Granite Layer

(granite-gneiss or metamorphic granite layer), the conventional name for a layer of the earth in which longitudinal seismic waves travel at a velocity of 5.0–6.5 km/sec. On continents, the layer is covered by a sedimentary mantle, with the exception of the shields where the layer is exposed; the layer is typically absent on the ocean floor. In addition to granites, the layer includes gneisses and other metamorphic and igneous rocks.