The upper rock material that is more resistant to erosion than the underlying rock material; it also refers to a sedimentary unit of lower hydraulic conductivity than that of the underlying oil or gas reservoir rock that restricts upward migration of hydrocarbons, thus effectively capping the reservoir.
- Collins EW (1984) Styles of deformation in Permian strata, Texas Panhandle. Bureau of Economic Geology, The University of Texas at Austin Geological Circular 84-4. http://www.lib.utexas.edu/books/landscapes/publications/txu-oclc-11850252/txu-oclc-11850252.pdf. Accessed Oct 2016
- Machette MN (1985) Calcic soils of the southwestern United States.In: Weide DL (ed) Soils and quaternary geomorphology of the southwestern United States. Geological Society of America Special Paper, vol 203, pp 1–21. https://www.nrc.gov/docs/ML0037/ML003747879.pdf. Accessed Dec 2016