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This activity was selected for the On the Cutting Edge Exemplary Teaching Collection Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories.Correlation is, as mentioned earlier, the technique of piecing together the informational content of separated outcrops.However, as previously noted, times of volcanism and metamorphism, which are both critical parts of global processes, cannot be correlated by fossil content.Furthermore, useful fossils are either rare or totally absent in rocks from Precambrian time, which constitutes more than 87 percent of Earth history.Such an array of attributes represents an ideal, and much stratigraphic geology is rendered difficult because of departure of the natural fossil assemblage from this ideal.Nevertheless, there is no greater testimony to the validity of fossil-based stratigraphic geology than the absolute dates made possible through radioactive measurements.
Failing that, the repetition of a certain layered sequence (e.g., a black shale sandwiched between a red sandstone and a white limestone) lends confidence to physical correlation.
To this day, fossils are useful as correlation tools to geologists specializing in stratigraphy.
In dating the past, the primary value of fossils lies within the principle of faunal succession: each interval of geologic history had a unique fauna that associates a given fossiliferous rock with that particular interval.
As was mentioned at the outset of this article, fossil assemblages.
Using fossils simply for identification purposes, Smith constructed a map of the various surface rocks outcropping throughout England, Wales, and southern Scotland.
This requires that the lifespan of the fossil species be but a moment of time relative to the immensity of geologic history.