摘要:

True ‘periglacial’ forms and deposits of late (and middle) Pleistocene age can be recognized in the Drakensberg and the adjacent parts of the Cape Province in the latitudinal zone 28° 30′‐31°20′ S; lower limits in the eastern Cape and Natal appear to lie near 1500–1800 m, rising from southwest to northeast, and at 2600 m in Lesotho. Significant nivation in the Drakensberg is also indicated, but at higher elevations. Alleged ‘periglacial’ phenomena in Rhodesia, the Transvaal, the Cape Folded Ranges and their coastal margin are not acceptable as such and include no evidence for cryonival or geliflual proceses. Nonetheless, there is bonafide evidence for several phases of accelerated Pleistocene frost‐weathering, including sections of the Cape Coast that experience next to no frost today and would require a winter temperature depression of at least 10° C. It cannot be disputed that southern Africa has experienced cold, glacial‐age climates, but there is a serious problem about many of the geomorphological observations o

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1973.tb00245.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

It is often difficult to establish in the field the origin of the B horizon of buried truncated palaeosols. However, infrared spectral configurations of electrodialyzed humic acids can be used as a diagnostic tool. Decreased absorption on passing from 2500 to 1800 cm‐1indicates the presence of a chernozemic B horizon. The difference was explained on the basis of the conditions that existed at the time of the formation of these horizons. Burial did not change the structure of the humic substances responsible for the infrared spectral configuration

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1973.tb00246.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Broughton Island is 50 km from the eastern margin of the 6,000 km2Penny Ice Cap. During the early Wisconsin (>54,000 BP) A younger glacial readvance is delimited by lateral moraines and glacio‐marine deposits14C dated at 24,100±850 BP; sea level was±18 m. During th last Wisconsin the glaciers terminated some distance inland from Broughton Island and sea alevel at 9,850±250BP was +5 m on Broughton Island. The head of Maktak Fiord, which presently contains a majour outlet glacier from the Penny Ice Cap, was deglaciated about 6,00

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1973.tb00247.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Detailed climatic records from land (glaciation curves, fossil records, etc.), sea (eustatic changes, deep‐ses date), and air (Greenland 018curve) are almost identical for the last 35,000 years. This cannot be a mere coincidence: it indicates that even minor fluctuations are caused by global climatic changes. The various records seem to be easily correlated with each other. The Last Ice Age is characterized by drastic changes between colder and warmer periods. The Present (Flandrian) Interglacial (Holocene Epoch) is also characterized by climatic fluctuations, although of minor amplitude. Analysis of peaks and bottoms in six Atlantic deep‐sea cores gives a climatic sequence identical to the eustatic transgression/regression sequence, indicating the recording of global short‐term warm/cold fluctuations. From these fluctuations, the climatic cyclicity was calculated. Two drastically frequency‐changing cycles were found, one varying from 230 to 1,000 years and one from 1,000 to 3,600 years. A third cycle of 21,000 years was also estabished. The transition from the Last Ice Age to the Present Interglacial is marked by three major steps towards interglacial conditions; viz. at 12,7000, 10,000 and 9,300 radiocarbon years B. P. The 10,000 boundary has earler been suggested as the Pleistocene/Holocene b

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1973.tb00248.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY