(a) Describe four characteristics… | Geography

Question 1 Report

(a) Describe four characteristics of igneous rocks

(b) Using specific examples, state four ways in which metamorphic rocks are useful to man.

Answer

Answer Details

(a) Four characteristics of igneous rocks

Crystalline: they are made of interlocking mineral crystals formed when molten magma or lava cooled and solidified.
Non-stratified (no layers): they occur in solid masses without bedding planes or strata.
Contain no fossils, because they were formed from molten material and never laid down as sediments.
Generally hard, crystalline and non-porous, so they resist weathering; the crystals are large when the rock cooled slowly at depth (e.g. granite) and small/fine when it cooled quickly at the surface (e.g. basalt).

(b) Four ways metamorphic rocks are useful to man (with examples)

Marble (from limestone) is used for building, floor and wall tiles, statues, monuments and decoration.
Slate (from shale/clay) splits into thin sheets and is used for roofing, floor slabs and formerly writing boards.
Quartzite (from sandstone) is very hard and is used as building stone, road-making aggregate and for making glass and abrasives.
Graphite (from carbon-rich rock) is used for pencil leads, lubricants and electrodes; and gneiss is used as a durable building and paving stone (marble/graphite may also carry valuable minerals).

(a) Describe four characteristics of igneous rocks (b) Using specific examples, state four ways in which metamorphic rocks are useful to man.