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Geological evolution

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  • 1. Geological Evolution Grade 8 Science
  • 2. Geological Evolution refers to Earth’s gradual change over its history. QuickTime™ and a decompressor are needed to see this picture.
  • 3. One of the ways in which the Earth evolves is through plate tectonics, which is the process that explains how large pieces of the Earth’s outermost layer move and change. QuickTime™ and a decompressor are needed to see this picture.
  • 4. One aspect of plate tectonics is the Continental Drift Theory, which states that the gradual shifting of Earth’s plates causes continents to change their global positions over time. QuickTime™ and a decompressor are needed to see this picture.
  • 5. The boundary formed by the collision (coming together) of two plates is called a convergent plate boundary. QuickTime™ and a decompressor are needed to see this picture.
  • 6. The boundary formed between two plates moving apart from each other is called a divergent boundary. QuickTime™ and a decompressor are needed to see this picture.
  • 7. Scientists believe that at one point in Earth’s history all of the continents were once connected to form a gigantic land mass called Pangaea, also known as the super-continent. QuickTime™ and a decompressor are needed to see this picture.
  • 8. Relative Dating The use of information about rock layers and the fossil record to determine the age relationships between rocks is called relative dating.
  • 9. The Law of Superposition is the principal that states that each layer of sedimentary rock is older than the layer above it. QuickTime™ and a decompressor are needed to see this picture.
  • 10. Law of Superposition In simple terms, this means that the top layer of sedimentary rock is the youngest and the bottom layer is the oldest. QuickTime™ and a decompressor are needed to see this picture.
  • 11. An extrusion is an igneous rock layer that forms when lava cools and hardens on Earth’s surface. QuickTime™ and a decompressor are needed to see this picture.
  • 12. Extrusions are usually horizontal and can be treated as a sedimentary rock layer when trying to use relative dating. QuickTime™ and a decompressor are needed to see this picture.
  • 13. An intrusion is when magma cools and hardens beneath Earth’s surface. These layers are not horizontal and show where magma has broken through sedimentary rock layers. QuickTime™ and a decompressor are needed to see this picture.
  • 14. Intrusions are always younger than the sedimentary rock layers they have broken through. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture.
  • 15. A fault is a break or a crack in Earth’s crust. A fault is always younger than the rock layers that it breaks through. QuickTime™ and a decompressor are needed to see this picture.
  • 16. An unconformity is where a newer rock layer meets a much older rock layer. It is a gap in the geological record. It shows were some rock layers have been lost due to erosion. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture.
  • 17. An index fossil is a fossil of an organism that was present on Earth during a short time range, but was common on the Earth. QuickTime™ and a decompressor are needed to see this picture.
  • 18. Index fossils are used to date rock layers, because scientists know that the rock layer in which an index fossil is found is the same age as the index fossil. QuickTime™ and a decompressor are needed to see this picture.