Ulrich—Paleozoic Systems in Wisconsin. 
91 
Finally at the base of the formation is a 2 to 15~foot bed of 
reworked Dresbach sand. Usually this forms a single massive ledge 
and bench at the top of the Dresbach bluffs^ commonly holding this 
position because its top is more or less silicified and therefore more 
resistant than the relatively incoherent mass of sandstone beneath 
it. It contains some highly characteristic fossils which distinguish 
this initial deposit of the Franconia from all preceding and suc¬ 
ceeding beds in this region. Some of the more useful of these fossils 
are mentioned on a following page. 
Of these five members only the lowest and possibly the shaly 
micaceous bed above it are clearly recognizable by their respective 
lithologic and faunal characters in the Franconia as developed in 
the tops of the mounds in Adams County. In these mounds the 
soft greensand members are represented, as is clearly established 
by their fossil contents, by much harder red and gray sandstones; 
but the intervening yellowish sandstone member is not easily dis¬ 
tinguished from the beds on either side of it. However, the sand¬ 
stones that are believed to correspond to the upper part of the 
intermediate member form unusually massive, coarsely grained and 
but sparingly fossiliferous ledges. 
In the northwestern quarter of the State, speaking particularly 
of the area between Mondovi and Alma on the south and St. Croix 
Falls on the north, no two of the many Franconia sections are 
strictly alike. And yet a general similarity in both the character 
and the sequence of the beds is manifestly maintained. Compared 
with the Franconia in the southwestern quarter only one of the 
members usually determinable there is clearly identifiable in the 
northwest. The zone referred to is the yellow sandstone member. 
In places, particularly in the area between Hudson and Menomonie, 
this member maintains in fair approximation the color and char¬ 
acter of bedding that distinguish it in the region between Sparta 
and Lavalle. However, followed from Hudson both to the north, 
as at Franconia, Minn., and to the southeast, as in Beef Eiver 
valley between Alma and Mondovi and also at Durand, nearly the 
whole of this member becomes so strongly charged with glauconite 
that were it not for its abundant and highly characteristic fossil 
contents it would hardly be distinguished from the associated green¬ 
sand beds. 
In the northwestern quarter of the State there also, is a fairly per¬ 
sistent “Lower Greensandzone. At its top is a bed of variable 
