Describe the origin of the main types of rock on Earth's crust.

There are 3 main types of rock at Earth's crust - Sedimentary, Igneous, Metamorphic. Different types of rock: (I) Igneous - Mode of origin: From molten volcanic activity, solidifies internally (Granite) or externally (Basalt). Nature - Grained rock, ice by crystalline, generally ubiquitous nature. Basalt - Granite, Basalt, Andesite etc. of percent plateau of India. (II) Sedimentary - Mode of origin: Deposition of sediment, forced water, gravel etc. Nature - Amber plumes, layered, can contain organic matter also. Chalk, Limestone etc. Alluvied plains. (III) Metamorphic - Mode of origin: Intense heat/pressure on both all kinds of rock. Nature - Crystalline, banding occur on basis of Permus. Metamorphic - igneous, slate/foliated, gneiss. Sedimentary - Deposition.