Wednesday, January 26, 2011

Determining Age of Earth’s Shell part.1

Determining Age of Earth’s Shell part.1

Definition of Age of Earth’s Shell

Age of Earth’s shell is the age of Earth’s sell layers that is calculated from the Earth formed until now. Commonly, we cannot determine exactly how old the rock layer (absolute age). Therefore, the calculation of age of Earth’s shell is fixed relatively (relative age).

Relative Age

The deepest rock layer is usually the oldest rock, because it is formed first than the rock above it, it is according to the formation principle of Earth’s shell. But because of the presence of tectonic power (endogenic power), for example a strong erosion, the rock initially lies in below changed to be above (surface). Accordingly, it is very hard to determine which the old rock layer and which the young one.

We can determine the age of Earth’s shell by means of fossils, because in various geological age, the condition of plants and animals is very different. In every period of Earth’s history it is always found unique creatures that only live in that era. The remain that has become rock from that creature can be used to determine the relative age of earth’s shell. Sometime fossils does not come from organism, for example fossil of ES In Green Island. The use of fossils to determine a relative age is based on the opinion that the kinds of animals and plants always undergo the change of shape during the history of Earth (undergoing evolution), the simpler its shape (unicellular animals), the older its age. Relative age is the age of Earth’s shell that is stated according to the kinds of creatures that live in that era. The era before the presence of organism is called Azoic or Archean Age. In the era, in a sediment rock it is not found fossil (very rare). The knowledge that study fossil is called paleontology.

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