In geology, country rock is the rock native to an area, in contrast to any intrusion of viscous geologic material, commonly magma, or perhaps rock salt (in salt domes) or unconsolidated sediments.[1]
Magma is typically less dense than the rock it intrudes, widening and filling existing cracks, sometimes melting the already-existing country rock.[2]
The term "country rock" is similar to, and in many cases interchangeable with, the terms basement and wall rocks.
Country rock can denote the widespread lithology of a region in relation to the rock which is being discussed or observed.