Coal Measures of Kansas. — Kcyes. 347 
CORRELATIVE RELATIONS OF CERTAIN SUBDI- 
VISIONS OF THE COAL MEASURES 
OF KANSAS. 
By Charles R. Keyes, Des Moines, Iowa. 
During the lustrum just past, unusual activity has marked 
the geological investigations of the coal-bearing formations 
of the Western Interior basin. The entire area has been 
more or less carefully examined anew. The stratigraphy of the 
whole district may now be considered as being fairly well un- 
derstood according to the modern principles of geological cor- 
relation. All the states within the limits of which this coal 
basin extends — Kansas, Nebraska, Iowa, Missouri, Arkansas, 
and Indian Territory — have made noteworthy contributions to 
our knowledge of the subject. 
Most of the earlier investigations were either of the char- 
acter of rapid reconnoissances, or they were limited by state 
borders. Little opportunity was offered for comprehensive 
examinations unrestricted by political boundaries. The scien- 
tific work done was usually state work. Each state had to 
set up standards of its own. In consequence, it has not al- 
ways been beyond doubt just what were the exact relations 
between the subdivisions recognized in one state and those 
of another. Even in dififerent parts of the same state the 
stratigraphical equivalency of the various coal beds could not 
be more than approximately surmised. 
(jf late, much has been done to completely change this 
condition of affairs. We may now be regarded as being in 
possession of the necessary data to enable the various correla- 
tions to be made with measura])le accuracy over the entire re- 
gion. 
It is now nearly half a century since the earliest pioneer ' 
work in geology was done in this region. While all of it was 
carried on in a more or less disconnected manner there is 
much of it that was accomplished with a surprising degree of 
accuracy, that is of lasting value, and that will always possess 
a peculiar interest. 
From the literature alone, it is not always, without con- 
siderable difficulty, that these early results can be compared 
with the later; but, when once reviewed in the field, the astute- 
ness with which many of these first observations were made 
