Crust (geology) the crust. The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity. The crust of the Earth is of two distinctive types: Because both continental and oceanic crust are less dense than the mantle below, both types of crust "float" on the mantle. This is isostasy, and it's also one of the reasons continental crust is higher than oceanic: continental is less dense and so "floats" higher. As a result, water pools in above the oceanic crust, forming the oceans. The temperature of the crust increases with
Thickness (geology) the base of the groundwater layer to its surface – or in soil science for the vertical extent of soil horizons. Thickness (geology) Thickness in geology and mining refers to the distance across a packet of rock, whether it be a facies, stratum, bed, seam, lode etc. Thickness is measured at right angles to the surface of the seam or bed and thus independently of its spatial orientation. The concept of thickness came originally from mining language, where it was used mainly to indicate the workability of seams. It has since become an established term in earth science, for example