Late Pleistocene Time Research Articles

Environmental change, geomorphic processes and land degradation in tropical highlands

Abstract The international symposium ‘HighLand2006’, held in Mekelle (Ethiopia), from 21 to 25 September 2006, was the second time that Ethiopia could host a major international scientific event on geomorphological processes. HighLand2006 created a forum for those conducting research on the impacts of environmental change on geomorphic processes and land degradation in East African highlands as well as in similar regions around the globe. Discussions of results and exchange of experiences during indoor sessions as well as excursions have resulted in this distinctive set of scientific papers. The two main questions addressed in this special issue, through case studies in tropical mountain areas on all continents are: 1. How have environmental changes impacted the type and intensity of geomorphic processes in tropical mountains since late Pleistocene times? The answer to this question is strongly linked to our knowledge on changes in climate, vegetation cover, human activities, hydrology, hillslope and fluvial processes for such environments. 2. Which factors control the intensity of land degradation, its on-site and off-site impacts in tropical mountains? This question addresses the role of natural and anthropogenic factors in the degradation of the vegetation cover and in controlling the intensity of hydrological processes, soil erosion, landsliding, reservoir sedimentation and flooding. In parallel with this special Catena issue, a number of selected papers on land degradation and its mitigation in tropical highlands are presented in a special issue of Soil & Tillage Research.

Geochronology of Ailuropoda–Stegodon fauna and Gigantopithecus in Guangxi Province, southern China

Pleistocene faunas from south China are difficult to subdivide based on the long temporal ranges of many taxa and a reduced number of genera in comparison to faunas from temperate north China. In south China, the Ailuropoda–Stegodon fauna is a very general one and includes a relatively stable suite of genera that apparently persisted for long periods of time. These attributes have made constraining its time range difficult. Application of electron spin resonance (ESR) dating of tooth enamel constrains the ages well where uranium uptake was minor. Where uranium uptake into teeth was significant, an approach combining ESR and 230Th/ 234U isotopic analysis also yields excellent ages. Previous estimates of early, middle and late Pleistocene time ranges previously determined by biostratigraphic seriation for the Ailuropoda–Stegodon fauna are confirmed in all cases but are made more precise with our approach, including specific time ranges for certain archaic taxa. Absolute dating also yields an extended time range for Gigantopithecus blacki of 1200 to 310 ka.

Morphotectonic control on drainage network evolution in the Perachora Peninsula, Greece

In tectonically active areas drainage systems are often influenced by the type, geometry, and recent activity of regional and local faults. In the Perachora peninsula, eastern Gulf of Corinth (Greece), most drainage networks are influenced by neotectonic processes and eustasy. Two major east–west trending fluvial systems (Perachora and Pissia) in the southwestern part of the peninsula are affected by faults of similar orientation. Detailed geomorphological mapping was performed focusing on knickpoints, gorges, planation and depositional surfaces, alluvial fans and talus cones. Longitudinal river profiles and hypsometric curves of their basins were constructed utilizing GIS technology. The two drainage systems exhibit opposite network asymmetries. The Pissia network is well developed south of the main channel while the Perachora extends to the north. The analysis of the longitudinal profiles of the main stream channels denotes that they exhibit different evolutionary trends. The Pissia stream has a “transverse” drainage crossing the active Loutraki fault, while the Perachora stream has a “parallel” evolution as it has the same orientation as the Loutraki fault. The drainage system of Pissia is much older than the Perachora as a large part of the latter was underwater in Late Pleistocene times. The combination of eustacy and vertical tectonic movements has led to the development of four marine terraces corresponding to previous high sea-level stands during Oxygen Isotope Stages (OIS) 5e, 7e, 9c and 11c. Following the analysis of the longitudinal profiles and the hypsometric curves two depositional surfaces were verified at Perachora village. The first surface at 280–360 m and the second one between 120 and 160 m are probably related to marine terraces 11c and 7e respectively. The development of the present drainage systems of Perachora and Pissia in the Late Quaternary depends mostly on the fault tectonism of the two main offshore fault systems of Xylokastro and Loutraki resulting in the uplift of marine terraces to heights of more than 300 m, but also due to the inland faults (Pissia and Alepochori) which created depositional surfaces and knickpoints. Sea-level changes have played a secondary role in the development of the drainage systems.

Age of Pre-Neoglacial Cirque Moraines in the Central North American Cordillera

In the western mountains of the United States and Canada are pre-Neoglacial cirque moraines that lie up to about 3 km outside Neoglacial moraines. There is considerable uncertainty as to the ages of the outer moraines and whether or not they are age-equivalent from range to range. The variety of assigned radiocarbon ages found in the literature may be partly due to some authors' use of minimum-limiting dates as near-absolute dates, and use of dates that cannot be definitely related to the deposits in question. With one possible exception, all the dated moraines described in the literature could be as old as the type Temple Lake moraine of Wyoming which has a minimum age of about 11,400 yrs BP based on a recently obtained radiocarbon date. Nearly all paleoecological proxy data from the North American Cordillera, generally derived from continuous sedimentary records, suggest that early Holocene climate was warmer than at present. Global circulation models also suggest an early Holocene thermal maximum in the Cordillera, probably due to Milankovitch forcing. For these reasons a proposal gaining popularity in the literature that widespread "Mesoglaciation" occurred in early Holocene time is premature. We hypothesize that most, if not all, of the moraines in question are correlative and date from Late Pleistocene time.

Escaping the heat: range shifts of reef coral taxa in coastal Western Australia

AbstractOne of the most critical challenges facing ecologists today is to understand the changing geographic distribution of species in response to current and predicted global warming. Coastal Western Australia is a natural laboratory in which to assess the effect of climate change on reef coral communities over a temporal scale unavailable to studies conducted solely on modern communities. Reef corals composing Late Pleistocene reef assemblages exposed at five distinct localities along the west Australian coast were censused and the results compared with coral occurrence data published for the modern reefs offshore of each locality. The resulting comparative data set comprises modern and Late Pleistocene reef coral communities occurring over approximately 12° of latitude. For the modern reefs this gradient includes the zone of overlap between the Dampierian and Flindersian Provinces. Modern reef coral communities show a pronounced gradient in coral composition over the latitudinal range encompassed by the study, while the gradient in community composition is not as strong for Pleistocene communities. Tropical‐adapted taxa contracted their ranges north since Late Pleistocene time, emplacing two biogeographic provinces in a region in which a single province had existed previously. Beta diversity values for adjacent communities also reflect this change. Modern reefs show a distinct peak in beta diversity in the middle of the region; the peak is not matched by Pleistocene reefs. Beta diversity is correlated with distance only for comparisons between modern reefs in the north and the fossil assemblages, further supporting change in distribution of the biogeographic provinces in the study area. Coral taxa present in modern communities clearly expanded and contracted their geographic ranges in response to climate change. Those taxa that distinguish Pleistocene from modern reefs are predicted to migrate south in response to future climate change, and potentially persist in ‘temperature refugia’ as tropical reef communities farther north decline.

Initial Occupation of the Pacific Coast of Chile during Late Pleistocene Times

The record of the initial settlement of South America has significant geographical gaps, especially along the Pacific coast. The study of small sites with brief occupation spans can open windows on high‐resolution contexts in which associations and activities are clear. Through the use of a program designed to identify lacustrine Pleistocene environments in which the initial human populations would presumably have settled, Quebrada Santa Julia, a site attesting to human presence dating to 13,000 calibrated years BP, has recently been located on the semiarid coast of Chile. It is the only known Paleoindian site with fluted projectile points in unambiguous association with extinct megafauna on the Andean Pacific coast. It represents a small lakeside camp with a brief occupation span in which multiple activities, including the processing of prey transported from a nearby location, were conducted. The present of extralocal lithic raw materials argues for movements into the interior, as has been suggested for other early settlements in the Andean region. Notwithstanding its proximity to the littoral, the site has not yielded any evidence of the exploitation of marine resources.

Reconnaissance of Prehistoric Sites on the Red Sea Coast of Eritrea, NE Africa

A surface reconnaissance was conducted for prehistoric sites along the Gulf of Zula and the Buri Peninsula, on the Red Sea coast of Eritrea. The sites, found in a wide range of geomorphological Settings, belong mainly to Middle Stone Age, Late Stone Age and Neolithic cultural phases. A few Acheulian bifaces were also documented from eroding surfaces. The different contexts suggest intermittent occupation of the area during Late Pleistocene and Holocene times. Middle Stone Age and Late Stone Age sites in close proximity to the present coastline support a model of coastal adaptation by early humans during the Late Pleistocene. Such coastally-adapted humans are thought to have been source populations for human dispersal into Eurasia across the Bab al-Mandab Strait (southern Red Sea).

KANGAROO MICE (MICRODIPODOPS MEGACEPHALUS) OF THE MONO BASIN: PHYLOGEOGRAPHY OF A PERIPHERAL ISOLATE

Kangaroo mice (Microdipodops) inhabiting the Mono Basin and adjoining valley regions of California and Nevada represent a disjunct distributional isolate and have been considered as a distinct species or, more recently, as 2 subspecies of M. megacephalus. Analysis of patterns of geographic variation in 11 populations in the Mono Basin region shows that kangaroo mice inhabiting the northern portion of this peripheral isolate are relatively large and dark (referred to as M. m. nasutus), and those to the southern end are small and pale (termed M. m. polionotus), and a cline exists between the 2. Inasmuch as several morphological characters are correlated positively with environmental measures (e.g., hind-foot length and climatic severity; pelage color and soil color), it appears that variation in morphology is responding to a selection gradient. Mitochondrial DNA sequence data, together with chromosomal and protein information, reveal that the 2 subspecies are nearly identical genetically. Moreover, molecular phylogeographic analysis reveals that the Mono kangaroo mice belong to the southeastern geographic unit of M. megacephalus (a mean of 1.86% sequence divergence) and are genetically most close to animals from the San Antonio locality (more than 100 km to the east). It is hypothesized that distributional shifts in the geographic range of kangaroo mice in response to climatic fluctuation during the late-Pleistocene and Holocene times resulted in the westward expansion and eventual colonization and isolation of kangaroo mice in the Mono Basin region. Our vicariant biogeographical interpretation suggests a historical route through the Lahontan Trough and the physiographic discontinuity east of Mono Lake (i.e., between the Wassuk Range and the White Mountains) that may serve as a biogeographic model for other basin-dwelling organisms. Lastly, the systematic status of the 2 subspecies is evaluated; a single subspecies, polionotus, is recognized, with nasutus placed in synonymy.

Coastal deformation and great subduction earthquakes, Isla Santa Maria, Chile (37 S)

Research Article| November 01, 2006 Coastal deformation and great subduction earthquakes, Isla Santa María, Chile (37°S) Daniel Melnick; Daniel Melnick 1GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany, and Institut für Geowissenschaften, Universität Potsdam, Postfach 601553, 14415 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Bodo Bookhagen; Bodo Bookhagen 2Department of Geological Sciences, University of California, Santa Barbara, California 93106, USA, and Institut für Geowissenschaften, Universität Potsdam, Postfach 601553, 14415 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Helmut P. Echtler; Helmut P. Echtler 3GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Manfred R. Strecker Manfred R. Strecker 4Institut für Geowissenschaften, Universität Potsdam, Postfach 601553, 14415 Potsdam, Germany Search for other works by this author on: GSW Google Scholar GSA Bulletin (2006) 118 (11-12): 1463–1480. https://doi.org/10.1130/B25865.1 Article history received: 29 Jun 2005 rev-recd: 05 May 2006 accepted: 06 May 2006 first online: 03 Oct 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Daniel Melnick, Bodo Bookhagen, Helmut P. Echtler, Manfred R. Strecker; Coastal deformation and great subduction earthquakes, Isla Santa María, Chile (37°S). GSA Bulletin 2006;; 118 (11-12): 1463–1480. doi: https://doi.org/10.1130/B25865.1 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 Isla Santa María at the active margin of south-central Chile is the result of earthquake-related uplift and deformation in the forearc since at least late Pleistocene time. Field mapping, dating of key depositional horizons, and analysis of seismic-reflection profiles reveal ongoing deformation in this sector of the Chilean forearc. The 30 km2 island is located ∼12 km above the interplate seismogenic zone and 75 km landward of the trench. It is situated near the southern termination of the Concepción earthquake rupture segment, where Charles Darwin measured 3 m of coseismic uplift during a M > 8 megathrust earthquake in 1835. Permanent postearthquake deformation from this earthquake and an earlier event in 1751 is registered by emerged, landward-tilted abrasion surfaces. Uplift at ∼2 m/k.y. and tilting at ∼0.025°/k.y. of the island have been fairly constant throughout the late Quaternary and have resulted in emergence of the island above sea level ∼31 k.y. ago. The island is composed of a late Pleistocene upper, tilted surface with two asymmetric tilt domains, and Holocene lowlands characterized by uplifted and tilted strandlines. Industry offshore seismic-reflection profiles covering an area of ∼1800 km2 and crustal seismicity reveal active reverse-fault cored anticlines surrounding Isla Santa María; the principal fault apparently roots in the plate-interface thrust. These reverse faults in the upper plate result from inversion of late Cretaceous to early Pliocene normal faults and rift structure of the Arauco forearc basin. Positive inversion of these inherited structures started between 3.6 and 2.5 Ma and resulted in continuous shortening rates of ∼0.8 mm/yr. The seismic-reflection profiles show that the asymmetric tilt domains and progressive syntectonic sedimentation are linked to the position of the island in the forelimbs of two converging anticlines, whereas their backlimbs have been removed by cliff retreat. The 2 m uplift contour of the 1835 earthquake is parallel to the strike of active faults and antiforms in the Arauco-Concepción region. The close relation among the asymmetric uplift and tilt of the island, modern deformation patterns, and reverse faults rooted in the plate interface suggests that slip on the plate interface thrust influences, localizes, and segments surface deformation during large interplate earthquakes. Furthermore, the link between positive inversion of pre-existing structures, uplift, and tilt patterns in the forearc emphasizes the importance of inherited structural fabrics in guiding plate-boundary deformation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Yangtse River sediments and erosion rates from source to sink traced with cosmogenic 10Be: Sediments from major rivers

Estimates of regional erosion and sediment mixing from different sources in the Yangtse River system are presented, based on sand samples collected from major tributaries and the trunk stream, at 23 sites between western Sichuan and the Yangtse Delta. Mixing is estimated from concentrations of Mg, Ca, Sr, Ti, Mn and Fe, which are substantially higher in sand from major tributaries in the western Yangtse River catchment than from tributaries in the eastern catchment. Intermediate concentrations occur in sand from the Yangtse Delta, both for modern samples from the surface and for early Holocene samples from drill holes. Mixing ratios indicate that 35 ± 5% of sand in the delta came from eastern sources. A similar result was obtained using cosmogenic 10Be in quartz grains as a tracer of mixing. Regional erosion rate estimated from 10Be in sand grains from high mountain catchments of the western Yangtse River are mostly similar to rates based on sediment gauging but are sometimes higher, and range to over 700 m Ma − 1 , while 10Be measured at upper Yangtse River tributaries on the northeast Tibetan plateau gave rates of 20–30 m Ma − 1 . For the eastern catchments, 10Be measurements from quartz sand and sediment gauging both gave rates of 30–70 m Ma − 1 . Eroding at this rate, the eastern catchments could not supply more than 20% of the sediment in the delta, in contrast with 35% estimated from geochemical fingerprints. The relative input from eastern sources may have been higher in Late Pleistocene times, under a different climatic regime, and reworking of Pleistocene deposits may still be in progress.

Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona

Research Article| March 01, 2006 Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona Wendell Duffield; Wendell Duffield 1Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011, USA Search for other works by this author on: GSW Google Scholar Nancy Riggs; Nancy Riggs 1Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011, USA Search for other works by this author on: GSW Google Scholar Darrell Kaufman; Darrell Kaufman 1Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011, USA Search for other works by this author on: GSW Google Scholar Duane Champion; Duane Champion 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA Search for other works by this author on: GSW Google Scholar Cassandra Fenton; Cassandra Fenton 3GeoForschungsZentrum Potsdam, Telegrafenberg, Haus B, D-14473 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Steven Forman; Steven Forman 4Department of Earth and Environmental Sciences, University of Illinois, Chicago, Illinois 60607, USA Search for other works by this author on: GSW Google Scholar William McIntosh; William McIntosh 5New Mexico Bureau of Mines and Mineral Resources, 801 Leroy Place, Socorro, New Mexico 87801, USA Search for other works by this author on: GSW Google Scholar Richard Hereford; Richard Hereford 6U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, Arizona 86001, USA Search for other works by this author on: GSW Google Scholar Jeffery Plescia; Jeffery Plescia 7Johns Hopkins Applied Physics Lab, 11100 Johns Hopkins Drive, Laurel, Maryland 20723, USA Search for other works by this author on: GSW Google Scholar Michael Ort Michael Ort 8Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2006) 118 (3-4): 421–429. https://doi.org/10.1130/B25814.1 Article history received: 11 Feb 2005 rev-recd: 02 Jun 2005 accepted: 13 Jul 2005 first online: 08 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 Wendell Duffield, Nancy Riggs, Darrell Kaufman, Duane Champion, Cassandra Fenton, Steven Forman, William McIntosh, Richard Hereford, Jeffery Plescia, Michael Ort; Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona. GSA Bulletin 2006;; 118 (3-4): 421–429. doi: https://doi.org/10.1130/B25814.1 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 Grand Falls basalt lava flow in northern Arizona was emplaced in late Pleistocene time. It flowed 10 km from its vent area to the Little Colorado River, where it cascaded into and filled a 65-m-deep canyon to form the Grand Falls lava dam. Lava continued ∼25 km downstream and ∼1 km onto the far rim beyond where the canyon was filled. Subsequent fluvial sedimentation filled the reservoir behind the dam, and eventually the river established a channel along the margin of the lava flow to the site where water falls back into the preeruption canyon.The ca. 150 ka age of the Grand Falls flow provided by whole-rock K-Ar analysis in the 1970s is inconsistent with the preservation of centimeter-scale flow-top features on the surface of the flow and the near absence of physical and chemical weathering on the flow downstream of the falls. The buried Little Colorado River channel and the present-day channel are at nearly the same elevation, indicating that very little, if any, regional downcutting has occurred since emplacement of the flow.Newly applied dating techniques better define the age of the lava dam. Infrared- stimulated luminescence dating of silty mudstone baked by the lava yielded an age of 19.6 ± 1.2 ka. Samples from three noneroded or slightly eroded outcrops at the top of the lava flow yielded 3He cosmogenic ages of 16 ± 1 ka, 17 ± 1 ka, and 20 ± 1 ka. A mean age of 8 ± 19 ka was obtained from averaging four samples using the 40Ar/39Ar step-heating method. Finally, paleomagnetic directions in lava samples from two sites at Grand Falls and one at the vent area are nearly identical and match the curve of magnetic secular variation at ca. 15 ka, 19 ka, 23 ka, and 28 ka. We conclude that the Grand Falls flow was emplaced at ca. 20 ka. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Results of the CERPOLEX/Mammuthus Expeditions on the Taimyr Peninsula, Arctic Siberia, Russian Federation

During a series of expeditions organized by CERPOLEX/Mammuthus to the Taimyr region in northern Siberia several mammoth ( Mammuthus primigenius) carcasses were discovered and subsequently excavated and studied. The oldest specimen is the Arilakh Mammoth (ca. 55,800 BP). Much younger are the Jarkov Mammoth (ca. 20,380 BP) and the Fishhook Mammoth (ca. 20,620 BP), and still much younger are well-preserved Holocene mammoth remains (<10,000 BP). Some paleobotanical data and descriptions of accompanying fauna provide insight into the ecology of the region during Late Pleistocene times. The faunal collapse at the end of the Pleistocene seems to be the result of increasing temperatures, greater humidity, increased snow cover, formation of insulating plant layers, later thawing of the soil, and a lower herbivore density amplifying the climatic effects.

The Use of Caves in Peninsular Thailand in the Late Pleistocene and Early and Middle Holocene

Caves in peninsular Thailand have a complex history of human use ranging from brief campsites to long-term occupation and from locations of industrial activity to landscapes inhabited by spirit forces. In late Pleistocene times, dating from before than 40,000 B.P. to about 11,000 B.P., caves were used only sporadically as temporary campsites, where people built fires, fashioned tools, and consumed the meals of animal (and presumably plant) products. During early Holocene times, dating from before 11,000 B.P. to about 6500 B.P., many caves were occupied for sufficient duration to have built up sizable midden deposits, occasionally over 1 m thick. Some of these deposits also include burials, usually of single randomly placed individuals with few, if any, grave goods. During mid Holocene times, ca. 6500-3500 B.P., some caves were used as burial grounds, with little if any trace of occupation, whereas others were scenes of domestic activity. Mid Holocene and recent times also saw the use of cave walls as media for paintings, with depictions, often crude, of whole or parts of human figures, fish, birds, and land animals.

Holocene sedimentation in the Skagerrak interpreted from chirp sonar and core data

AbstractHigh‐resolution chirp sonar profiling in the northeastern Skagerrak shows acoustically stratified sediments draping a rough‐surfaced substratum. A 32 metre long sediment core retrieved from the survey area encompasses the entire Holocene and latest Pleistocene. The uppermost seismo‐acoustic units in the chirp profiles represent Holocene marine sediments. The lowermost unit is interpreted as ice‐proximal glacial‐marine sediments rapidly deposited during the last deglaciation. The end of ice‐proximal sedimentation is marked by a strong reflector, interpreted to have been formed during latest Pleistocene time as a consequence of rapid ice retreat and drastically lowered sedimentation rate. The subsequent distal glacial‐marine sediments were deposited with initially high sedimentation rates caused by an isostatic rebound‐associated sea‐level fall. Based on correlation between the core and the chirp sonar profiles using measured sediment physical properties and AMS 14C dating, we propose a revised position for the Pleistocene/Holocene boundary in the seismo‐acoustic stratigraphy of the investigated area. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Coupling controls of neotectonism and paleoclimate on the Quaternary sediments of the Yangtze (Changjiang) coast

Attempt has been made to discuss the coupling relation of neotectonism and paleoclimate that have played a critical role in controlling the Quaternary sediment distribution and sedimentary facies evolution on the Yangtze coast. On the basis of petrological analysis, up to six sedimentary cyclicities have been identified in the Quaternary sediment boreholes on the time scale of 0.4–0.5 Ma. The lower sedimentary cyclicities (Pliocene to Early Pleistocene) are characterized largely by thicker gravelly coarse sands, topped by thinner fine silt and silty clay. Gravels are very angular and clayey gravels prevail. Sediments are usually of poor sorting, rich in log fragments and have no microfossils. Bedload as denoted by C-M plot occurs throughout the section. This evidence represents the alluvial fan sedimentation which took place as the basin began to subside. The middle sedimentary cyclicities (often including Early to Middle Pleistocene) consist of basal gravelly sands and clayey silt at the middle and upper sediment sections. Sorting becomes relatively better, and foraminifer appears sporadically. C-M plot reveals the mixture of sediment transport media via bedload, saltation and suspension, representing sedimentation of braided river system at the early stage and subsequently, the sedimentation of meandering river pattern. The upper sedimentary cyclicities (including Late Pleistocene to Holocene) comprise basal gravelly sands (exclusive of the Holocene sediment) and thick fine sand and silty clay on the upper section. Sorting becomes fine and foraminifer appears throughout the sediment section. C-M plot shows that saltation and suspension serve as the main sediment transport media in the sediment section and bedload transport weakens. These evidence the sedimentation of meandering river pattern near coast during Late Pleistocene and Holocene time, when marine transgression invaded into the paleoriver valleys, which often forms drowned-valley facies and shallow marine facies. Of note is the Recent delta facies developed on the top of the cyclicities, and characterized by a large proportion of fine sand and silty clay, and various sedimentary beddings. These phenomena have proved enhanced climate function on sedimentary fades evolution on the basis of previous alluvial fan system, largely affected by tectonic subsidence setting.

The steppe pika Ochotona pusilla in Britain, and a new northerly record

ABSTRACTThe known localities for steppe pika Ochotona pusilla, which occurred in Britain during Late Pleistocene times, are reviewed. A previously misidentified lower jaw, from Helsfell Cave in the Lake District, Cumbria extends the known range of this species in Britain 100 km further north.

Against ecological reductionism: Late Pleistocene hunter-gatherers in the tropical forests of northern South America

Ecological reductionism has been the dominant position in the archaeology of neotropical hunter-gatherers. Traditional conceptions of the early colonists of the Americas stress their role as exploiters of the environment, highly limited by the temporal and spatial structure of resources. Yet, new ideas (and their associated “evidence”) suggest that early hunter-gatherers were already impacting the environment in the neotropics through forest clearing, burning, and cultural selection of key vegetal resources; further, territoriality seems to have developed by Late Pleistocene times, well before it has been admitted. This paper discusses and supports these ideas using recent paleobotanical and archaeological data from tropical forests of northern South America. These arguments are brought to bear in the issue of the early peopling of tropical America.

Structural characteristics of epicentral areas in Central Europe: study case Cheb Basin (Czech Republic)

The earthquake distribution pattern of Central Europe differs systematically from the neighbouring areas of NW and southern Europe regarding the fault plane kinematics. Within a belt between the French Massif Central and the northern part of the Bohemian Massif (1000 km) sinistral faulting along N-S zones dominates on the contrary to the Alps and their foreland with common bookshelf shears. One of the prominent N-S structures is the Regensburg-Leipzig-Rostock Zone (A) with several epicentral areas, where the main seismic center occurs in the northern Cheb Basin (NW Bohemia). The study demonstrates new structural results for the swarm-quake region in NW-Bohemia, especially for the Nový Kostel area in the Cheb Basin. There the N-S-trending newly found Počatky-Plesná zone (PPZ) is identical with the main earthquake line. The PPZ is connected with a mofette line between Hartušov and Bublák with evidence for CO 2 degassing from the subcrustal mantle. The morphologically more prominent Mariánské Lázně fault (MLF) intersects the PPZ obliquely under an acuate angle. In the past the MLF was supposed to be the tectonic structure connected with the epicentral area of Nový Kostel. But evidence from the relocated hypocentres along the PPZ (at 7–12 kms depth) indicate that the MLF is seismically non-active. Asymmetric drainage patterns of the Cheb Basin are caused by fault related movement along Palaeozoic basement faults which initiate a deformation of the cover (Upper Pliocene to Holocene basin filling). The PPZ forms an escarpment in Pliocene and Pleistocene soft rock and is supposingly acting as an earthquake zone since late Pleistocene time. The uppermost Pleistocene of 0.12–0.01 Ma deposited only in front of the fault scarp dates the fault activity. The crossing faults envelope crustal wedges under different local stress conditions. Their intersection line forms a zone beginning at the surface near Nový Kostel, dipping south with increasing depth, probably down to about 12 km. The intersection zone represents a crustal anomaly. There fault movements can be blocked up and peculiar stress condition influence the behaviour of the adjacent crust. An ENE-WNW striking dextral wrench fault was detected which is to expect as kinematic counterpart to the ca. N-S striking sinistral shear zones. Nearly E-W striking fracture segments were formerly only known as remote sensing lineaments or as joint density zones. The ENE shear zone is characterized by a set of compressional m-scale folds and dm-scale faults scattered within a 20 m wide wrench zone. It is built up of different sets of cleavage-like clay plate pattern of microscopical scale. The associated shear planes fit into a Riedel shear system. One characteristic feature are tiny channels of micrometer scale. They have originated after shear plane bending and are the sites of CO 2 mantle degassing.

Post-collisional sediment budget history of the Alps: tectonic versus climatic control

Based on the sediment budget of the Eastern, Swiss and Western Alps since the Oligocene the regional tectonic evolution has been identified as the dominant factor. It is superimposed on the influence of both regional and global climate change and global sea-level change. During late Pliocene and Pleistocene times, climate became the dominant factor because of cyclic glaciations. The early post-collisional history of the Alps is characterized by a doubling of sediment discharge rates around the Rupelian/Chattian boundary. This increase is attributed to isostatic re-adjustment either after large-scale thermal reorganization of the lithosphere related to slab break-off, or to crustal thickening as continental crust became subducted. From Middle Oligocene to Late Miocene times, the overall trend of sediment discharge rates in the entire Alps was modified only during relatively short-lived phases. These are characterized by an increase in Aquitanian (ca. 23–21 Ma) and late Burdigalian times (ca. 18–16.4 Ma), and a decrease in early to middle Burdigalian (21–19 Ma) and Langhian to Serravalian times (16.4–12 Ma). An important, still ongoing period of uplift, reflected by rapidly increasing sediment discharge rates, started in latest Miocene times in the Swiss and Western Alps and affected the Eastern Alps some 2 million years later. The reason for this uplift is not clear, but deep-seated lithospheric processes appear to be likely.

Depositional changes along the Blake–Bahama Outer Ridge deep water transect during marine isotope stages 8 to 10 – links to the Deep Western Boundary Current

ODP sites 1055–1062 recover a bathymetric transect from 1800 to 4800 water depth in the subtropical NW-Atlantic (Carolina Slope, Blake–Bahama Outer Ridge). This sediment drift region is known for high deposition rates (>40 cm/kyr) and offers the excellent opportunity to investigate the history of water mass circulation and chemistry as well as depositional changes during the Quaternary. A late Pleistocene time interval from 250 to 350 kyr (marine isotope stages 8–10) was investigated with centennial- to millennial-scale time resolution. Stable isotope records of benthic foraminifera provide new detailed insights on variations in climate and deep water ventilation. The δ 13C records indicate well ventilated North Atlantic water masses between 2200 and 3000 m water depth during the time interval from stage 9 to interstadial 8.5. During the glacial stages 8.4 and 10.2, however, the decrease in δ 13C reflects an extension of nutrient-rich Antarctic Bottom Water (AABW) up to 2200 m water depth. This is paralleled by a shoaling of the lysocline as indicated by the carbonate records. A comparison between carbonate dissolution proxies points out that the carbonate dissolution at the hemipelagic sites was not only influenced by the different carbonate ion concentration of the water masses (AABW contra North Atlantic Deep Water) but also by the organic carbon flux to the sea floor especially at the shallower sites, whereby the decay of organic matter enhanced carbonate dissolution in the sediments. Additionally the varying depth position and strength of the Deep Western Boundary Current (DWBC) plays an important role on the depositional system along the Blake–Bahama Outer Ridge. Comparisons between current intensities as inferred from grain size analyses, sand, and carbonate contents suggest that high intensities of the DWBC during cold stages caused an erosion of the fine carbonate and an enrichment of the sand fraction at shallower depth. During warm stages the main core of DWBC moved to greater depth and allowed the settling of finer material at shallower depth. Synchronously this led to an increased supply of carbonate and extremely high carbonate concentrations below 3500 m water depth.