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Evidence for Evolution

Problems

Paleontology

Biogeography

Problem : How can we tell the age of a fossil?

The age of a fossil relative to other fossils can be determined by where in relation to each other the fossils are found in rock strata. The absolute age of a fossil can be found through radioactive dating.

Problem : How are fossils formed?

Fossils are formed when a piece of bone or other material is buried by sediment. Over long periods of time, chemicals from the surrounding rock leach into the object until only a rock shaped like the original object is left.

Problem : Aside from fossils, what other information can be contained in rock strata?

The chemical make-up of rocks can tell us what environmental conditions may have been like. They can tell us what kinds of gases may have been in the atmosphere, how much moisture was in an area, or if any cataclysmic events occurred, such as volcanic eruptions or meteor strikes.

Problem : Why are there so many gaps in the fossil record?

Fossilization is a rare event. An object must remain in the right kind of conditions undisturbed for a very long time for a fossil to form. Once formed many fossils are lost to the crushing action of geological movements or to erosion of rock faces.

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