Describe the nature and mode of origin of the main types of rock at the earth's crust.

The Earth's crust is [8-40 km] and contains rocks of all three kinds - igneous, sedimentary, & metamorphic. Types of Rocks (3) Igneous => Naturistic [oreographic] for Granite composition dependent on minerals in crust is consolidated [oceanic or continental] => High density ( > 3 gm/cc) for oceanic crust with [low density for continental]. => [Mode of origin] => Convection current in the mantle causes magma to uplift and form crustal [igneous rock via j fractioned crystallization].

B Sedimentary Rocks: Top layers of the crust, formed after million of years of deposition. Nature: The Penerine layers => layers close to those contain [immersitely] The deeper layers have shales & shudidily origin: sedimentation, Carbonate precipitation C Metamorphic Rocks: Contains rocks like basins, [Quartzite] etc. Nature: Heavily [metamorphiced], All fossil evidences give chemical altered. Mod of origin: Subduction Zone, high Temp E connection and high pressure leads to chemical alteration. These three rocks define the entire of crust, simultaneously conveying into each other.