Re: index fossils

Norm Smith (74532.66@compuserve.com)
17 Jan 96 09:44:42 EST

I too, as Arndts, am rather on the consumer end of stratigraphic studies. I
appreciate the careful responses such as that of MacRae. I have read many
books on the subject of correlation but have been disappointed by the difficulty

of finding a carefully presented development of the basic thesis. The closest I

have found to such a development is in an older introductory textbook,
"Historical Geology" by A. O. Woodford, W. H. Freeman & Co, 1965. Some
books such as "The Chronology of the Geological Record", Geological Society
Memoir No 10, 1985, ed N. J. Snelling present correlation schemes of great
detail
but are rather lacking in a basic development of their validity. "Numerical
Dating
in Stratigraphy" ed Gilles S. Odin, Wiley, 1982 contains a good discussion of
various problems in correlation but still does not develop the basic thesis.
Thanks to MacRae for the reference to the Harland book; I will look that one up.

When looking over some of the detailed correlation schemes such as in the
above Memoir, I can't help but question to what degree is the ordering in the
eye
of the beholder. The notion occurs to one that the maximal degree of ordering
which one can impose on the actual field data and still be consistant, on the
one
hand, and the minimal degree of ordering that is inescapably inherent in the
field
data, on the other hand, may well be rather different. I have not found a good
discussion of such a notion.

It would also seem that in a careful development of this subject, one could find
a
separation between a good description of the raw phenomena one is attempting
to explain and ones explaination of that raw data. It is difficult from the
literature
to obtain a clear picture of the arrangement of the physical rock properties and

the fossil content alone. Such content is almost always described in reference
to
the standard chronology making it difficult to determine the degree to which the

described arrangement is necessated by the actual field data versus being a
reflection of the chronological scheme itself.

Anyone noticing their geologic environment can not but appreciate the enormity
of the task of describing the field data. However, the basic notions that would
be
involved in concepts of correlation do not appear too complicated to allow a
rather rigorous development if one can be made. To this observer, it seems that

there has been a rather appalling lack of a careful presentation of basic
correlation concepts by the academics in this field. I should be happy to be
corrected on this point.

Norm Smith
74532,66@compuserve.com