78 Wisconsin Academy of Sciences, Arts, and Letters. 
ary. Evidently it was drawn somewhere about the transition 
from the limy Lodi shale member to the Norwalk sandstone mem¬ 
ber of the Trempealeau formation, this position being indicated by 
the thickness (160 feet) assigned to the overlying ‘^Jordan” sand¬ 
stone and the fact that in the columnar sections the St. Lawrence 
is extended only to the top of the limy beds. 
Even if the St. Lawrence formation as defined in these Water 
Supply Papers were a naturally bounded and permanently desir¬ 
able stratigraphic unit I see no warrant for this expansion of the 
St. Lawrence except the suggestion by Winchell in 1888 and the 
paper by Hall and Sardeson, both of which are referred to above. 
But Winchell himself failed to carry out his suggestion, and Hall 
and Sardeson did so under obvious misconceptions as to the corre¬ 
lation of the concerned beds. Besides, the lower part of the ex¬ 
panded St. Lawrence had in the meantime been named by Berkey; 
and after the term Franconia sandstone had been proposed all 
possible excuse for extending the application of the name of the 
superposed smaller and in every respect less important strati¬ 
graphic unit so as to cover and completely eliminate Berkey ^s 
Franconia had been forfeited. Moreover, experience in the field 
has proved conclusively that the lower two-thirds or more of Hall 
and Norton ^s St. Lawrence formation—in other words, the Fran¬ 
conia—is as useful and as clearly defined a formation as any of 
the subdivisions of the Upper Cambria series in the Upper Missis¬ 
sippi Valley now recognized. 
In 1914, two years after the appearance of Norton’s paper, Wal¬ 
cott® published the sequence and preliminary classification of the 
Upper Cambrian formations in Wisconsin and adjoining States to 
the west that had been worked out the preceding field season by 
E, 0. Ulrich, In this classification the Franconia is recognized and 
the St. Lawrence formation of Hall and Norton was not only re¬ 
stricted to beds above the Franconia, but its definition was again 
modified by extending its upper boundary so as to include a sand¬ 
stone—^here distinguished as the Norwalk sandstone member—that 
had been improperly referred to the lower part of the Jordan 
sandstone by the Minnesota and Iowa geologists. The Norwalk 
sandstone member is not present in the section at Jordan, Minn., 
but where both are found, as is generally the case in western Wis¬ 
consin, the two are usually separated by a well-defined boundary. 
® Smithsonian Mis. ColL, vol. 57, p. 354, 1914. 
