IOWA ACADEMY OF SCIENCES. 
141 
that it is the same the world over, than are the claims of the 
old Wernerian ideas of general sequence, based upon litholog- 
ical similarity. The element of error is identical in both. It 
is an assumed premise. Both the lithological and faunal 
characters must be regarded as largelj^ accidental attributes of 
strata, and therefore cannot have the impeccable classifacatory 
values once ascribed to them. 
The formulation of the weakness of fossil criteria in general 
correlation may be passed over here. They are fully noted in 
the conclusions of Huxley, Irving, Van Hise, McGee, Walcott, 
Brooks and others. The very basis of the method is highly 
variable, in the same way as that of lithological character. 
The preeminent position which paleontology has long held 
in geology, has been in great part due to its biological rela- 
tions, or environment. It has formed one of two chief lines of 
inquiry into one of the most important and most absorbing 
philosophical questions of the century. So overpowering has 
been its influence in stratigraphy, that it even has been urged 
that there can be no scheme of geological chronology which is 
not based upon it. As a science, paleontology had its rise in 
geology, though it is really a department of biology, and the 
vast expansion that it has undergone still closer welds it to 
the latter science. The whole tendency of its development, of 
late years, has been towards the biological side. Its use, in 
strictly geological work, has become more and more restricted 
and overshadowed by the physical sciences which offer a 
broader foundation. Without the slightest disparagement to 
its good offices in the past, it may be said that it can never 
have the exalted place in geology that it once had, though it 
will ever be of use in practical local stratigraphy, especially 
when taken in connection with other data 
Another reason why paleontology long had such an unpre- 
cedented influence upon geology is that it was so thoroughly 
permeated with pre- Darwinian ideas of repeated creations and 
of sudden extinction of species and faunas. Hence no cor- 
relations, either local or over broad areas, have ever been 
precise, apparently, nor, in the absence of facts to the contrary, 
has the equivalencies of strata widely separated geographically 
been determined so positively, as those made out a generation 
or two ago. Even to-day geological correlations rest practi- 
cally unchanged on these manifestly insecure foundations. 
Since the beginning of the present century, when William 
