Bedrock 09 : The solid rock underlying gravel, sand, slay, etc.; any solid rock exposed at the surface of the earth or overlain by unconsolidated material. (AGI)
U.S. Department of the Interior, U.S. Geological Survey USGS, Landslide Hazards Program, Glossary, Washington, D.C. USA 2014. http://landslides.usgs.gov/learn/glossary.php, (ND/ Lndsld - Amer) {919}