Absolute dating of rock layers
Dating > Absolute dating of rock layers
The first method of finding the absolute age of an object is by examining tree rings. If we looked at a cross-section ofa tree or log we would notice that all through it are concentric circles radiating out from the center to the bark. Each ring is also different, and the thickness of each ring is representative of the length of the growing season. In a year with a long growing season the tree ring for datiny year will be thick. If there wasa very long winter then there will be a thinner tree ring. Another method of determining absolute age is by looking at varves. They are most commonly found in glacial lake beds. Each spring or datijg when the glacier was melting the glacier deposits a ton of sediment it was carrying into strems of water that are melting off of it. When the meltwater reaches a lake the heaiest sediments sand and silt sink to the bottom quickly and eventually formed thick layers of light colored rock. Later in the year, by wintertime, the clay has had enough time to settle to the bottom and it forms a thin layer of dark colored rock. Because of the alternation between dark and light sediments we can use each dark band as a marker for one year.
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