Varved Clays

Varved Clays 

the sediments of lakes that are located near the terminus of an inland glacier. Varved clays are characterized by fine regular bedding consisting of summer and winter layers which are composed of coarser (sandy-silty) or finer (clayey) material, respectively. The thickness of a pair of layers is usually less than 1 mm but may sometimes reach several cm. In lake sections adjacent to the glacier, the thickness of the layers is usually greater than in sections that lie at a distance from the glacier. Within the large layers there is microbedding, which is associated with changes in the weather and the intensity of glacier thawing. Varved clays are found in Byelorussia, the Baltic republics, and in the northern European USSR. Abroad they are found in Scandinavia, in northern Poland, and the German Democratic Republic. A calculation of the number of annual layers is used for the geochronology of glacial and postglacial ages.