Copyright © 2007 Dorling Kindersley
The Earth has many natural resources that make life in the modern world possible. For example, rocks are used in their natural state to make buildings, but they can also be processed to provide the materials we need to make anything from bridges and cars to silicon chips and jewellery. FOSSIL FUELS provide us with energy, but so does water flowing down rivers, the wind, and even the Sun. Resources such as rocks and fossil fuels must often be extracted from the ground by MINING.
Rocks contain a great variety of useful minerals. Mining and quarrying involve blasting, drilling, and digging up rocks to extract the minerals. Most mines and quarries are worked for building materials, coal, metal ores, and gem-rich rocks and deposits. Mining is noisy, dusty, and can require the use of dangerous chemicals, all of which can cause environmental damage.
A gold mine in Indonesia is an example of an underground mine, where rock is dug out by machinery deep under the surface. There are two main types of underground mine: shaft mines, which are normally deep, with vertical shafts leading to tunnels; and drift mines, which are near the surface. Underground mining is very dangerous because of possible flooding, explosive gases, and falling rocks.
At the Bingham copper mine in Utah, USA, the ore deposit is close to the surface and is extracted by opencast mining. Opencast mining is cheaper and easier than underground mining because no shafts have to be dug, but it does more damage to the landscape. Once the ore is dug up, it is carried away by trucks, railway, or conveyor belts.
Coal, oil, and gas are called fossil fuels because they were formed from the remains of animals and plants that were buried by layers of sediment millions of years ago. Most of the energy used today comes from burning fossil fuels. Fossil fuels are non-renewable sources of energy, which means that once they have been used they can never be replaced.
Many of the world’s oil and gas supplies are found in rock under the sea, from where they are extracted through pipes drilled into the seabed from production platforms. Where oil and gas are found together, they were formed from the bodies of microscopic marine organisms. Oil is a source of chemicals as well as fuel.
Coal is formed by the burial of plant remains before they rot completely. Surface deposits of vegetation form layers of peat that become lignite and coal as they are more deeply buried over time. Burial compresses the plant remains and squeezes out any water. Further pressure turns coal into anthracite.