Radioactive dating lesson
Fossils are generally found in sedimentary rock not igneous rock.
Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years.
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Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.
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To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.Or, just print the graph for all pupils to use independently....Unlike people, you can’t really guess the age of a rock from looking at it. Scientists look at multiple sources for evidence that a species has evolved overtime. You can use M & M"s to simulate how radioactive decay actually works.
They use a technique called radiometric dating to determine the absolute age of a fossil.
So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.