Or it could be a fragment of ancient soil or sediment found in a younger stratum.

The 1997 specimens indicate an individual about 45% longer than the holotype; they were also found in a younger stratum.

For over one hundred years geologists have tried to understand how these older rocks came to rest on much younger strata.

Then the succession of fossils from "old" to "young" strata is cited as "proof" of evolutionary development.

This younger strata was laid down in the Kalahari Basin underlying large parts of the centre of the country.

In general the entire package is only weakly lithified, perhaps indicating that the region was not appreciably covered by a thick package of younger strata.

There, they override the much younger strata of the plains.

It had a central axis, and bifurcated at its tips; similar fossils have been found in younger strata through to the Pleistocene.

Because rocks of Hercynian age are in most places covered by younger strata, the zone is not everywhere visible at the surface.

There is also more detailed knowledge of this era than any other because of the relatively young strata associated with it.