:5H2 
Tlie American Geolof/isf. 
May, 1897 
I have thought it preferable to ado])t a local classill(uition 
that can be kept free from such shifting opinion, while at the 
same time admitting the approximate correlation of each part 
with certain prior established geologic formations of other 
areas. Since this provisional classification, if you will, was 
given to publication, the latest work by Winchell and Ulrich 
has been published, but ver}^ evidently it was in press at the 
same time as my own (loc. cit.) and therefore no attempt to 
compare the two classifications could have been made by them. 
The first half of their discussion had been published, in fact, 
in part i of the volume, and on page 1, a table of formations 
shows nearly their final revised system of designations, the 
r;nisons for the position of which are, however, given only in 
part II, which is just published. To include their classification 
in my discussion of the Galena and Maquoketu series was not 
practicable until now, because the argument for its presenta- 
tion was yet unpublished. 
Hudson River 
OR 
Cincinnati. 
Richmond 
linieHtonc. 
Wykoff 
forriKitioii. 
Maquoketa 
SERIES. 
Uticn shale. 
Maquoketu. 
formation. 
(Not Defined.) 
Transition 
formation. 
Trenton. 
Trenton. 
Galena. 
Galena 
SERIES. 
Black River. 
Beloit 
formation. 
Stones River. 
Messrs. Winchell and Ulrich have replaced, as far as possi- 
ble, all original names by others that are derived from corre- 
lation. Their paper is one of the most important on the sub- 
ject that has been written and although I cannot here discuss 
the merits of their correlation, it will be worth the while to 
compare their classification with the local classification which 
I have recently outlined, in order to show the true relation be- 
tween the original names and those derived by correlation. 
