1 Any sediment laid down by, or in association with, the activity of glacial ice. The term is often widened to include related submarine and lacustrine deposits. The British Geological Survey has used it to refer to all superficial (i.e. drift) deposits. It was introduced by C. Lyell (1797–1875), who suggested that glacial deposits were laid down by melting icebergs which drifted across an ice-age sea covering Britain. This old term is now largely superseded by more recent classifications.
2(instrumental) The change in the output of a recording device due to internal factors. Systematic drift can be compensated for by repeat readings at a base station.