From AMS Glossary
"Rock debris formed by intensive frost action, derived from underlying or adjacent bedrock. Contrast with glacial drift." [Glossary of Arctic and Subarctic Terms (1955).]
Arctic, Desert, Tropic Information Center (ADTIC) Research Studies Institute 1955. Glossary of Arctic and Subarctic Terms. ADTIC Pub. A-105, Maxwell AFB, AL, . 90 pp.