The lithosphere. Rocks and minerals

The lithosphere is the Earth’s solid shell; it includes the crust and the upper part of the mantle. On land the crust has three layers: at the top, sedimentary rocks (clay, sand, sandstone, limestone, chalk) lie in layers; below them is granite and lower still a layer of basalt. Granite and basalt formed when magma cooled, so they are called igneous (magmatic) rocks; under the ocean the crust has two layers – sedimentary and basalt. Hard coal and oil formed from the remains of ancient plants and animals. The lithosphere is not whole but split into large plates that move a few centimetres a year. Where plates collide or separate, mountains (the Andes), island arcs (Japanese islands) and deep trenches (Mariana) form, and volcanoes and earthquakes are frequent: the Pacific “Ring of Fire” and the Alpine–Himalayan belt are examples. Minerals are divided into three groups: fuel (peat, coal, oil, gas), ore (iron, copper, aluminium, lead, zinc, gold, silver) and non-ore (rock salt, potassium salt, building materials).