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.

References in periodicals archive ?
Lake Timiskaming (100 km long, 200 m maximum depth) is the postglacial successor to glacial Lake Barlow; Barlow varved clays are present below the floor of Lake Timiskaming as far south as the McConnell Moraine (Fig.
The other type of sand is formed as a result of submarine erosion of Late Pleistocene varved clays up to 30 cm thick (alternating varved horizontal layers of brown clays and grey silty layers) are located in the nearshore, whereas below the sand accretion terrace on the bottom surface there are traces of submarine erosion, indicating sediment transport in NW direction.
The till is overlain by glaciolacustrine sands, silts or varved clays, up to 25 m in thickness.
Glaciolacustrine varved clays in the northern part of the lake depression were deposited approximately between 13 500 and 13 100 cal years BP.
The varved clays discovered during geological drilling under glaciofluvial deposits in the valleys of the Vaike Emajogi and Pedeli rivers and in the town of Valga may partly originate from earlier glaciations.
Following the ice retreat from the central and southern parts of the study area in the Saadjarve Drumlin Field, the deposition of glacial varved clays took place over a relatively short time period (up to 63 years).
In the northern and central parts of the lake the thickness of glaciolacustrine varved clays covering the till reaches up to 37 m (Fig.