Parent rock, also referred to as
substratum, refers to the original rock from which something else was formed. It is mainly used in the context of
soil formation where the parent rock (or
parent material) normally has a large influence on the nature of the resulting soil. The term is also used in the context of
metamorphic rocks where again the parent rock or
protolith refers to the original rock before metamorphism takes place. Parent rocks can be
sedimentary,
igneous or
metamorphic.