■ ‘Geologic correlation 249 
FOUNDATION OF EXACT GEOLOGIC CORRELATION. 
CHARLES KEYES. 
In the last generation or two there appears to have been 
little advancement made along lines of general geologic correla- 
tion. Two controlling reasons stand out prominently. On ac- 
count of the fact that the criterion of fossils is so largely mis- 
used and is so generally unchecked by other critical criteria it is 
continually losing much of its former precedence. The adop- 
tion of the lithologic formation as the cartographic unit is 
also almost a complete failure for the reason that no account is 
taken of the change, replacement and effacement of its essential 
characters from place to place. All this confusion^ gives rise to 
an interminable syponymy which even a specialist in a circum- 
scribed region cannot always satisfactorily make out without de- 
tailed review of the original sections on the ground. 
When the mania for proposing new titles for geologic forma- 
tions becomes so acute as it has in the case of the collector of 
fossils there is little real hope of simplifying stratigraphy so 
that the average worker going into a district may easily un- 
derstand, and without undue expenditure of time and effort, 
acquire fundamental insight into the problems presented. In 
the last quarter of a century there appears to be not a single 
systematic effort on the part of the geological surveys of the 
country to accomplish what should have been done years and 
years ago. Instead matters in this respect are growing rapidly 
worse instead of better. In no field of science is there presented 
so chaotic a state of nomenclature as that relating to stratig- 
raphy. 
In casting about for the proper area for which to construct 
a suitable generalized section of local rocks the quadrangle as 
ordinarily selected appears to be much too small to be of any real 
service. The county is likewise too limited in extent. In size 
the state seems most satisfactory for trial-tests in continental 
correlations. A comprehensive section of the Iowa rocks was 
given last year in the Proceedings of the Academy. This year 
a similarly constructed section of the Missouri rocks is annexed 
for comparison. Later, sections of Kansas, Oklahoma, Western 
