Drift (geology)

In geology, drift is a name for all sediment (clay, silt, sand, gravel, boulders) transported by a glacier and deposited directly by or from the ice, or by glacial meltwater.

[1] In the United Kingdom, drift is also applied as a general term for all surficial, unconsolidated, rock debris and sediment that is moved from one place to accumulate in another and mapped separately or otherwise differentiated from underlying bedrock.

[1][2] In 1839, geologist Roderick Murchison[3] introduced the term drift to describe unconsolidated surficial sediments previously called diluvium.

The drift hypothesis further proposed that these sediments had been released as the ice melted, to fall and accumulate on the sea floor in comparatively recent times, e.g. during the Quaternary Period.

This term continued to be used long after the drift hypothesis had been abandoned in favor of the glacial theory.

Rounded erratic boulders of crystalline rock composition next to Ordovician limestone bank along the shoreline in NW Osmussaar , Estonia .