore, we analysed the genetic diversity and differentiation of a stenotopic damselfly, Nehalennia speciosa, across its trans-Palaearctic range by means of sequencing two mitochondrial gene fragments, 16S rRNA-ND1 and cytochrome c oxidase II. Only four single nucleotide polymorphisms were detected over the 1130 sequenced nucleotides. This low genetic diversity and differentiation and thus the lack of phylogeographic structure imply postglacial expansion from a single Wurm Ice Age refugium, most likely located in the Far East of Asia, i.e. Manchurian refugium. From here, the species could have colonized large parts of the Palaearctics, including Europe, during the postglacial.

Deep alpine valleys: examples of geophysical explorations in Austria

Results from geophysical explorations of three deep valleys, selected from different tectonic regimes in the Eastern Alps (Otz-, Oichten-, and Drau Valley), are presented and discussed. Ongoing tectonic deformation may use tectonic structures related to these valleys. However, seismic activity is low there. During the Wurm ice age, the thickness of the ice cover ranged between 300 and 1,500 m above present ground elevation. The geophysical investigations comprised reflection seismology, gravity- and resistivity surveys. The maximum depth down to the erosional base of the valleys varies from ~340 to 700 m. Distinct layer packages of the valley-infill at depths greater than 250 m were termed “old valley-fill”. Geophysical parameters and a comparison with the reflection seismic image of an intermediate layer at the recent Pasterze glacier suggest that the top of the “old valley-fill” represents the glacier bed during the decay of the Wurm glaciation. Deep erosion is not related to high basal shear stress. The confluence of tributary glaciers is apparently not a significant factor for deep erosion in our examples of deep alpine valleys. We conclude that deep erosion may be related to high water pressure at the glacier bed, supported by specific processes of tectonic weakening.

Dates from an important early Late Pleistocene ice advance in the Aare valley, Switzerland

Luminescence dating and sedimentological observations at the Thalgut site, Aare Valley, Switzerland, imply deposition of glaciofluvial sediments and consequently a glacier advance during the earliest Late Pleistocene, just after the Last Interglacial. This glaciation possibly reached the margin of the Alpine foreland, but was probably of much smaller extent than the Wurm glaciation sensu stricto. A significant glacier expansion during the initial Wurmian has already been deduced from pollen analyses, indicating cool but moist climatic conditions. The age of fluvial sediments from the Mattstetten site supports this interpretation of prevailing climatic conditions. The dated sediment apparently represents reworked weathered molasse in a periglacial, but presumably moist, environment during the earliest Late Pleistocene.

Diploid and autotetraploid sexuals and their relationships to apomicts in the Ranunculus cassubicus group: insights from DNA content and isozyme variation

From the predominantly aposporous Ranunculus cassubicus group, a subgroup of the R. auricomus complex, two species with both diploid and tetraploid cytodemes (R. cassubicifolius W. Koch and R. carpaticola Soo) were known. Nine population samples of both species have been analyzed for variation of ploidy levels and isozymes. DNA image analysis showed that three populations of R. cassubicifolius from Bavaria and Salzburg are diploid, two from Lower Austria tetraploid. In R. carpaticola, two populations from Central Slovakia and one from Romania are diploid, one from northern Slovakia is hexaploid. The polyploid populations had somewhat smaller C-values than expected from diploids. Ploidy levels are consistent within populations, contradicting previous hypotheses that cycles of diploid-tetra-ploid-dihaploid apomictic individuals occur in natural populations of goldilocks. Isozyme-allozyme analysis of nine polymorphic loci showed that individual variation and genetic measures of di-ploid and tetraploid populations are equivalent to those of sexual taxa. Multiple allelism and unbalanced gene dosages in tetraploid R. cassubicifolius give evidence for autopolyploidy that is most probably of multiple origin. The observed excess of homozygotes and the high diversity between populations in the diploid populations of R. cassubicifolius are most probably due to geographical isolation of population groups, that might have happened during the Wurm glaciation and might have promoted the separation of autotetraploids in the easternmost part of the distribution range. Genetic distance values analyzed by UPGMA of all sexual populations separated the two taxa and the cytodemes within R. cassubicifolius. Multidimensional scaling of individuals (including the apomicts) based on a presence/absence matrix of alleles confirmed this differentiation with an overlapping zone between R. cassubicifolius and R. carpaticola. The hexaploid R. carpaticola population showed reduced genotypic diversity, an increased number of heterozygotes and fixed heterozygosity as typical for apomictic mode of reproduction. This population shared alleles of both species without any specific ones, multidimensional scaling placed genotypes among R. cassubicifolius. Thus, the hexa-ploid apomicts might have originated from hybrids of R. cassubicifolius and R. carpaticola. In general, evolution of agamic lineages in the R. cassubicus complex might have been facilitated by autopoly-ploids, because they can provide a bridge between the reproductive systems that are otherwise isolated by ploidy levels, and also a starting point for spontaneous origin of apomixis.

Finland's Settling Model Revisited

The author examines the competing hypotheses that have been advanced to explain the origin and migration routes of the Finns, including the suggestion that they formerly inhabited parts of the North European plain immediately to the south of Scandinavia during the latter part of the Wurm glaciation. As the ice retreated northwards at the end of the Fourth or Wurm glaciation, the ancestors of the Finns similarly moved into Finland from a more easterly part of the North European plain, along the eastern rim of the expanding lake which later became the Baltic Sea. Key Words: Finns, Saami, Finno-Ugric languages, Indo-European languages, Upper Paleolithic, Mesolithic, Scandinavia, Baltic Sea, North European archeology, Wurm glaciation. In 1980, 1 included a model for the spread of Mesolithic hunters into deglaciating northern Europe at the end of the Ice Age as a chapter of my PhD thesis. A slightly modified version was later published in an article, A model for the early settlement of Finland (1987). The latter was intended as a provocation to prompt discussion, and that it did (Dolukhanov 1989; Leskinen 1989; Welinder 1989; Nunez 1989); though perhaps not enough. Subsequently, I have updated the subject in lectures and papers on various occasions (e.g. Nunez 1990, 1995; Nunez and Taavitsainen 1992). The present article is, as the heading suggests, a reassessment of this 17 year-old model in the light of old and new information. On the Dates Used There is no longer an excuse not to use calibrated radiocarbon dates in Finnish archeology now that the tree-ring calibration curve extends far back enough to encompass the whole of Finnish prehistory. This work uses tree-ring calibration for conventional radiocarbon dates back to 10,000 bp (ca. 9200 cal BC) and the calibration based inferred atmospheric spline of coral data for conventional dates within 10,000-18,800 bp (ca. 9200-22,000 cal BC). Since this may be confusing to researchers used to other dating systems, the calibrated values for dates between 7500 and 22,000 cal BC will be followed by the corresponding conventional dates labeled bp. To avoid an overlap between calibrated dates and those that fall outside the calibration range, conventional dates beyond 18,800 bp will be adjusted by adding 3,000 years and labelled BC. Thus 22,000 bp will become 23,000 BC. The 3,000 years roughly corresponds to the difference between the last calibratable conventional date and its calibrated value: 18,899 bp and 21,950 cal BC. All calibrated dates used here have been obtained with Stuiver's and Raimer's (1993) program. As was the case in the original model (Nunez 1987), the central calibrated values have been rounded off to the nearest 100 years. The Original Model The original model is rather general, both because when it was created - and even now - our knowledge of the vast territories involved was very patchy and because simple general models are best suited to explain long-term processes over large areas. Like T.H. White's hawk, I tried to look at late glacial Europe from such a height that details became blurred and the general underlying processes discernible. The model was based mainly on the extant paleoenvironmental and archeological data and assumed the following: 1. During the glacial maximum, ca. 23,000 BC - 19,500 cal BC (ca. 22,000-18,000 bp) human groups had successfully adapted to life in the inhabitable zone in the periphery of the ice sheet - the so-called marginal zone. 2. It took at least four millennia for the ice border to retreat from its maximum position across northern Europe to southern Finland. 3. The territories uncovered by the gradually receding ice sheet logically would have become occupied by those human groups living in adjacent areas of the marginal zone. 4. These groups spread metachronically (time-transgressively) with the gradually retreating ice border, reaching southern Finland by 8000 cal BC (ca. …

The European Origin of the Finns and their Relation to the Indo-Europeans

The author traces the history of the prevailing hypothesis which assumes that the ancestors of the present-day Finns and Estonians migrated into their contemporary north European homeland as recently as two thousand years ago. Instead, he suggests that during the latter part of the Wurm glaciation, more than ten thousand years ago, when northern Europe was still covered by ice, they and the Saami (Suomi) were hunters and fishers who occupied an area between the Danube and the Ukraine. They subsequently followed the retreating ice northwards into the eastern Baltic, as that area became habitable. His theory, which is regarded as controversial, would see Finno-Ugrian speakers inhabiting northern Europe before Indo-European speaking farmers displaced them in Northern Germany and western Scandinavia.

Distribution patterns of cavernicolous Collembola in Austria: Proceedings of the Xth international Colloquium on Apterygota, České Budějovice 2000: Apterygota at the Beginning of the Third Millennium

The recent distribution of cave Collembola in Austria is discussed in the light of Quaternary climate oscillations. Four principal patterns are described: (1) widely scattered alpine cave-dwellers which have survived the last glaciation on nunataks; (2) endemic troglobionts within the borders of maximum Wurm glaciation which have endured in their original subterranean habitats; (3) relicts in periglacial refugia at the eastern margin of the Alps; (4) Holocene remigrants from periglacial refugia.

80,000 years ground surface temperature history inferred from the temperature–depth log measured in the superdeep hole SG-4 (the Urals, Russia)

Temperature and thermal conductivity data obtained from the Ural superdeep borehole SG-4 (58°24′N Lat., 59°44′E Long., Middle Urals, Russia) is used to assess ground surface temperature history (GSTH) over the past 80,000 years. GSTH is estimated by solving the one-dimensional heat conduction equation for a homogeneous semi-infinite medium and by comparing the solution with the measured temperatures by means of least square method. The resolution power of paleoclimate signal in the underground temperature field is theoretically studied and a parameter “relative duration” of the climatic event has been introduced. Relative duration is equal to η=( t s −t f)/ t s, where t s and t f are the times before temperature logging of the beginning and end of a climatic event. Only events with η≥0.5 can be resolved from the temperature field. The reconstructed history reveals a number of past climatic events. These include the end of the Wurm glaciation and warming at the beginning of Holocene about 10,000 years ago, Holocene Optimum 4000–6000 years ago, Medieval Warm Period with a culmination about 1000 years ago and Little Ice Age 200–500 years ago. The amplitude of postglacial warming (12–13 K) inferred from the underground temperatures is greater than previously estimated. It is assumed that surface temperature variation amplitude is a function of the combined effects of surface air temperature changes and snow thickness changes. Statistical relations between mean annual soil–air temperature difference and snow cover thickness are proposed.

Le gisement Paléolithique moyen de Meillers (Allier) : un exemple de la variabilité du débitage Discoïde

Abstract Meillers is a vast open-air site, dated to early in the Wurm glaciation, established on top of a Permian chert source. Chert was extracted by prehistoric man and flaked on the site. The prevailing lithic reduction sequence is Discoi'dal, principally unifacial and, to a lesser degree, bifacial. The different types of blanks are not much retouched. The most frequent types of tools are notches and denticulates, then scrapers. Meillers can be interpreted as a site specialised in the production of blanks which are unretouched and, in some cases, exported.

陸橋とヒトと生物の渡来 東シナ海の大陸棚および琉球弧の海底から採取されたほ乳類化石の加速器質量分析法による｀１４´Ｃ年代測定

It is of great interest to know how much the land expanded towards the ocean as the result of the sea-level decrease during the Wurm glacial stage. The existence of land bridges, that plays an important role in transporting human, animals and plants between the Eurasian Continent and the Japanese Islands during the Last Glacial, is still under debate. Geographical and geological studies have been performed to determine the location of shorelines at the Last Glacial maximum. Mammalian fossils collected from the sea bottom of continental shelf and along island arcs can provide decisive evidence of such expanded land areas, if the ages of those mammalian fossils agree with the accepted 14C age (around 18, 000 yr BP) of the Last Glacial maximum.We have conducted 14C dating, with a Tandetron accelerator mass spectrometer (AMS) at Nagoya University, on carbon from collagen fractions extracted from five mammalian fossil samples : (1) a whale bone collected from the Kerama Gap at a depth of 550 m; (2) a deer bone from the continental shelf in the East China Sea, at a depth of 122 m; (3) a water-buffalo horn core from the continental shelf in the East China Sea, at a depth of 100 m; (4) an elephant molar; and (5) a water-buffalo bone from the Penfu Channel between Taiwan and Continental China, at a depth of around 120140 m. Fossil samples, of 2 to 9 g, were demineralized with 1.2 N HCl in a cellulose tube to extract collagen. After demineralization, HCl was completely removed from the tube by dialysis. Then the solution fraction in the tube was separated by centrifuge, and freeze-dried to get a solution-collagen fraction. Solid remains were put in a Pyrex tube with 20 ml of distilled water and heated at 90 t for 10 hours to extract the water soluble gelatin-collagen fraction. Collagen was oxidized, using CuO to produce CO2, in a Vycor tube at 950 °C for an hour. A small aliquot of the CO2 was analyzed for its' stable carbon isotope ratio, δ13 CPDB, using a triplecollector mass spectrometer (MAT-252). To produce graphite, the remaining CO2 was reduced by hydrogen, with an Fe-powder catalyst, in a Vycor tube at 650 °C for several hours. The sample graphite was analyzed for its' 14C/13C ratio, relative to that of an oxalic acid standard (NBS-SRM-4990).To obtain reliable 14C dates for collagen fractions extracted from the fossil samples, the collagen fractions must be preserved from weathering in nature. However, experimental yields of collagen fractions were very low, except for sample no. 2, ranging from 0.01 to 0.11 %, presumably as a result of weathering. CO2 yields from the collagen fractions ranged from 2.2 to 17.4 %, considerably lower than the 4142 % for gelatin collagen extracted from fresh bone samples. This strongly suggests that the samples have suffered from contamination by other organic materials with low carbon contents and not only from weathering. Thus the 14C dates of 14, 640 to 19, 980 yr BP obtained for samples nos. 3, 4, and 5 should be considered unreliable, though these 14C dates are consistent with the age of the Last Glacial maximum. We suspect the 14C dates for samples nos. 3, 4 and 5 are considerably younger than the actual dates, as a result of sample contamination by younger carbon. The CO2 yield from the mixture of both collagen fractions was only 0.12 mg of carbon for sample no.1, being insufficient for 14C dating even with the Tandetron AMS. The yield of gelatin collagen of 4.38 % and the CO2 yield of 32.8-42.7 % for sample no. 2 were reasonably high, enough to give a reliable 14C date, of 25, 750 ± 220 yr BP.

陸橋とヒトと生物の渡来 琉球弧の第四紀古地理

Compilation of seismic reflection profiles, rock sample analyses and manned and non manned diving observations revealed that land bridges, connecting the Ryukyu Arc to the Chinese continent, have appeared in two stages since the late Pliocene. The first stage occurred before the deposition of Pleistocene Ryukyu Limestone and ceased in the early stages of deposition, while the second was apparent during the middle and late stages of the Ryukyu Limestone. The land bridge in the first stage may have appeared between 2.0-1.0 Ma and is well identified by the unconformity between Shimajiri and Ryukyu Groups before the deposition of Ryukyu Limestone. The land bridges may have appeared two or three times in the second stage during or after deposition of Ryukyu Limestone between 0.4-0.02 Ma. The last land bridge may have appeared during the Wurm glacial stage in the late Pleistocene, connecting the Chinese continent through Taiwan, Okinawa and Amami-Oshima to the Kyushu main land. This supports the hypothesis that the Minatogawa Man migrated to Nansei-shoto Islands passing through the land bridge in the Late Pleistocene.

Differentiation of selected species of Belgrandiella and the redefined genus Graziana (Gastropoda: Hydrobiidae)

Abstract Seven species of the genus Belgrandiella A. J. Wagner, 1928 ( sensu lato ), from Austria and Italy are described in detail. The genus Graziana Radoman, 1975, is redefined on a newly discovered character of the stomach, the shield caecum. This is remarkable, since hydrobiid genera are usually defined by characters of the reproductive system. Two species, B. pelerei sp. nov. and G. klagenfurtensis sp. nov. , are new to science. Allozyme electrophoresis of ten populations of these seven species revealed an unusual lack of variability within each population. This is explained as a consequence of the presumed mode of dispersal of these crenobiontic snails, i.e. aerial transport with insects. Genetic distances between conspecific populations and congeneric species fall within the expected range. The only exception is the genetic identity of G. klagenfurtensis and G. lacheineri Kuster, 1853. This identity is probably due to the recent origin of G. klagenfurtensis , whose area was covered with ice during the Wurm glaciation. The high distance values between Belgrandiella and Graziana justify the generic separation based on a character of the digestive system. This is also confirmed through the comparison with three species of the genus Hydrobia Hartmann, 1821, which differs in all systematically relevant aspects from the other two genera.

Würm glaciation of Lake Issyk-Kul area, Tian Shan Mts.: A case study in glacial history of Central Asia

Recent field research and modeling experiments by the authors suggest that Wurm glaciation of Tian Shan Mountains had much larger extent than it was previously believed. Our reconstruction is based upon the following evidence: 1. a till blanket with buried glacier ice occurring on mountain plateaus at altitudes of 3700 to 4000 m asl; 2. trough valleys with U-shaped profiles breaching the border ridges and thus attesting to former outlet glaciers spreading outwards from the plateaus; 3. morphologically young moraines and ice-marginal ramps which mark termini of the outlet glaciers at 1600–1700 m asl (near Lake Issyk-Kul shores) and farther down to 1200 m asl (in Chu River valley); 4. clear evidence of impounding the Chu River by former glaciers and turning Lake Issyk-Kul into an ice-dammed and iceberg-infested basin; 5. radiocarbon dates attesting to the Late Pleistocene age of the whole set of glacial phenomena observed in the area. Our data on past glaciation provide a solution for the so called “paleogeographical puzzle of Lake Issyk-Kul”, in particular they account for the lake-level oscillations (by ice dam formations and destructions), for the origin of Boam Canyon (by impact of lake outbursts), and the deflection of Chu River from Lake Issyk-Kul (by incision of the canyon and build-up of an ice-raft delta near the lake outflow). The Wurm depression of regional snowline was found to be in the range of 1150–1400 m. While today's snowline goes above the plateaus of Tian Shan touching only the higher ridges, the Wurmian snowline dropped well below plateau surfaces making their glacierization inevitable. The same change in snowline/bedrock relationship was characteristic of the interglacial-to-glacial climate switches on the Tibetan Plateau resulting in similar changes of glaciation. The whole history of central Asian glaciations seems to be recorded in the Chinese loess sequences. A finite-element model was used to test two climate scenarios — one with a gradual and another with an abrupt change in snow-line elevation. The model predicted that an equilibrium ice cover would form in 19,000 (first scenario) or 15,000 (second scenario) years of growth. It also yielded ice thicknesses and ice-marginal positions which agreed well with the data of field observations.