Alternative dating in
Studies done on the European continent soon demonstrated the universal validity of index fossils.
That is, an index fossil corresponded to a very specific point in the geologic column.
If rock type mattered then we would expect a zircon crystal's lead content to vary dramatically within the Cambrian or Cretaceous strata according to their local rock types. Cosmic rays, on the other hand, don't penetrate that far into the earth to begin with, so we can rule them out.
Then the paleontologists use the geologists' dates as evidence for the age of the fossils! The relative order of the strata was first determined by the principles of stratification. Beagle, a very strong Bible believer, made it a point to have a copy of Lyell's book for the ship's library.
(The principle of superposition was recognized as early as 1669 by Steno.) Reverend Benjamin Richardson and Reverend Joseph Townsend were a couple of early geologists involved in this work. Obviously, even Lyell was not pushing evolution at the time.
Any kind of object clearly restricted to a specific point in the geologic column would do just fine.
If green dice were found only in the middle Ordovician strata, they would make excellent "index fossils." Evolution should be seen as an explanation of the faunal succession, a succession which was worked out long before evolution dominated the scene.