Abstract
There are dune generations of different age in the southern Sahara (Erg of Bilma) as well as in the Sahel of the eastern part of the Republic of Niger. They differ by their form and grade of weathering. Dune forming and pedogenesis reveal significant changes of geomorphogenetic and climatologic processes in this area at the end of the Pleistocene and Holocene. Fixed ancient dunes reveal, that because of dislocation of wind patterns arid climate then reached further south than the present southern margin of the Sahel. After 16 000 BP precipitation-rates gradually increased. This tendency had its climax during the great humid period of the early Holocene (Tchadien), which since 10 000 BP produced freshwater lakes in the Erg of Bilma (south Sahara/north Sahel). The younger Pleistocene dunes weathered deeply during this humid time. A short arid period about 6500 BP produced a second generation of dunes in the southern Erg of Bilma (south Sahara/north Sahel). The younger Pleistocene dunes weathered deeply during this humid time. In the Erg of Bilma then the youngest, the third generation of totally unweathered, migrating dunes was formed chiefly from the slightly consolidated sands of the Holocenic, second dune generation. -from Authors
Original language | English |
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Pages (from-to) | 1-17 |
Number of pages | 17 |
Journal | Zeitschrift fur Geomorphologie |
Volume | 34 |
Issue number | 1 |
State | Published - 1990 |
Externally published | Yes |