CompuServe Messages

A little expansion and further comment: >> There are some unusuall occurrences such as mentioned in Greg Laden's message, but generally fossils to do not get redeposited out of sequence.>> Right. It is especially important to note what we mean by "out of sequence". It is very very hard to get a deposit to form where the fossils are inverted systematically across several layers. Getting a few older ones mixed up with newer ones happens now and then, and is expected to be quite obvious most of the time. But a true inversion is extraordinarily rare. Can't think of any real good examples at the moment, as a matter of fact. << Techinically they oculd, older rocks are continuously being uplifted and eroded away and redposited as younger sediments. > Right again. This is especially true in certain environments, such as a forming rift valley (where we had so much trouble in Zaire, and as happens now and then in the East African rift as well). In the rift valleys, you can get sedimentary basons formd on grabens that are faulted, so there is, say, half the graben sitting up hill pouring stuff down onto the surface of the other half, down faulted, in a lake or stream bed. But again, this is obvious when it happens, fossils get destroyed in the process as you say, and it does not result in a true inversion. Cheers, GTL – Greg Laden, Written 20-Aug-1994 @ 19:01:50 Using: Windows NavCIS PRO 1.25