ABSTRACT
During the late Pleistocene and Holocene, Sudanian and saharan vegetation formations were in direct contact in the central and southern Sahara. From the Middle Holocene on the savanna system of the Sahel evolved due to intensive human impact-mainly fire and pasture. Investigations on Late Pleistocene and Holocene records from the northern Niger evidenced the direct contact of sudanian to saharan vegetation formations between 19°N and 20°N. This configuration was present during the early and Middle Holocene, and also during the Late Pleistocene the dryer periods contemporary to the High Glacial/Ka-nemien were not severe enough to eliminate the remnants of the sudanian alluvial vegetation in northern Niger. Records from the depression of Segedim showed the presence of regular ash -and charcoal layers in the fine laminated sediments from the Middle Holocene on. This is only to explain by intentionally set fires which may have served as hunting fires or to provide free access to the lake for small livestock keepers.
