Absolute dating geology definition
Continents move, carried on huge slabs, or plates, of dense rock about 100 km (62 miles) thick over a low-friction, partially melted zone (the (i.e., long, narrow belts at which one plate descends beneath another).
When rocks are subjected to high temperatures and pressures in collide, certain datable minerals grow and even regrow to record the timing of such geologic events.
To achieve this precision, geochronologists have had to develop the ability to isolate certain high-quality they contain and the daughter atoms formed by radioactive decay over billions of years of geologic time.
In addition, they have had to develop special techniques with which to dissolve these highly refractory minerals without contaminating the small amount (about one-billionth of a gram) of contained lead and uranium on which the age must be calculated.
It should be emphasized that linking sites together is essential if the nature of an ancient society is to be understood, as the information at a single location may be relatively insignificant by itself.
Similarly, in geologic studies, vast quantities of information from widely spaced outcrops have to be integrated.
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These units, called in their molten form, constitute major crustal additions.