(a) Due to volcanic eruption when lava solidifies outside the earth's surface extrusive or volcanic rocks are formed.
(b) Lava cools quickly and forms the rocks known as basalt, gabbros.
(c) It is a dark colored rock.
(d) The mineral grains in it are very small.
(e) It is a hard and heavy rock.
(f) It is used for building roads.
(a) When the molten magma solidifies below the earth's surface it forms an intrusive rock.
(b) Magma cools very slowly and forms rocks known as granite, diorite.
(c) It is dark grey in colour.
(d) The mineral grains in it are larger.
(e) They are commonly used as building stone.