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Third, magnetism in rocks can be used to estimate the age of a fossil site.This method uses the orientation of the Earth's magnetic field, which has changed through time, to determine ages for fossils and rocks.Sometimes sedimentary rocks are disturbed by events, such as fault movements, that cut across layers after the rocks were deposited.
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For example, based on the primate fossil record, scientists know that living primates evolved from fossil primates and that this evolutionary history took tens of millions of years.
By comparing fossils of different primate species, scientists can examine how features changed and how primates evolved through time.
Second, it is possible to determine the numerical age for fossils or earth materials.
Numerical ages estimate the date of a geological event and can sometimes reveal quite precisely when a fossil species existed in time.
These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.
As these changes have occurred, organisms have evolved, and remnants of some have been preserved as fossils.The layers of rock at the base of the canyon were deposited first, and are thus older than the layers of rock exposed at the top (principle of superposition).In the Grand Canyon, the layers of strata are nearly horizontal.Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.Mountains have been built and eroded, continents and oceans have moved great distances, and the Earth has fluctuated from being extremely cold and almost completely covered with ice to being very warm and ice-free.The age of the fossil must be determined so it can be compared to other fossil species from the same time period.Tags: Adult Dating, affair dating, sex dating