Dating rocks fossils geologic events
Geologists still use the following principles today as a means to provide information about geologic history and the timing of geologic events.The principle of Uniformitarianism states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time.however, this process is not enough to allow the layers to change their positions.This principle allows sedimentary layers to be viewed as a form of vertical time line, a partial or complete record of the time elapsed from deposition of the lowest layer to deposition of the highest bed.This is because it is not possible for a younger layer to slip beneath a layer previously deposited.The only disturbance that the layers experience is bioturbation, in which animals and/or plants move things in the layers.While digging the Somerset Coal Canal in southwest England, he found that fossils were always in the same order in the rock layers.
The law of superposition states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it.A fundamental principle of geology advanced by the 18th century Scottish physician and geologist James Hutton, is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." The principle of intrusive relationships concerns crosscutting intrusions.