Late quaternary equatorial glacier fluctuations
Sammanfattning: On several occasions during the Quaternary, climate permitted equatorial glaciers to advance significantly. In East Africa, where the highest mountains of the African continent are located, evidence of three pre-Weichselian glaciations on Kilimanjaro, and two on Mount Kenya and Ruwenzori were recognized. During the last and better documented glaciation, glaciers were also active on other mountains in East Africa, in the Ethiopian Highlands and in and around the Sahara Desert. Present day glaciers are found on Kilimanjaro, Mount Kenya and Ruwenzori.From the investigations presented in this dissertation it can be inferred that glaciers on Mount Kenya were reactivated during the Neoglacial, which began some time after 6000 years before present (BP).A dated moraine in Teleki Valley and a continuous proglacial sediment chronology from Hausburg Valley show that the glaciers were active around 5000 BP, between 3200 and 2500 BP, between 1500 and 1000 BP and from 500 to 30 BP, i.e. the Little Ice Age.Glaciers once covered much larger areas of the South American Andesthan they do today. In the Ecuadorian Andes evidence of two major glaciations have been found, of which the second was synchronous with the latest glaciation in Africa and temperate latitudes. Evidence of Holocene glacial fluctuations from the Ecuadorian Andes is scarce. However, from historical documents it can be inferred that glaciers advanced during the Little Ice Age. A few radiocarbon dates suggest that Neoglaciation occurred.Using proglacial lake sediments a record of late Holocene glacial activity has been reconstructed for El Altar, Ecuador. At least twice during the last c. 1100 years, between c. 1100 and 800 BP and some time after 800 BP (Little Ice Age?), the climate favoured glacial growth. For equatorial glaciers changes in precipitation and cloudiness have had a stronger effect upon the mass balances than previously acknowledged. The synchrony of the Neoglacial events described in this dissertation and in other publications suggest that the climatic changes affecting equatorial glaciers had a global character.
KLICKA HÄR FÖR ATT SE AVHANDLINGEN I FULLTEXT. (PDF-format)