IOWA ACADEMY OP SCIENCE 
153 
OROTAXIAL GEOLOGIC CORRELATION AND DIASTROPHISM. 
BY CHAELES E. KEYES. 
Exact stratigraphic correlation is today bothering the geologist more than 
any other subject relating to earth knowledge. This phase of geology has, 
indeed, been a constant source of embarrassment ever since the science’s birth 
more than a century and a half ago. A hundred years ago William Smith, an 
English engineer, discovered the use of organic remains in the determination 
of the relative ages of rocks; and since his time fossils have been very gener- 
ally depended upon in unravelling the geologic history of the various parts qf 
the globe. 
During the last quarter of the last century stratigraphy began to demand 
quantitative, instead of merely qualitative, results. Other stratal criteria of 
a critical character were found to be, in the field, of even greater practical 
value than the fossils could ever hope for. At the present time most of the 
geological surveys have adopted a lithologic standard for the geologic unit in 
mapping; and the fossils come to have only a secondary importance, or are 
ignored altogether. Even this scheme has not proved to be so satisfactory as 
was anticipated. It is now quite manifest that we shall have to seek more 
fundamental criteria in the interests of exact geologic correlation. We shall 
have to look more carefully into the factors which control sedimentation, which 
modify it, and which delimit the geologic terranes. 
Every classification of natural objects is very simple and very perfect so 
long as we make no comparisons with other methods and do not adopt any 
other criteria. For example, we may classify plants by means of their fiowers; 
or by their leaves. We may arrange systematically the mammals according 
to their teeth. So, also, we may construct an elaborate stratigraphic scheme 
in accordance with the contained fossils and have, to all appearances, not only 
a complete but a seemingly flawless plan. This for the last hundred years the 
paleontologist has tried to impress upon us. It is, however, a classification of 
organic remains and not necessarily of geologic formations. 
When we make comparisons with other standards, which seem equally 
critical, the shortcomings of the paleontologic method become alarmingly 
glaring. When closely examined the paleontologic scheme of geologic classifica- 
tion is found to be not a classification of terranes at all, nor a logical arrange- 
ment of historic events, but merely a rather imperfect grouping of faunas. The 
question arises whether in stratigraphy we should not be better off today if 
we were to ignore the fossils altogether, or recognize them only in the most 
general way. 
At the meetings last winter in Baltimore of the American Association for the 
Advancement of Science, and of the Geological Society of America, there was 
