Dating methods wiki
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Geologists still use the following principles today as a means to provide information about geologic history and the timing of geologic events.
These strata make up much of the famous prominent rock formations in widely spaced protected areas such as Capitol Reef National Park and Canyonlands National Park.
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.
Faults are younger than the rocks they cut; accordingly, if a fault is found that penetrates some formations but not those on top of it, then the formations that were cut are older than the fault, and the ones that are not cut must be younger than the fault.
Finding the key bed in these situations may help determine whether the fault is a normal fault or a thrust fault.
The principle of faunal succession is based on the appearance of fossils in sedimentary rocks.
As organisms exist at the same time period throughout the world, their presence or (sometimes) absence may be used to provide a relative age of the formations in which they are found.
He also found that certain animals were in only certain layers and that they were in the same layers all across England.
Due to that discovery, Smith was able to recognize the order that the rocks were formed.
While digging the Somerset Coal Canal in southwest England, he found that fossils were always in the same order in the rock layers.
As he continued his job as a surveyor, he found the same patterns across England.
Explanations: A – folded rock strata cut by a thrust fault; B – large intrusion (cutting through A); C – erosional angular unconformity (cutting off A & B) on which rock strata were deposited; D – volcanic dyke (cutting through A, B & C); E – even younger rock strata (overlying C & D); F – normal fault (cutting through A, B, C & E).