Ulrich—Paleozoic Systems in Wisconsin. 
73 
Cambrian beds so imperfectly indicated that the locality consti¬ 
tutes a most unsatisfactory type for the composite formation I had 
in mind when I adopted Winchell’s term for it in 1914. Second, 
the name was originally applied only to the magnesian limestone 
that lies in the lower part of the formation. The subsequent ex¬ 
pansion of the application of the name to everything between the 
top of the Dresbach sandstone and the base of the Jordan sand¬ 
stone was unwise and unwarranted by rules governing in such 
cases. Third, the name St. Lawrence, as applied to a stratigraphic 
unit, ever since its proposal in 1874 has had an uncertain status 
and meaning. At times it was referred to the Lower Magnesian 
series and then to the St. Croixan; and only very recently Keyes^ 
committed the now almost unpardonable error of correlating it 
with the Oneota dolomite of Iowa. Besides, prior to 1914, all who 
had occasion to refer to the St. Lawrence limestone made it the 
same as the really much younger Mendota limestone of Wisconsin ; 
and even today a few of the more conservative geologists adhere 
to this old opinion. As an additional and final reason I may say 
that employed strictly in its original sense there is still a desirable 
and valid use for the term St. Lawrence limestone or dolomite. It 
is almost needless to say that the St. Lawrence in the type locality 
is not, as recently thought by Keyes, the Oneota dolomite but a 
much older and thinner bed that is widely distributed, especially 
in southern Wisconsin, where it lies either at or a few feet above 
the base of the Trempealeau formation. At St. Lawrence, as very 
generally too in Wisconsin, the bed is marked by a definitely Cam¬ 
brian fauna that is entirely different from the Upper Ozarkian 
fauna which is found in the Oneota dolomite. 
Judging from the varied and usually critical comments made 
by geologists who have kindly read the original draft of this 
paper it seems desirable and perhaps necessary to give a fairly full 
account of the nomenclatural history of the term St. Lawrence 
limestone and of the very different meanings in which the name has 
been used by authors since it was first proposed by Winchell. This 
account will at the same time serve in determining the relations 
of the real Jordan sandstone to other sandstones with which it has 
been confused and of the Franconia formation to the St. Lawrence, 
the “Sparta Shale,’' and other formations that have been named 
in the past ten years. 
^ Keyes, Charles, Terranal differentiation of Iowa Cambric succession, The Pan- 
American Geologist, vol. 38, No. 4, p. 323, 1922. 
