نتایج جستجو برای: holocene

تعداد نتایج: 8437  

2015
M. Väliranta J. S. Salonen M. Heikkilä L. Amon K. Helmens A. Klimaschewski P. Kuhry S. Kultti A. Poska S. Shala S. Veski H. H. Birks

Holocene summer temperature reconstructions from northern Europe based on sedimentary pollen records suggest an onset of peak summer warmth around 9,000 years ago. However, pollen-based temperature reconstructions are largely driven by changes in the proportions of tree taxa, and thus the early-Holocene warming signal may be delayed due to the geographical disequilibrium between climate and tre...

2008
Fahu Chen Zicheng Yu Meilin Yang Emi Ito Sumin Wang David B. Madsen Xiaozhong Huang Yan Zhao Tomonori Sato H. John B. Birks Ian Boomer Jianhui Chen Chengbang An Bernd Wünnemann

We synthesize palaeoclimate records from the mid-latitude arid Asian region dominated today by the Westerlies (‘‘arid central Asia’’ (ACA)) to evaluate spatial and temporal patterns of moisture changes during the Holocene. Sediment records from 11 lakes with reliable chronologies and robust proxies were selected to reconstruct moisture histories based on a five-class ordinal wetness index with ...

2009
Lewis A. Owen

The timing and extent of latest Pleistocene and Holocene alpine glacier fluctuations in the Himalaya and Tibet are poorly defined due to the logistical and political inaccessibility of the region, and the general lack of modern studies of the glacial successions. Nevertheless, renewed interest in the region and the aid of newly developing numerical dating techniques have provided new insights i...

Journal: :پژوهش های جغرافیای طبیعی 0
داود مختاری

in recent years there has been studies concerning the investigation of macro-scale geomorphic proxies of quaternary climatic changes in the study area. without detail analysis of slope geomorphic features, there can be little progress on expanding the knowledge of past slope development in the northwestern iran high mountain environments. consequently, the information pertaining to these quater...

2005
Jason P. Briner Neal Michelutti Donna R. Francis Gifford H. Miller Yarrow Axford Matthew J. Wooller Alexander P. Wolfe

Reconstructions of past environmental changes are critical for understanding the natural variability of Earth’s climate system and for providing a context for present and future global change. Radiocarbon-dated lake sediments from Lake CF3, northeastern Baffin Island, Arctic Canada, are used to reconstruct past environmental conditions over the last 11,200 years. Numerous proxies, including chi...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2010
Miriam C Jones Zicheng Yu

Northern peatlands represent one of the largest biospheric carbon (C) reservoirs; however, the role of peatlands in the global carbon cycle remains intensely debated, owing in part to the paucity of detailed regional datasets and the complexity of the role of climate, ecosystem processes, and environmental factors in controlling peatland C dynamics. Here we used detailed C accumulation data fro...

2016
Jessie Hughes Brian Meyer Daniel Deocampo Katie Price Sarah Ross

A detailed record of the Late Holocene sea level rise and landscape evolution that has taken place on the Georgia coast is contained within the sedimentary stratigraphy of its salt marsh depositional basins. Global relative sea level (RSL) has risen during the Late Holocene, and the rate of rise has accelerated during the Anthropocene. Jones Narrows marsh stratigraphy and radiocarbon analysis i...

2012
Harvey M. Kelsey Brian L. Sherrod Richard J. Blakely Ralph A. Haugerud

[1] The northern Cascadia forearc takes up most of the strain transmitted northward via the Oregon Coast block from the northward-migrating Sierra Nevada block. The north-south contractional strain in the forearc manifests in upper-plate faults active during the Holocene, the northern-most components of which are faults within the Bellingham Basin. The Bellingham Basin is the northern of four b...

2009
Jason P. Briner P. Thompson Davis Gifford H. Miller

Melting glaciers and ice caps on Baffin Island contribute roughly half of the sea-level rise from all ice in Arctic Canada, although they comprise only one-fourth of the total ice in the region. The uncertain future response of arctic glaciers and ice caps to climate change motivates the use of paleodata to evaluate the sensitivity of glaciers to past warm intervals and to constrain mechanisms ...

Journal: :iranian journal of science and technology (sciences) 2007
k. moradi harsini

holocene in southwest khuzestan is represented by a fluvio-tidal succession termed thebahmanshir series which consists of two clayey layers separated by silty sand to silt beds. this paperdescribes the geotechnical properties of the clayey layers that have wide exposure in the lowlands of thepersian gulf coast. studied layers are generally clay sized and consist of a lesser percentage of clay m...

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