摘要:

Twenty‐five fossil insect assemblages are described from discrete lenses of or‐ganic material in a gravel sequence at Four Ashes. The youngest date of 30,500 years B.P. obtained on the organic materialhas confirmed that the till overlying the gravels is Late Devensian (Weichselian) in age. The analyses of the insect faunas have shown conclusively for the first time the existence of climatic changes in one geographic area during the Early and Middle Devensian in Britain. Some of the earliest insect faunas can be correlated with the Brorup Interstadial, when boreal forests existed in the English Midlands. It is suggested that a cold period prior to 43,000 years ago (but post‐Brorup) may have caused the elimination of the trees, because around 40,000 years ago the insects indicate that there was a rapid climatic amelioration when it was warm enough for trees to grow again in that area. Around 36,000 years ago there was another climatic deterioration when the thermophilous insect species were replaced by a large number of arctic stenotherms and a tundra type of environment. This cold period lasted for at least 6,000 years and probably became increasingly severe with the approach of the main Devensian ice advance sometime after 30,500 year

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1973.tb00254.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Profiles with till and stratified meltwater sediments have been examined. Structural and morphological conditions indicate a deposition of till in the same environment as the stratified sediments. The till is interpreted as flow till which originated from considerable amounts of supraglacial material.

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1973.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1973.tb00253.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY