Faunal Aspects of tlic Original Kinderkook. — Keyes. 317 
When he has found out what are the geological units or 
terranes, and their relations to one another, he cares little or 
nothing about what biotic age is assigned. He has in his pos- 
session the skeleton frame-work which he can, at his leisure, 
clothe with flesh and blood. No subsequent finding of "Devo- 
nian" fossils in one part, of "Carboniferous" forms, in another, 
or even "Tertiary" species underneath all will change the as- 
certained relative position of his units. The disputes in regard 
to exact "geological age," according to a standard that he no 
longer recognizes as infallible or essential, concern him little. 
If the question of "geological age" or rather "biotic age" is 
approximately satisfactory so much the better. If not, strati- 
graphic work can go on without interruption. Any questions 
as to this criterion or that, are left for those who -have more 
time than he to answer. 
In geological correlation in general the tracing by visible 
continuity of the various terranes is the only absolute method 
of procedure. This ideal state of affairs is, in practice, quite 
limited in extent. Problems have usually to be worked out by 
other methods. The biotic methods have been widely used; 
but of late years more rapid and more certain results are ob- 
tained by other means. 
Instead of placing entire reliance on one general method 
the stratigrapher follows chiefly the method best adapted to 
the local conditions. Consequently the old methods of litho- 
logical similarity and similarity of lithological sequence, when 
rightly applied, have a wider and more exact bearing in the 
solution of correlative problems than, for example, many com- 
parisons of local faunas or floras. 
In the consideration of the various members of what has 
been called the Kinderhook formation along the Mississippi 
river, opinion has always been divided as to whether the pre- 
vailing aspects of the faunas were Devonian or Carboniferous. 
Hall, who 40 years ago referred the beds in question, and the 
Burlington section in particular, to the Devonian, never found 
reason to give up this idea. In the main, however, and in the 
absence of any direct inquiry, the Kinderhook of the Mississip- 
pi river region has long remained as a part of the Carbonifer- 
ous. 
It was the unsatisfactory state of the problem that led re- 
