Pleistocene Interglacials Research Articles

Estuarine stream piracy: Calvert County, U.S. Atlantic coastal plain

The topography of Maryland's western shore of the Chesapeake Bay shows that five steams now flowing eastward into the bay comprise the pirated (and inverted) headwaters of streams previously flowing westward from a varnished Pliocene upland now occupied by the central Chesapeake. Estuarine shoreline erosion during Pleistocene interglaciations removed the upland, exposing the upper reaches of west-flowing stream valleys. Headward (westward) erosion by east-flowing streams then occurred along existing valleys, facilitated by steep eastward gradients and easily eroded valley-floor sediments. Stream inversion may be more common than previously recognized, since any eroding shoreline causes consumption of seaward-draining watershed and steepening of gradients, thus setting the stage for eventual stream inversion.

Stetson Pit, Dare County, North Carolina: An integrated chronologic, faunal, and floral record of subsurface coastal quaternary sediments

Continuous split spoon samples from a drill hole penetrating 34 m of coastal plain sediments at Stetson Pit in Dare County, North Carolina were taken for lithologic, aminostratigraphic, faunal (ostracodes) and floral (pollen) analyses. Three distinct aminozones are recognized in the subsurface section based upon D-alloisoleucine/L-isoleucine (A/I) values in each of the molluscan species Mulinia lateralis and Mercenaria sp. Ostracode zonations in the subsurface section are based on percentages of 80 thermophilic and cryophilic species (those living today south and north of Cape Hatteras) and the percentages of brackish water species. Five assemblage zones are delineated. Six pollen assemblage zones are also delineated within the subsurface section based upon study of 48 sediment samples. The subsurface record at Stetson Pit is interpreted to represent portions of four interglacials based upon the combined faunal, floral and aminostratigraphic data. The two younger aminozones, with amino acid age estimates of 100,000±20,000 yr (−7.2 to −11.2 m MSL) and 300,000–500,000 yr (−13 to −14.2 m MSL), represent portions of middle/late Pleistocene interglacials. The lower aminozone (−17.4 to −33 m MSL) spans an interval that probably includes at least two interglacials (based upon faunal and floral records) and has an age estimated to be between 800,000 and 1,300,000 yr. Boundaries delineated by faunal, floral, and amino acid methods do not always coincide, due to sampling constraints and phase lags between the different records. One major unconformity (at −17.4 m MSL) in the Stetson Pit section is easily recognized from lithologic characteristics and may represent a hiatus of as much as 800,000 yr. Lithologic changes associated with all other zone boundaries are subtle and would probably not be considered significant in the absence of faunal, floral, or amino acid data.

Dating of Late Pleistocene Interglacial and Interstadial Periods in the United Kingdom from Speleothem Growth Frequency

AbstractThe growth of speleothems is indicative of interglacial and interstadial conditions in the United Kingdom, since their growth is dependent on two factors. First, the occurrence of significant diffuse groundwater recharge and, second, the biogenic production of carbon dioxide in the soil, both are dependent on temperature and water availability. The growth frequency of speleothems is examined using a cumulative distributed error frequency method applied to 341 uncontaminated uranium-series age determinations. The curves derived are shown to be statistically stable, and the ages of the peaks are interpreted as the best estimates of the ages of interglacial and interstadial periods. Ten such periods are recognized during the interval 220,000 to 20,000 yr B.P., considerably more than are currently recognized in the UK pollen- and coleoptera-based Quaternary stratigraphy. Correlations between the speleothem growth frequency peaks and last interglacial (Ipswichian) sites can be made, but correlations with last glacial (Devensian) interstadial sites are limited because of the paucity of dates. The speleothem growth frequency record provides a well-dated terrestrial chronology for the past 140,000 yr B.P., which directly reflects regional palaeoclimatic conditions in Britain, and should prove very useful in unravelling the complex stratigraphy of the Devensian and Ipswichian stages.

Application of palynology in the stratigraphy of quaternary deposits of the U.S.S.R.

The analysis of the data on Pleistocene and Upper Pliocene forest floras in the territory of the U.S.S.R. showed that they can be subdivided into three successive age groups on the basis of the same criterion, the generic composition of geographical groups of dendroflora. Group I is characterized by the presence of American-East Asian and American-Mediterranean-Asian genera: prenemoral flora with similar composition throughout the continent. Group II is characterized by the presence of the only group of genera which is absent in the modern flora of the region: protonemoral flora in Europe and the Far East with American-Mediterranean-Asian genera and quaiboreal in Siberia and Kamchatka with American-Euro-Asian genera. Group III is characterized by the total absence of the genera which are not represented in the modern local flora: nemoral in Europe and the Far East and boreal in Siberia and Kamchatka. The stratigraphic position of the prenemoral flora corresponds to the Lower Pleistocene and the Upper Pliocene. Paleomagnetic evidence of the Ural and Middle Asia indicates that the prenemoral flora existed during the Matuyama epoch. The protonemoral flora in Europe and the Far East corresponds to the Middle Pleistocene interglacials. Nemoral and boreal floras correspond to the Upper Pleistocene and Holocene. Paleomagnetic data on the Kama region, Middle Asia and the Far East indicate that floras of groups II and III existed during the Brunhes epoch. For more detailed subdivision of the deposits other criteria should be used.

Vicende floristiche nei territori delle Alpi Sud-orientali e dell'Adriatico Nord-orientale

Abstract Floristic successions on the territory of the SE-Alps and of the NE-Adriatic region. - Pliocene floras were dominated by a large assortment of trees with prevailing conifers. By the end of the Pliocene broad-leaved trees, especially Faggus, took predominance. Several of these « tertiary » elements disappeared completely by the end of the Pliocene, but some of them, as for instance Tsuga, Carya, Pterocarya, Eucommia repeatedly regained these territories and joined the existing vegetation of the subsequent Pleistocene interglacials. The « tertiary » Fagus too disappeared in the Middle Pleistocene, but made its firs appearance (as a new species?) during the early Wurm interstadials and spread vigorously at the beginning of the Holocene. The Holocene vegetational succession is similar to that of the Middle Europe, North of the Alps. It started from the pioneer Pinus-Betula Forest phase and passed over to the Mixed Oak Forest phase which was followed by a weak and short Corylus phase (phase inversion?...

Pleistocene Vicariance, Montane Islands, and the Evolutionary Divergence of Some Chipmunks (Genus Eutamias)

Distributions of fossil and Recent montane mammals in the American Southwest support a non-equilibrium model. This vicariant explanation, based on vegetational disjunctions during Pleistocene interglacials, is extended in an attempt to predict patterns of evolutionary divergence within a monophyletic lineage. A reconstruction of faunal movements during the Pleistocene based on this explanation suggests at least three complementary hypotheses for evolutionary divergence: 1) endemic forms should arise on the largest mountain ranges; 2) montane satellites of these should share derived forms; and 3) small mountain ranges isolated in both space and time should have been colonized during successive glacial periods by migrating boreal forms. Patterns of bacular morphology within the Eutamias quadrivittatus species complex are used to test the hypotheses. Results of the analysis corroborate the hypotheses, suggesting the need for changes in current thought regarding the arrangement of taxa within this species complex and the origin of altitudinal zonations of species on mountains in the American Southwest. Because the patterns are based on vicariance, patterns of divergence among the chipmunks should characterize divergence in a variety of other montane taxa.

Quaternary glaciation and volcanism, Metolius River area, Oregon

Evidence of three major Quaternary glaciations is recognized in the Metolius River area on the east flank of. the High Cascades. The latest glaciation (Cabot Creek glaciation) is multiple, with evidence of a late readvance (Canyon Creek advance) well displayed in cirques. Post-Altithermal glacial activity is restricted to a twofold late Neoglacial advance on Mount Jefferson and Three-Fingered Jack. Stone-weathering characteristics and soil development are used to differentiate and correlate the drifts throughout the area. The degree of soil development on the drifts suggests that there was a longer period of time between the oldest and intermediate glaciations than between the intermediate and youngest glaciations. Volcanic activity may have been restricted to times of little ice cover, since no evidence of intraglacial volcanism was observed. Tephra and lava flows were erupted during two Pleistocene interglaciations and during Holocene time at scattered locations. The High Cascade platform and probably the stratovolcanoes were largely constructed prior to the earliest recognized glaciation (Abbott Butte glaciation). Information on extent of ice cover during the Cabot Creek glaciation and the Neoglacial advance is sufficiently detailed to reconstruct past glacier margins and estimate former equilibrium-line altitudes (ELA). An accumulation-area ratio of 0.6 ± 0.1 was employed to calculate past ELAs. During the Cabot Creek glaciation, ELAs ranged from about 950 m lower than present at the maximum to 700 to 750 m lower than present for the Canyon Creek advance. Neoglacial ELAs on Mount Jefferson glaciers were lower than present by 200 to 250 m. ELA gradients across the Western Cascades during the Cabot Creek glaciation averaged about 5 m/km, increased to 14 m/km across the High Cascades, and were greater than 38 m/km farther east. This reflects a pattern of precipitation similar to that of the present.

Quaternary landscape development of the Rio Magdalena basin between Neiva and Bogotá (Colombia): A reconstruction based on evidence derived from paleosols and slope deposits

The Quaternary landscape development of part of the middle Magdalena basin is reconstructed from evidence provided by paleosols and slope deposits preserved on glacis surfaces. The paleosols were formed during stable periods with tropical conditions which we have correlated with the Interglacials. The slope deposits were mainly formed during unstable periods with alternating very dry and very wet conditions which we have correlated with the Glacials. If these correlations are correct, it appears that, with the progress of the Quaternary, the (seasonal) variability of the Glacial climates became less pronounced and that of the Interglacial/Postglacial climates more pronounced, leading to a gradually diminishing amplitude of the Quaternary climatic fluctuations. The glacis were formed during periods of pronounced landscape instability (Phase 1, possibly Early or Middle Pleistocene Glacials). Next came a period of landscape stability which left a ferric hydromorphic soil formed in a humid climate (Phase 2, possibly Middle Pleistocene Interglacial(s)). This was followed by an unstable period during which the surfaces of the glacis were somewhat enlarged and covered by coarse slope deposits (Phase 3, presumably penultimate Glacial). After this, part of the area was raised by tectonic movements, streams incised into the glacis surfaces, and stream terraces were formed (Phase 4). During a stable period, plinthic hydromorphic soils and red ferrallitic soils were formed which show the effect of dry seasons (Phase 5, presumably last Interglacial). They were covered with slope deposits formed from shallow mass movements and soil erosion (Phase 6, presumably last Glacial). The sedimentation of volcanic materials began in this period and continued into the first part of the Holocene (Phase 7). Also continuing into the Holocene were (soil) erosion and the deposition of colluvium (Phase 8). During the Holocene, loss of clay due to alternating dry and wet conditions became a more important aspect of soil formation (Phase 9).

Steller's Sea Cow in Pleistocene Interglacial Beach Deposits on Amchitka, Aleutian Islands

Research Article| March 01, 1972 Steller's Sea Cow in Pleistocene Interglacial Beach Deposits on Amchitka, Aleutian Islands L. M GARD, JR.; L. M GARD, JR. U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar G. E LEWIS; G. E LEWIS U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar F. C WHITMORE, JR. F. C WHITMORE, JR. U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1972) 83 (3): 867–870. https://doi.org/10.1130/0016-7606(1972)83[867:SSCIPI]2.0.CO;2 Article history received: 27 Sep 1971 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation L. M GARD, G. E LEWIS, F. C WHITMORE; Steller's Sea Cow in Pleistocene Interglacial Beach Deposits on Amchitka, Aleutian Islands. GSA Bulletin 1972;; 83 (3): 867–870. doi: https://doi.org/10.1130/0016-7606(1972)83[867:SSCIPI]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The first discovery of Steller's Sea Cow (Hydrodamalis) in place in Pleistocene deposits has been made in interglacial beach sand and gravel 35 m above present sea level on Amchitka, Aleutian Islands. Uranium series dating of the bone indicates that it is about 135,000 yrs old. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Pseudanophthalmus of the Appalachian Valley (Coleoptera: Carabidae)

Appalachian Pseudanophthalmus represent relict populations of epigean, endogenous ancestors which colonized caves during Pleistocene interglacials. Ancestral species were probably preadapted to cave life through acquisition of an endogenous habit and their requirement of a cool, moist, microenvironment; they may have undergone partial or total reduction of eyes and pigment before colonizing caves. The imbricated thrust faulting of the valley has produced numerous, comparatively small, discontinuous limestone areas in which cave beetle populations have become extrinsically isolated. Thirty species, in four species groups, are recognized, including thirteen species described as new. The HUBBARDI group (14 spp.) occupies caves in the Shenandoah, Potomac, New, Clinch, and Holston river valleys. The Pusio group (4 spp.) occupies caves in the James, Roanoke, and New river valleys. The HIRSUTUS group (4 spp.) occurs in caves in the drainage basins of the New, Clinch, and Powell rivers. The ENGELHARDTI group (8 spp.) inhabits caves in the drainage basin of the Tennessee River and its tributaries. Cave beetles of the genus Pseudanophthalmus Jeannel are widely distributed in limestone regions of the Appalachian Valley (=Valley and Ridge Province) of Virginia, West Virginia, Tennessee, and Alabama, as well as in the Interior Low Plateaus west of the Allegheny Plateau. George Horn (1868) described Anophthalmus pusio from specimens collected in Erhart's Cave, near Ellet Station, Montgomery Co., Virginia, by E. D. Cope. Sixty years later H. S. Barber (1928) described A. hubbardi from Luray Caverns, Page Co., Virginia, and A. engelhardti from English Cave, near Cumberland Gap, Claiborne Co., Tennessee. In 1928 and 1931, Jeannel transferred all three species to Pseudanophthalmus and described two additional subspecies of P. hubbardi. Most of our knowledge of Appalachian Pseudanophthalmus is the result of extensive studies by J. Manson Valentine (1931, 1932, 1937, 1945, 1948). Jeannel (1949) revised the genus and added new Appalachian species. Since 1949, taxonomic studies of Indiana, Kentucky, and Tennessee Pseudanophthalmus have been published by Krekeler (1958, 1959) and Barr (1959a, 1959b, 1960a, 1962a, 1962b), but none of these was directly concerned with Appalachian Valley species. At the present time there are 79 described species and subspecies of the genus, arrayed in 19 species groups. Four species groups occur in the Appalachian Valley. Twenty-one species and subspecies were previously recognized from the valley. In the present paper 13 species are described as new, one subspecies is relegated to synonymy, three sub1 This investigation was supported by grants from the Penrose Fund (No. 2413) of the American Philosophical Society and from the National Science Foundation (G-18765).

Plateau deposits of the southern Chiltern Hills

Contrary to recent usage but in accordance with Whitaker's original proposal it is suggested that the term Clay-with-flints be restricted to reddish coloured, highly tenacious clay containing flints found immediately overlying Chalk. Other associated heterogeneous flinty and clayey upland deposits usually containing appreciable sand are referred to as Plateau Drift. Definitions of these deposits are given in terms of their macro- and micromorphology, mechanical composition, mineralogy, field distribution and geomorphic relationships. Clay-with-flints appears to have been formed mainly during early Pleistocene interglacials and in late Tertiary times; since the time of the Winter Hill Terrace formation has been insignificant. Clay illuviation and possibly clay synthesis from the weathering products of overlying pervious deposits, in addition to Chalk solution which provides the flints, are considered to be involved in the formation of Clay-with-flints. The formation of Plateau Drift, which is thought to be a more or less crude mixing of Clay-with-flints with Reading Beds and, at particular elevations, with marine and fluviatile gravels and sands, may have resulted from either periglacial or glacial conditions early in the Pleistocene.

Relative Length of Pleistocene Glacial and Interglacial Stages

Relative Length of Pleistocene Glacial and Interglacial Stages