STRATIGRAPHIC GEOLOGY 347 
remote from the real one. The recent report on Monroe county, 
the southeastern one of Michigan, by the Geological Survey of that 
state, has added greatly to our exact know ledge of this formation. 
The writer has “also collected considerable data in this state, 
Michigan, Ontario, and New York for a bulletin upon this for- 
mation. The “Corniferous limestone” is composed of the two 
distinct formations of the Columbus and Delaware limestones 
which have never been separately mapped. It may be mentioned 
in passing that Dr. Charles K. Swartz of Johns Hopkins University 
has in preparation a valuable monograph describing the strati- 
graphy and paleontology of these formations and the writer and 
his students have done something in this same line. The next 
large division, the ‘“Waverly Group,” ” in central Ohio, is composed 
of six clearly defined formations, viz.: the Bedford shale, Berea 
sandstone, Sunbury shale, Cuyahoga, Black Hand and Logan for- 
mations, no one of which has ever been mapped separately. It is 
also probable that there will be some change in the units of this 
series in the northern part of the state and perhaps in the southern 
as compared with those of central Ohio. The writer and his 
students have given considerable attention to the problem of the 
classification and description of the Waverly series. Finally, the 
area colored as the “‘Coal Measures” includes the upper portion of 
the Pottsville, the Allegheny, Connemaugh and Monongahela for- 
mations together with the Dunkard formation, the latter probably 
of Permian age. Although these formations are not mapped 
separately, still something has been done toward furnishing the 
data for such representation in tracing the various coal seams 
of the state. Certain ones, as for example the Upper Freeport, 
Pittsburg and Waynesburg coals indicate formation limits and the 
recent work of Dr. Bownocker and his assistant in tracing the 
Pittsburg coal will be of value in separating the Conemaugh and 
eee formations. There also remain the subjects of 
glacial and physiographic geology which have become of great im- 
portance and interest in these later years. Concerning elacial 
geology much has been accomplished by the United States Geo- 
logical Survey in this state as is shown in Leverett’s Monograph 
entitled “Glacial formations and drainage features of the Erie 
and Ohio basins.” 
It is not the writer’s intention to criticise In any way the work 
of the earlier members of the Ohio Geological Survey, and if any 
have formed that opinion they have missed entirely the aim of this 
paper. Indeed, on the contrary, he often wonders at the large 
amount of correct and valuable information which they brought 
together, hampered as they were financially, pressed for time, and 
often laboring under most discouraging conditions. The fidelity, 
perseverence and faithfulness of those men merit all honor. 
Neither has the writer any criticism to make of the present 
