The depth of the Moho (Mohorovicic) discontinuity, which marks the boundary between the crust and mantle, varies systematically with crustal type and thickness: continental crust beneath mountain ranges like the Himalaya is thickest (due to crustal shortening and thickening from continental collision), continental crust beneath plains like the Ganga plain is of intermediate, more typical continental thickness, and oceanic crust beneath the Bay of Bengal is the thinnest, giving the shallowest Moho depth there.