Fossil dating methods ppt
These items are called inclusions - foreign bodies of rock or mineral enclosed within another rock.
Because the sedimentary rock had to have formed around the object for it to be encased within the layers, geologists can establish relative dates between the inclusions and the surrounding rock.
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Let's say, in this set of rock strata, that we found a single intrusion of igneous rock punching through the sedimentary layers.
It sounds like common sense to you and me, but geologists have to define the Principle of Original Horizontality in order to make assumptions about the relative ages of sedimentary rocks. Say you have a layer of mud accumulating at the bottom of a lake. More sediment accumulates from the leaf litter and waste of the forest, until you have a second layer.
In this lesson, we'll learn a few basic principles of stratigraphic succession and see whether we can find relative dates for those strange strata we found in the Grand Canyon.