L'eau dans le désert du paléodelta de l'Ili (Sud du Lac Balkash, Kazakhstan) : bilan d'une reconnaissance géomorphologique et apport de la télédétection (Waterpresence in the Ili river paleodelta desert (South of the Balkhash Lake) during the upper pleistocene and the holocene : a survey based on satellite and geomorphological data)

2000 ◽  
Vol 77 (1) ◽  
pp. 3-9
Author(s):  
Brigitte Coque ◽  
F. Debaine ◽  
Joëlle Hazemann
Antiquity ◽  
2004 ◽  
Vol 78 (301) ◽  
pp. 579-593 ◽  
Author(s):  
E. Huysecom ◽  
S. Ozainne ◽  
F. Raeli ◽  
A. Ballouche ◽  
M. Rasse ◽  
...  

The area of Ounjougou consists of a series of gullies cut through Upper Pleistocene and Holocene formations on the Dogon Plateau in the Sahel at the south edge of the Sahara Desert. Here the authors have chronicled a stratified sequence of human occupation from the tenth to the second millennium BC, recording natural and anthropogenic strata containing artefacts and micro- and macro- palaeoecological remains, mostly in an excellent state of preservation. They present a first synthesis of the archaeological and environmental sequence for the Holocene period, define five main occupation phases for Ounjougou, and attempt to place them within the context of West African prehistory.


Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 213-218 ◽  
Author(s):  
J C Vogel

Parallel determinations of 14C and ionium dates on a stalagmite from the Cango Caves provide evidence of variations in the 14C content of the atmosphere beyond the range of the California tree-ring sequence. During the Holocene growth period the 230Th dates are compatible with the tree-ring calibrated 14C dates. At 18,000 BP and between 30,000 and 40,000 BP the 14C ages are markedly younger than the 230Th ages, suggesting that the 14C level of the atmosphere was considerably higher at these times. Between the 230Th ages of 35,000 and 29,000 BP the 14C ages remain nearly constant at 29,500 BP, indicating that 14C production must have been drastically reduced during this period. The 14C fluctuation is greater than that predicted by Barbetti (1980) but it may be explained by postulating a substantial increase in the geomagnetic dipole field, for which there is mounting evidence.


1995 ◽  
Author(s):  
L. D. McGinnis ◽  
M. D. Thompson ◽  
G. J. Kuecher ◽  
P. L. Wilkey ◽  
H. R. Isaacson

Author(s):  
António Ferreira Soares

Pliocene and Quaternary Units in the Lower Mondego (Portugal) — The analysis of the relations betweenthe quaternary deposits in the Baixo Mondego, as well as their individualisation from others considered asPliocene, still suffer from insufficient reference marks necessary to guarantee equivalencies. The limitis now considered to be in the concert of the Cruz de Morouços Complex, where the Antanhol Formation(= Barracão Group, Upper Pliocene) and the Espírito Santo Conglomerate, equivalent to the GordosConglomerate (Lower Pleistocene), succeed to each other. From the Pleistocene assemblage andbeside the deposits directly associated to the evolution of Mondego (Ameal-Santo Varão and Tentugal-Gabrielos deposits), the deposits revealing upper littoral environments stand out, as the ArazedeSandstone, the Quiaios Sandstone, others deposits directly related with the Cabo Mondego morphogenesis,the Farol Deposits, fossiliferous and possibly from the Lower to Middle Pleistocene and theMurtinheira Deposits from the Upper Pleistocene. In turn the Condeixa Tuffs, with an accommodationspace of 24 Km2 , show an ordered succession of facies (Conglomerates — Cg; yellow mud — Pa, tuffs— Ta and Tc; grey mud with Lymnea — Pc) and an extended age from the Pleistocene (with Elephasantiquus and Hippopotamus incognitus in the base) possibly around the 400 Ka, to the Holocene (faciesPc with roman archaeological remains).


Author(s):  
Rodolfo José ANGULO ◽  
Maria Cristina De SOUZA

A geologia de superfície da região costeira, entre o Rio Saí-Guaçu e a Baía de São Francisco, litoral norte de Santa Catarina, é constituída por rochas do embasamento cristalino Pré-Cambriano e pela cobertura sedimentar do Cenozóico. O objetivo deste trabalho é apresentar um novo mapa geológico dessa cobertura, na escala 1:50.000, com ênfase na planície costeira. Na área, foram identificadas as seguintes unidades: Fm. Mina Velha do Mioceno Inferior; colúvios, leques aluviais e depósitos fluviais, do Quaternário indiferenciado; terraços costeiros do Pleistoceno Superior (120.000 anos A.P.) e do Holoceno (< 7.000 anos A.P.); planícies paleoestuarinas do Holoceno; dunas, praias e mangues atuais. A distribuição em superfície e subsuperfície e o empilhamento das fácies dos depósitos costeiros permitem compreender alguns aspectos da evolução geológica e paleogeográfica da área durante o Quaternário. A ocorrência de extensos terraços do Pleistoceno e Holoceno, a presença de paleolagunas na retaguarda dos terraços e a ocorrência de sedimentos argilosos lagunares sob os terraços permitem inferir que, durante os ciclos transgressivos regressivos do Pleistoceno superior e Holoceno, existiram na região barreiras transgressivas e regressivas. A extensão das planícies paleoestuarinas indica que durante o máximo transgressivo do Holoceno existiam grandes estuários e lagunas. A morfologia dos cordões litorâneos evidencia que no Holoceno houve a formação de esporões paralelos à costa, que teriam crescido para o norte sob o efeito da deriva litorânea predominante. O crescimento desses esporões teria desviado a desembocadura do Rio Saí-Mirim para o norte. Durante essa migração, o rio erodiu a parte interna desses esporões e, provavelmente, as barreiras transgressivas do Holoceno. GEOLOGICAL MAP OF THE COASTAL PLAIN BETWEEN THE SAÍ-GUAÇU RIVER AND SÃO FRANCISCO BAY, NORTHERN COAST OF THE STATE OF SANTA CATARINA Abstract The studied area is located in the northeastern area of the State of Santa Catarina between 25o57' S and 26o14' S. The surface geology of the area is composed by rocks from the Precambrian basement and from the Cenozoic sedimentary cover. In conventional geological maps, the Cenozoic sedimentary package appears as an undifferentiated unit (e.g. Siga Jr. et al. 1993). Martin et al. (1988) presented the first map of the coastal Quaternary of the State of Santa Catarina, in 1:200,000 scale. Later, Horn Filho (1997) presented a map, in the scale 1:50,000, of the São Francisco do Sul region. The objective of this study is to present a new geological map, in the scale 1:50,000, of the coastal plain between the Saí-Guaçu River and the São Francisco Bay. In the studied area the following Cenozoic age units were identified: Mina Velha Formation, probably of Lower Miocene; colluvium and alluvial fans of undifferentiated Quaternary; fluvial deposits of undifferentiated Quaternary; Upper Pleistocene coastal terraces (120,000 years B.P.); Holocene coastal terraces (< 7,000 years B.P.); Holocene paleoestuarine plains; dunes; beaches and mangroves. The distribution on the surface and subsurface and the layers of facies of the coastal deposits allow an understanding of some aspects of the geological and paleogeographical evolution of the area during the Quaternary. There are extensive Pleistocene and Holocene terraces, the presence of paleolagoons on the terrace backs and also fine lagoon sediments below the terraces makes one infer that during the Upper Pleistocene and Holocene there were transgressive barrier and regressive beach/foredune ridges in the region, similar to those described by Lessa et al. (2000) in the State of Paraná. The extension of the paleoestuarine plains indicates that during the Holocene transgressive maximum there were large estuaries and lagoons. The morphology of the beach/foredune ridges provides evidence that in the Holocene spits parallel to the coast foreland that would have grown northward due to the effect of the dominant littoral drift. The growth of these spits caused the migration of the inlet of Saí-Mirim River more than 6 km northward throughout the last 5,000 years. During this migration the river eroded the internal part of these spits and the Holocene transgressive barriers.


Geobios ◽  
2007 ◽  
Vol 40 (1) ◽  
pp. 75-90 ◽  
Author(s):  
Santiago Fernández ◽  
Noemí Fuentes ◽  
José S. Carrión ◽  
Penélope González-Sampériz ◽  
Encarna Montoya ◽  
...  

Author(s):  
Andriy Yatsyshyn

The geomorphological structure of one of the least explored river valleys of the north-west part of the Fore-Carpathians was discovered. Morphological, morphometric characteristics of the BystrytsiaPidbuzka terraces, the structure features of their deposits’ sections were described. The progress of the glacial morpholithogenetic processes in the north-west part of the Fore-Carpathians was detailed. It was found that the river valley has been actively developing during the Early Pleistocene epoch, when the Galician (the fifth over-floodplain) terrace and four different-age terraces, which have formed the Loyeva level (the sixth over-floodplain terrace) till now, and starosilska terrace, which is hypsographically above the Loyeva level and below the Krasna level, were formed. The benches between the bases of the multiple altitude horizons of alluvium of the identified terraces were mainly disguised by the loess cover that is why actually they were not evident in the terrain. During the Early Pleistocene epoch (the Oka stage), at the time of the deglaciation of the adjacent to the Carpathian Mountains interfluve areas of Stryvihor–Dnister and Dnister–Bystrytsia-Pidbuzka, the glacial meltwater flowed along the river valley to the south. This was illustrated by the fact of the covering of the “warm” alluvium of the channel and flood plain facies by the periglacial alluvium in the section of the Galician terrace of the Bystrytsia-Pidbuzka River. During the deglaciation process of the north-west part of the Dnister valley, the Chukva-Vilshanyk palaeovalley was also invoked. The history of its formation and the structure requires further appraisal up to now. Younger Middle-Upper Pleistocene terraces that were obviously “hidden” in the broad bottom of the river valley morphologically were not clearly demonstrated. According to the morphometric, morphological characteristics they corresponded to the first over-floodplain terrace and BystrytsiaPidbuzka floodplain. However, it has been reliably determined that only its upper 6 meters of the total 24–26-meter of the soft sediments of the mass, which was discovered in the bottom of the BystrytsiaPidbuzka River valley, have accumulated during the Holocene. The formation time of the middle and lower parts was not accurately determined so far. It is possible that it has begun to accumulate during the period of the glacial meltwater discharge, which flowed to the river valley, through both the ChukvaVilshanyk palaeovalley and the Upper-Dnister depression. The surface of the fluvioglacial deposits was covered with the Middle-Upper Pleistocene alluvium, and the section of the mentioned mass was finished by the Holocene alluvium. From the beginning of the Holocene the river valley was surrounded by the ascending tectonic movements, which were especially active on the area that is adjacent to the Carpathians, where their base was outcropped in sections the first over-floodplain terrace and the floodplain. Key words: terrace, Loyeva level, alluvium, loess, glacial meltwater, Upper-Dnister depression, Chukva-Vilshanyk palaeovalley.


2005 ◽  
Vol 38 ◽  
pp. 134
Author(s):  
Α. ΨΙΛΟΒΙΚΟΣ ◽  
Σ. ΜΑΡΓΩΝΗ ◽  
Χ. ΜΟΥΜΟΥ ◽  
Π. ΜΟΥΡΤΖΙΟΣ ◽  
Σ. ΠΕΧΛΙΒΑΝΙΔΟΥ ◽  
...  

In recently dissected ravines of the river Potamia valley on the Mt. Kamvounia (Tranovalto village, Servia, Kozani) occur conical, or column, mushroom forms known in geomorphology as pyramids or earth pillars. Local people call them "Boucharia" meaning chimneys. The relief data reveal a two cycle development. During the first cycle the rocks on the Pliocene surface of the Mt. Kamvounia were eroded. The Pleistocene valleys thus produced gradually filled up with continental deposits mainly red beds. The climatic fluctuations towards the upper Pleistocene affected the weathered rocks of Kamvounia and produced episodic mudflows or debris flows. Various clastic material of the regolith transported during these episodic flows and deposited in the valleys as tongues of limited aerial extend. They consist of heterogenous, chaotic, graded (coarsening up) structures, carrying on their top large boulders of schist or gneiss. Younger red beds deposits covered and protected the episodic mudflow deposits. The investigated case of "Boucharia" consist of a tongue of mudflow deposits 2200 m long, 300 m wide and 2 - 1 1 m thick, on altitudes of 760 m to 670 m, covered with red beds. During the second cycle the Pleistocene regime of deposition was succeeded by the Holocene regime of erosion. The red beds and the enclosed mudflow deposits were eroded by surface flows and the new ravines were formed. The large boulders on the top surface of the mudflow deposits resisted to erosion and protected the underlain materials as cap rocks. In between the material was removed by erosion. So, under every large boulder an earth pillar or pyramid was formed, all along the area of a mudflow tongue. The still active erosional processes continue to remove material from the area, to weaken and gradually destroy the earth pillars all along the sides of the new ravines. The loose mudflow deposits are not able to resist erosion, so the cap rocks usually collapse and the earth pillars are destroyed.The geopyramids, or "Boucharia" in our case, are connected with local myths or superstitions. They can be developed as site views in geoparks for recreation, tourism and education as well.


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