摘要:

The extent of ice on the south side of the Mont Blanc massif during two late‐glacial readvances is known primarily from the distribution of crystalline erratics on sedimentary and metasedimentary terrain, and from the distribution of end moraines and outwash remants. Similar dual moraine complexes are found elsewhere in upper Val d'Aosta and indicate that the pattern is regional in character. During the earlier readvance equilibrium‐line altitudes were ca. 450 ± 50m lower than at present, whereas during the later readvance they were ca. 350 ± 50 m lower. The moraines, not yet closely dated, were deposited sometime after 14,20014C Years ago by which time Lago'd Alice near the margin of the würm moraine system at Ivrea had been deglaciated, and before 8400 years ago, at which time Rutor Glacier in upper Val d'Aosta was no larger than at present. The younger moraines are believed to correlate with Egesen moraines on the north side of the Alps, whereas the older set may either correlate with an early phase of the Egesen or with Daun a

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1982.tb00530.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Altogether 62 radiocarbon dates from 17 pollen diagrams (16 sites) of Late Weichselian lake sediments in S Sweden have been determined to establish the chronostratigraphic sequence as defined by the pollen stratigraphy. This method of controlling the dates and the validity of the assumed synchronous Nordic climatostratigraphy are discussed. Most of the dates sufer from age erors, mainly caused by contamination by redeposited organic material. The effect of this source of error increases with decreasing percent of organic carbon in the deated samples. The significance of these problems for the Late Weichselian chronostratigraphic subdivision as well as ways of solving them are discussed.

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1982.tb00531.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Holocene and Late Quaternary talus, lobate rock glaciers, and moraines within Audubon Cirque, Colorado Front Range, were assigned reltive ages using the following age‐dependent criteria: fresh‐weathered ratio, pitting, weathering rind development, angularity, and surface, oxidation of boulders, together with lichen cover and largest lichen diameter. Principal Component scores, yielding four major groups of deposits (relative age units C, R, E and V, from youngest to oldest). Tentative correlation with other Colorado Late Quaternary sequences suggests that unit C is of Gannett Peak age (100–300 years B. P.), unit R of Audubon age (950–1850 years B. P.) unit E of Early Neoglacial age (3000–5000 years B. P.), and unit V of Late Pinedale age (about 10,000 Years B. P.). Correlation is problematic due to differences in operationsl definitions of relative dating parametrs between workers, and because climatic and lithologic variations between areas may confound

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1982.tb00532.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1982.tb00533.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The ahermatypic coralLophelia pertusawhich produces aragonitic skeletons is widely distributed along the Norwegian coast. Specimens from a number of localities have been analyzed for oxygen and stable carbon isotope composition and14C age. Stable isotope ratios of recent corals provide information on growth rate and seasonality of oceanographic conditions.Lopheliacan be useful in paleoenvironmental reconstructions.14C dates of fossilLopheliafrom Drøak in the Oslofjord, collected from 20 m ahove and 40 m below present day sea‐level, indicate regional extinction between 8700 and 7800 years ago. We suggest that the extinction resulted from the cut‐off of deep waters by a rising sill in connection with the postglacial shoreline displacement. Radiocarbon dating of coral bushes suggests a fairly rapid growth rate as older and younger parts of recent corals do not reveal any difference in activity despite the short time scale of the history of bomb‐produced14C in the

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1982.tb00534.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Book reviewed in this article:Voipio, Aarno (ed.): The Baltic Sea

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1982.tb00535.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1982.tb00536.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY