The Earth
Curriculum:
- Observe and classify different types of rocks and soils.
- Research simple models of the internal structure of the Earth.
- Examine fossils and research the fossil record.
- Discuss the fossil record as a guide to estimating the age of the Earth.
- Learn about most recent estimates of the age of the Earth.
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The structure of the Earth
The Earth, which is estimated to be 4600 million years old, has three layers. The outer layer, on which we live, is called the crust and is made of solid rock. Compared to the other layers, this layer is very thin. The middle layer is called the mantle. It is made of soft rock, which is soft enough to flow very slowly. The inner layer is the core and is made of metal, mainly iron and nickel. |
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Rocks
The rocks in the Earth’s crust are made from different minerals but can be divided in three group; igneous, sedimentary and metamorphic rocks.
Igneous rock is formed when rock melts and cools again, forming crystals. Sedimentary rock is built up from particles compacted and cemented together. The third group of rocks, metamorphic rock, are formed by the action of high temperatures and pressures on the rock.
Fossils
Fossils are found in sedimentary rock. When an animal or even plant dies and is quickly covered by sediment, which will built up layer by layer, and will become part of the sedimentary rock. Because oxygen and bacteria have a difficulty reaching the dead remains of the organism, it is preserved well. Fossils can be either imprints or remains, e.g. bones, of these organisms.
Fossils help dating the rock. If a specific species of fish lived between 50 and 60 million years ago, the layer of rock it is found in dates from that period. They can also help you tell where the rock is from. If the fish lived in tropical waters for example, then the rock was formed in tropical waters, even if it was found in Klazinaveen. The fossils also help us trace the evolutionary steps of a species. There are a lot of extinct species, which we only know about because of the fossils we have found.
The rocks in the Earth’s crust are made from different minerals but can be divided in three group; igneous, sedimentary and metamorphic rocks.
Igneous rock is formed when rock melts and cools again, forming crystals. Sedimentary rock is built up from particles compacted and cemented together. The third group of rocks, metamorphic rock, are formed by the action of high temperatures and pressures on the rock.
Fossils
Fossils are found in sedimentary rock. When an animal or even plant dies and is quickly covered by sediment, which will built up layer by layer, and will become part of the sedimentary rock. Because oxygen and bacteria have a difficulty reaching the dead remains of the organism, it is preserved well. Fossils can be either imprints or remains, e.g. bones, of these organisms.
Fossils help dating the rock. If a specific species of fish lived between 50 and 60 million years ago, the layer of rock it is found in dates from that period. They can also help you tell where the rock is from. If the fish lived in tropical waters for example, then the rock was formed in tropical waters, even if it was found in Klazinaveen. The fossils also help us trace the evolutionary steps of a species. There are a lot of extinct species, which we only know about because of the fossils we have found.
