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 largely accidental attributes of 

 strata, and therefore cannot have the impeccable classif acatory 

 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 



