Late Holocene glacial and periglacial evolution in the upper Orco Valley, northwestern Italian Alps

The sediments present in some areas of the Orco Valley provide indications on climatic variations that occurred during the last 6000 years on the southern slopes of the Alps. In particular, distribution and ages of peat layers help define periods and extent of glacial fluctuation in the last 2200 years. Sampling of soils involved in periglacial processes provided a basis for development of a chronological framework of late Holocene environmental change. The data indicate a trend toward cooler climate in the second half of the Holocene. A strong relationship exists between phases of River Po flooding and expansion/retreat phases of the Swiss glaciers: major glacial advances were coeval with periods of intense flooding of the River Po, whereas the phases of glacial retreat coincided with periods of little flooding of the Po. Only in three cases do relationships between glacier activity and floods show weak correlations; two of the cases relate to the warmest periods in approximately the last 2200 years, while the third is the present period. Paleoclimatic evidence from the study region indicates the relatively warm Roman Period between about 2200 and 1900 cal yr BP appears to better represent modern conditions than does the Medieval Warm Period.     

Perspectives on the geoarchaeology of the Lower Mississippi Valley

The impact of Harold N. Fisk's work on the archaeology and geoarchaeology of the Lower Mississippi Valley (LMV) has been monumental. As a result of his landmark publications on the geology of the alluvial valley of the Mississippi River our comprehension of the interplay between geological, geomorphic, and human actions is relatively well developed. However, geologists and archaeologists still need to work together more closely to appreciate and understand the contributions each field has to offer. Examination of the interplay between geologists and archaeologists in the realm of dating and landscape evolution provides the basis for an investigation of the state of geoarchaeology in the LMV today. Integration of research demands an appreciation of scale which must be approached from an historical perspective. Humans have, both in the past and the present, impacted the natural environment of the Mississippi River and its floodplain. Only when this fact is fully appreciated by archaeologists and geologists alike will it be possible to forge a new synthesis of the relationship between the dynamic alluvial valley and its human occupants.     

Groundwater flow modeling of periods with periglacial and glacial climate conditions for the safety assessment of the proposed high-level nuclear waste repository site at Forsmark,Sweden

The impact of periglacial and glacial climate conditions on groundwater flow in fractured crystalline rock is studied by means of groundwater flow modeling of the Forsmark site, which was recently proposed as a repository site for the disposal of spent high-level nuclear fuel in Sweden. The employed model uses a thermal-hydraulically coupled approach for permafrost modeling and discusses changes in groundwater flow implied by the climate conditions found over northern Europe at different times during the last glacial cycle (Weichselian glaciation). It is concluded that discharge of particles released at repository depth occurs very close to the ice-sheet margin in the absence of permafrost. If permafrost is included, the greater part discharges into taliks in the periglacial area. During a glacial cycle, hydraulic gradients at repository depth reach their maximum values when the ice-sheet margin passes over the site; at this time, also, the interface between fresh and saline waters is distorted the most. The combined effect of advances and retreats during several glaciations has not been studied in the present work; however, the results indicate that hydrochemical conditions at depth in the groundwater flow model are almost restored after a single event of ice-sheet advance and retreat.     

Alluvial geoarchaeology of a Middle Archaic Mound complex in the lower Mississippi Valley,U.S.A.

The Nolan site (16MA201), ¹⁴C dated 5200–4800 cal yr B.P. and located in the Tensas Basin of northeastern Louisiana, is the only recorded Middle Archaic mound site in the alluvial valley of the Mississippi River. Alluvial deposition has buried the Nolan site under 3–4 m of Holocene sediment, prohibiting traditional excavation of the site. Because data are unattainable by other means, soil coring and subsequent stratigraphic and sedimentological analyses permit reconstruction of the natural and cultural depositional history of the Nolan site. The sedimentary characteristics of basal deposits within cores suggest the presence of an Arkansas River paleochannel immediately adjacent to the site. Chronostratigraphic data show this channel was no longer active by ca. 5200 cal yr B.P. Contrary to existing models, the Arkansas River Meander Belt 4 and the Mississippi River Meander Belt 4 are not the same age. Microartifact and losson‐ignition analyses of sediment identify natural versus cultural strata and permit the identification of artificial constructions—including four earthen mounds and one earthen ridge—at the Nolan site. Overbank sediments attributed to a mapped Mississippi River Stage 4 meander belt are dated ca. 4800–3800 cal yr B.P. This age is considerably younger than previous estimates and demonstrates the existing chronological models for Mississippi River meander belts must be carefully assessed. Core analyses also reveal flood‐related crevasse splays deposited throughout the Tensas Basin after the occupation of the Nolan site. These deposits serve as relative chronological indicators and aid in stratigraphic assessments of the Nolan site. Reconstruction of the earthworks and their stratigraphic context reveals one of the largest and earliest Middle Archaic mound sites in North America. © 2006 Wiley Periodicals, Inc.     

Last glacial ecology and geoarchaeology of the Central Trans‐Ural area: the Sosva River Upper Palaeolithic Complex,western Siberia

Chlachula, J. & Serikov, Y. B. 2010: Last glacial ecology and geoarchaeology of the Central Trans‐Ural area: the Sosva River Upper Palaeolithic Complex, western Siberia. Boreas, 10.1111/j.1502‐3885.2010.00166.x. ISSN 0300‐9483. Quaternary and geoarchaeology studies from the eastern limits of the Ural Mountains provide multiple lines of evidence of the Palaeolithic peopling of this geographically marginal and still poorly explored territory of western Siberia following the mid‐last glacial (MIS 3) warming. A complex of investigated open‐air localities in the Sosva River basin (the north‐central Trans‐Ural area) at the periphery of the western Siberian Plain, distinguished by very high concentrations of Pleistocene megafaunal remains previously regarded as ‘mammoth cemeteries’, indicate, in conjunction with the associated diagnostic ivory/bone and stone industry, open occupation sites during the Last Glacial (MIS 2). Fossil faunal remains, dominated by mammoth (98%) together with bird and fish species, indicate various methods of exploitation of the Late Pleistocene natural resources and successful behavioural adaptation to the last glacial sub‐polar tundra‐steppe environment. The taphonomy and composition of the well‐preserved skeletal remains from the main occupation sites suggest both active hunting and anthropogenic ‘scavenging’ practices. The contextual geology and the cultural and biotic multi‐proxy records from the Trans‐Ural Upper Palaeolithic Complex provide new insights into the timing and palaeoecological conditions of the Pleistocene human occupation of north‐central Asia.     

Paleorivers and geoarchaeology in the southern Egyptian Sahara

Interpretation of Shuttle Imaging Radar (SIR) images acquired during the November 1981 flight of Columbia led to the idea that a paleodrainage system of regional and perhaps transcontinental proportions crossed southern Egypt and northern Sudan prior to the onset of Quaternary aridity. Three seasons of field investigations in two locales (Wadi Arid and Wadi Safsaf, some 70-80 km apart) near the Sudan border of southern Egypt confirmed initial interpretations of the radar images and produced geologic evidence of fluvial deposition in broad “radar river” valleys (designated RR-1) whose presence is now obscured by eolian sand sheets. Development of an integrated, regional river system probably occurred in the late Paleogene or early Neogene. the river courses eventually were disrupted by tectonism, volcanism, and stream piracy. Their broad valleys were almost fully aggraded long before the middle Pleistocene appearance of man in the area. Some of the large paleovalleys on the radar images contain narrow (0.05-2.0 km wide), braided inset channels (designated RR-2). the RR-2 channels, we believe, represent the last episodes of running water in the valleys during the Quaternary pluvials. In Wadi Arid (the type area for the RR-1 valleys) 36 backhoe trenches and manual excavations yielded Acheulian handaxes, flakes, and cores from nearshore alluvial sediments and surface and shallow subsurface locales. These assemblages are typologically Middle to Late Acheulian and date from ca. 0.15th 0.5 million years ago. the unabraded, unrolled, buried artifacts and their geological contexts indicate that human groups were widely present in a subhumid riparian environment along the edges of the ancient valleys, while these localities were undergoing episodic, local aggradation. Scarce Middle Paleolithic and abundant Neolithic assemblages are widespread along the edges of Wadi Arid and bordering interfluves. In Wadi Safsaf, another broad RR-1 valley, geologic evidence from 20 backhoe excavations demonstrates that an RR-2 channel complex is inset into the alluvial fill in the central part of the valley. No artifacts were found in the alluvium excavated there, but Late Acheulian, Middle Paleolithic, and Neolithic surface assemblages are present nearby. Stratigraphic relations indicate the RR-2 channels are late Pleistocene in age; they were already fully aggraded and their surfaces deflated before an eolian sand sheet of Holocene age was deposited on them. Bir Safsaf, on the northern edge of Wadi Safsaf, was a magnet for Late Acheulian populations, and the paleovalley just south of the bir is bordered with extensive alignments of artifacts, mainly handaxes. Some of these handaxes were found in situ, embedded in alluvial sediments, while others appear to have been exposed on the surface by deflation of the valley fill. The accumulated data support a provisional archaeo-geochronological framework for the last half-million years in the Wadi Arid-Wadi Safsaf area. This framework provides a new geomorphic explanation for the widespread distribution of buried and exposed Middle Acheulian and Late Acheulian assemblages. the interpretation emphasizes the importance of exploring the non-oasis zones for their archaeological and geochronological potential. Although our research has literally only scratched the surface, it demonstrates the potential of radar imaging for defining ancient drainage patterns in arid regions and their associated habitats for human occupation.     

The use of mineral magnetic analyses in the study of glacial diamicts: A pilot study

Mineral magnetic methods of characterising glacial diamicts and their associated sediments are applied to deposits within the Manx Quaternary sequence. The possible advantages of these techniques over more traditional methods of sediment characterisation are outlined, and the results obtained in a pilot study are examined. Results show that both distinctions and similarities exist within the magnetic mineral assemblages of the four diamict units studied. The possible implications of these results for interpreting the Late Quaternary history of the Isle of Man and the future potential of the techniques are briefly discussed.     

A practical guide to the study of glacial sediments

Evans, D. J. A. & Benn, D. I. (eds.) 2004: A Practical Guide to the Study of Glacial Sediments . Edward Arnold, London, 266 pp. ISBN 0–340–75959–3 (pb). GBP 19.99.     

连续与断裂:重新认识下川遗址在中国旧石器文化研究上的意义

2014~2017年,北京师范大学历史学院和山西省考古研究院组织联合考古队,对下川遗址富益河圪梁地点、小白桦圪梁地点、牛路地点、水井背地点、流水腰地点进行了考古发掘。确认下川遗址包含了旧石器中期简单石核-石片文化（大约相当于MIS5）、旧石器晚期早段简单石核-石片文化（4.4~3.0万年）、旧石器晚期中段石叶-细石叶文化（2.7~2.5万年）和旧石器晚期晚段石叶-细石叶文化（1.7~1.6万年）共4个文化发展阶段。经历了3次文化转变,即从旧石器中期向晚期的转变;简单的石核-石片技术向石叶-细石叶技术的转变以及末次冰盛期前后石叶-细石叶技术的变化;在这些转变过程中,并没有表现出完全、持续的连续性;无论在时间上还是技术上,都存在明显的断裂现象;深入研究这些现象,将为中国北方现代人出现和演化提供新的解释。

     

Palaeoeskimo site burial by solifluction: Periglacial geoarchaeology of the tayara site (KbFk‐7), Qikirtaq Island,Nunavik (Canada)

The geoarchaeological study of the Palaeoeskimo Tayara site on Qikirtaq Island (Nunavik) has led to a better understanding of archaeological site formation in the arctic periglacial environment. The surrounding geomorphology (extra‐site) is characterized by fine‐grained, low plastic and leached postglacial glaciomarine sediments that have been reworked by sheet‐like solifluction. This process buried the northern part of the Tayara site with mean annual rates between 1.68 and 2.86 cm/yr over approximately 350 years (1330–980 yr B.P.). The physicochemical and mineralogical properties of the frost‐susceptible glaciomarine sediments may explain their susceptibility to solifluction. This process was probably enhanced by longer thawing periods or warmer/moister summer months that induced active layer thickening or rapid soil thawing. The dates we obtained in the downstream valley show that solifluction occurred during short warm periods in the Late Holocene between ca. 1500 and 1000 yr B.P., after 1000 yr B.P. (or after 500 yr B.P.) and recently (90–60 yr B.P.). Our data provide insights on the site factors and climate factors that govern site burial by solifluction. Solifluction promoted the preservation of the three superposed archaeological levels in the Tayara site; however, the waterlogging of the site related to solifluction also likely caused the subsequent abandonment of the site by the Palaeoeskimo people. © 2008 Wiley Periodicals, Inc.     

Middle to Late Holocene glacial variations, periglacial processes and alluvial sedimentation on the higher Apennine massifs (Italy)

The major climatic variations that have affected the summit slopes of the higher Apennine massifs in the last 6000 yr are shown in alternating layers of organic matter-rich soils and alluvial, glacial and periglacial sediments. The burial of the soils, triggered by environmental-climatic variations, took place in several phases. For the last 3000 yr chronological correlations can be drawn between phases of glacial advance, scree and alluvial sedimentation and development of periglacial features. During some periods, the slopes were covered by vegetation up to 2700 m and beyond, while in other phases the same slopes were subject to glacial advances and periglacial processes, and alluvial sediments were deposited on the high plateaus. Around 5740-5590, 1560-1370 and 1300-970 cal yr B.P., organic matter-rich soils formed on slopes currently subject to periglacial and glacial processes; the mean annual temperature must therefore have been higher than at present. Furthermore, on the basis of the variations in the elevation of the lower limit reached by gelifraction, it can be concluded that the oscillations in the minimum winter temperatures could have ranged between 3.0°C lower (ca. 790-150 cal yr B.P.) and 1.2°C higher (ca. 5740-5590 cal yr B.P.) than present minimum winter temperatures. During the last 3000 yr the cold phases recorded by the Calderone Glacier advance in the Apennines essentially match basically the phases of glacial advance in the Alps.     

A note on the glacial and late glacial history of caithness

It is generally accepted that in the last glaciation Scottish ice from the Moray Firth flowed to the northwest across Caithness depositing shelly drift. Examination of striae along the east coast of Caithness shows that some were formed by ice flowing into and not out of the Moray Firth. It is argued that the flow into the Moray Firth may have occurred in the last glaciation and that the shelly drift may be a relic of an earlier glaciation. The cliffs of Caithness were formed during the Loch Lomond Readvance and have since been raised isostatically and so have been protected from further marine erosion by their own wave-cut platform which can be traced into Orkney where it intersects the present level.     

Late Pleistocene glacial chronology of the Taylor Valley,Antarctica, and the global climate

Carbonate-rich lacustrine and deltaic deposits, containing thin beds of finely laminated carbonates and thick beds of silt, crop out at several sites in the Taylor Valley and have been encountered in cores obtained by the Dry Valley Drilling Project (DVDP). Fragments of the more indurated carbonate beds have widespread occurrence as part of the desert “lag gravel” which covers much of the valley floor. Analysis of the carbonates suggests that they were deposited as algal limestones from waters derived from the East Antarctic Ice Sheet via the Taylor Glacier at times which correspond to the previous three global interglacial periods, as evidenced by the ice volumes deduced from oxygen-isotopic analysis of oceanic cores. The lacustrine carbonates have been found up to 30 km beyond the present terminus of the Taylor Glacier, and up to 100 m above the level of Lake Bonney, into which the Taylor Glacier at present discharges. It is concluded that the Taylor Glacier has advanced during each of the previous three interglaciations, and it is suggested that this has been caused by a thickening of the East Antarctic Ice Sheet during the interglaciations.     

Origin and significance of calcareous concretions within glacial outwash in the Tempo Valley, north-central Ireland

In the Tempo Valley, north-central Ireland, flat-lying calcareous concretions are found within massive sand beds of glaciofluvial outwash which were deposited during the late Weichselian deglacial cycle. ( c . 17 000 14 000 BP). Morphologically, concretions (< 20 cm long. I I cm wide, 3 cm thick) arc bladcd to disc-shaped, lie parallel to sediment bedding planes, and have long axes aligned perpendicular to ice retreat direction. Internally, concretions are massive to framework-supported and were formed as calcareous cements precipitated from solute-rich groundwatcrs. Concretions, related to steep groundwater gradients and vigorous groundwater circulation cells, were formed proglacially at the base of a thin (1.5-2.0 m deep) layer of discontinuous permafrost as meltwater was actively expelled from the retreating ice margin. The presence of a discontinuous permafrost substrate can also help explain regional-scale geomorphic patterns indicating stagnation zone retreat of the Tempo Valley ice mass.     

Variability of laboratory procedures and results in geoarchaeology

Many laboratory techniques are available to geoarchaeologists to determine physical or chemical attributes of sediment or soil samples, and several techniques are often available for analysis of a single attribute. This is illustrated by analyzing duplicate sediment and soil samples from the British Camp Site (Washington) and Lubbock Lake Site (Texas) using two methods for organic carbon content, two methods for organic matter content, and three methods for calcium carbonate content, and several pretreatment procedures for particle-size analysis. These comparisons illustrate that different methods of analysis for the same property of duplicate samples can yield different results. Therefore, when making comparisons with data from other sites or other investigators, the types of laboratory methods used in geoarchaeological analyses are important considerations. Choice of a particular technique will depend on a variety of factors, often conflicting, including the archaeological and geoarchaeological questions being asked, the physical and chemical nature of the samples, and the accuracy, efficiency, and cost of the method.     

Late‐glacial and Holocene river development in the Teleorman Valley on the southern Romanian Plain

This paper reports on a radiocarbon‐dated sequence of alluvial terraces from the Teleorman Valley in the southern Romanian Plain and represents the first Late‐glacial and well‐constrained Holocene alluvial sequence from the lower Danube Valley of southeast Europe. The two earliest and most extensive terraces (T1 and T2) are dissected by large, high‐amplitude palaeochannels, which are dated to ca. 12 800 yr BP and are comparable to large meandering palaeochannels identified from other Late glacial contexts across northern and central Europe. The remaining sequence of alluvial deposits show changes in river activity and accelerated sedimentation around 4900–4800 yr BP, 4000–3800 yr BP, 3300–2800 yr BP, 1000 yr BP and within the past 200 yr. A phase of tributary stream alluvial fan deposition is dated to ca. 2400 yr BP. All these periods of alluvial sedimentation correlate well with episodes of climatic cooling, higher rainfall and enhanced river activity, both in terms of incision and greater lateral mobility as well as increased flood frequency and magnitude identified elsewhere in central, western and northern Europe. Human activity appears to have had little effect on this river environment and significant fine‐grained sedimentation is not noted until ca. 2400 yr BP, approximately 5000 yr after the first neolithic farmers settled the area. Whether this record of river activity truly reflects the impact of prehistoric societies on this catchment will only be elucidated through further, ongoing detailed archaeological research. Copyright © 2003 John Wiley & Sons, Ltd.