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fossil soils vs. paleosols



Stan Friesen wrote (1/30/97; 9:24a):

>I know of soils from as far back as the early Paleozoic,
>and there may well be Proterozoic fossil soils.

There is some murky terminology in our science here (I don't mean just 
Stan's).  I think an agronomist or "neopedologist" would disagree that 
fossil soils--that is, TRUE soils--go as far back as the mid-Ordovician, 
to before the time of vascular plants.  I have seen neopedologists in the 
field question the "soilness" of many sediments that I and paleosol 
experts would unhesitatingly call paleosols because they were clearly 
affected by certain pedogenic processes during episodes of subaerial 
exposure.  Depending on your definition, a paleosol does not necessarily 
have to be a "paleoSOIL."  Some supposed Late Ordovician paleosols I have 
seen in Pennsylvania are nothing that could be called a soil in today's 
world.  However, the evidence for subaerial exposure in those sediments 
is clear.

Just something to be aware of.


*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
Norman R. King                                       tel:  (812) 464-1794
Department of Geosciences                            fax:  (812) 464-1960
University of Southern Indiana
8600 University Blvd.
Evansville, IN 47712                      e-mail:  nking.ucs@smtp.usi.edu