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

A rock is an aggregate of 2 or more minerals. Rocks are majorly of 3 types - Igneous, Sedimentary and Metamorphic

Types of Rock

Rock | Nature | Origin

(i) Granite,

Volcanic breeda | (a) Rich in mineral crystals

(ii) No fossils found

(iii) No layers

(iv) Either plutonic or extrusive | (a) Formed due to cooling & solidifying of magma

(i) Limestone

(ii) Sandstone

Coal | (i) No capital of minerals

(ii) High fossil preservation

(iii) Stratched | (i) Weathered material of rocks are transported by various agents & batiety, to form rock

Both types are crucial for economy. Rock formation is understood from the study of geology & hence studying rock formation is understood

Diagram showing Rock Cycle:

Metamorphic -> melting -> Magma -> Cooling -> Igneous -> weathering -> Sediment -> cementation -> Sedimentary -> heating & pressure

Rocks form the very basis of geography & hence studying rock formation is understood