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The depth at which either is found can vary dramatically.In the Grand Canyon area the Cambrian lies beneath a huge column of strata; in California's Mojave Desert portions of the Cambrian are exposed at the surface.By the 1830's Adam Sedgwick and Roderick Murchison established a correlation between the various types of fossils and the rock formations in the British Isles.It was found that certain fossils, now referred to as index fossils, were restricted to a narrow zone of strata.Noah's flood might just as easily deposit the same crystal in one place as another. Pressure has nothing to do with it, and zircon crystals all have about the same density as their total lead content is small.Just what is it that a Cambrian stratum has which a Cretaceous stratum lacks?By 1830 Lyell's famous textbook, Principles of Geology, came out. Such was the age of the great creationist geologists!The principle of faunal succession in the geologic record was established by direct observation as early as 1799 by William Smith.
One creationist editor, who is more mellow than his unfortunate statement suggests, phrased the argument thus: Unfortunately the geologists date the rocks as the paleontologists tell them to. That passage might have come out of one of Henry Morris' books, except that Morris usually avoids crude slander. Hovind is not aware of the fact that by 1815 the broad outlines of the geologic column from Paleozoic times onward had been worked out by people who were mostly geologists.
Once the worth of index fossils had been established on the basis of stratification studies, they could logically be used to extend the correlation of rock formations to other continents.
At this point in time they were simply a useful tool for correlating rock formations.
Your chances are 6.2 billion to one of getting the right order for all thirteen.
And, when you consider that each period can also be divided into "upper, middle, and lower," the odds of arranging them in the correct order by pure chance become astronomical. It has correctly placed the Cambrian between the Precambrian and the Ordovician, the Ordovician between the Cambrian and the Silurian, the Silurian between the Ordovician and the Devonian, and so forth.
By then, the relative ages (order) of the geologic column had already been worked out in some detail.