Rocks and fossils: topic summary

A collection of small pieces of rock can be examined using a hand lens or a magnifying glass. Compare rocks on the basis of their appearance and their physical properties like hardness, texture and durability. Are they made up of grains or crystals? What changes occur when they are placed in water? Identify the use of rocks in the built environment like limestone blocks and ‘man-made’ rocks like bricks and tiles.

Naturally, rocks occur in three main forms: Sedimentary rocks, like limestone and sandstone, have been laid down in layers under the sea and become compacted over time. Igneous rocks (granite and basalt) are formed by heat – usually magma or lava from volcanoes. Metamorphic rocks (marble and slate) have changed from other rocks over time because of heat and/or pressure.