Methods of dating rock layers

The table below summarises key features: Gastrioceras listeri is a particularly good example of a ZONE fossil.As it is free swimming it could have travelled a considerable distance.The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.This restriction extends to animals that consume seafood in their diet.

What can be deduced from our two distinct faunas in terms of their usefulness in the relative dating of rocks?Familiar to us as the black substance in charred wood, as diamonds, and the graphite in “lead” pencils, carbon comes in several forms, or isotopes.One rare form has atoms that are 14 times as heavy as hydrogen atoms: carbon-14, or C ratio gets smaller.(relative geologic timescale) (b) Absolute Dating Following the discovery of radioactivity in 1895, radiometric dating techniques were developed to determine the absolute ages, i.e. In the succession of strata, each layer represents the geographical conditions that occurred over that area at the time the layer was deposited.In each period of earth's history different fauna and flora evolved with similar faunas being characteristic of similar beds.

Methods of dating rock layers