GEOL-1010 Lecture Notes - Lecture 8: Half-Life, Fossil Fuel, Radiocarbon Dating
4 Oct 2016
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Geol 1010 lecture 8 part 2: absolute ages. Geology in the news: a fossil bug inside a fossil lizard inside a fossil snake. Useful in some situations: 2) radiometric. Non-radiometric techniques: varves: really thin layers that alternate between lighter and darker bands. They often form in lakes and ponds where they freeze over in the winter. The layers are formed by the temperature change between summer and winter. Lighter bands: formed in summer when the water flows normally. Each pair of light and dark bands = 1 year. Count the pairs and this can give information about the lake and how many years it continued this cycle. They only form under the right conditions. Information won"t work farther from that specific area. Can"t allow the sediments to get mixed together due to disturbances by shells, crabs, etc. because then the layers will be lost: works better in lakes with little to no bottom life, dendochonology.
