92 Wisconsin Academy of Sciences, Arts, and Letters. 
thickness (2 to 15 feet) that contains some magnesian limestone 
layers with dismembered plates of crinoids or cystids and other 
fossils that is recognized as far south as La Crosse. At this latter 
place, however, it rests on the initial Franconia deposit of re¬ 
worked Dresbach sand containing Camaraspis convexus (Whitf.). 
At Hudson, on the contrary, it is underlain by about 27 feet of soft 
sandstone more or less profusely charged with greensand; and this 
ought to correspond to the “Lower Green sand” of the Sparta 
region. Granting this decidedly questionable conclusion it would 
follow that the “Micaceous shale” of the Sparta region is unrepre¬ 
sented in the sections at Hudson and elsewhere in the area to the 
north of La Crosse. It would follow also that the lower half of the 
Franconia contains two distinct limy zones, the one in the north 
containing crinoidal fragments and lying above the ‘ ‘ Lower Green¬ 
sand,” the one in the south without crinoidal remains and occur¬ 
ring beneath or at the base of the “Micaceous shale.” But these 
doubtful correlations can as yet be viewed only as provisional sug¬ 
gestions to be entertained until proved or disproved by the results 
of detailed comparisons of sections and fossils now being carried on. 
At present it seems more probable that the limy zones are the same 
and that the “Lower Greensand” of the south, rather than the 
^ ‘ Micaceous bed, ’ ’ thins out or becomes unrecognizable to the north. 
As in southwestern Wisconsin, so also in the sections at Fran¬ 
conia, Minn., Hudson, Durand, west of Mondovi and as far south 
as Trempealeau in Wisconsin, the base of the Franconia is made 
by a fossiliferous bed that consists mainly of reworked Dresbach 
sand. But in the mentioned latter places the initial Franconia 
deposit contains more glauconite. Its fossils also are quite differ¬ 
ent from those found in the basal Ironton sandstone member of 
the formation in the southwestern quarter of the State. In the 
latter region the fossils in the basal sandstone consist almost en¬ 
tirely of trilobites, most of which have been found only in this 
bed. On the other hand, the fauna of the basal sandstone in the 
mentioned northern localities consists entirely of a few species of 
inarticulate brachiopods. Of these brachiopods a species of Dicel- 
lomus, usually referred to D. politus —a common fossil in the Eau 
Claire shale—is most abundant. A small elongate and very narrow 
species of Lingulella is more characteristic of the zone. 
These regional variations in the composition of the lower third 
or half of the Franconia, when all is considered, can be interpreted 
only as indicating differential oscillation of surface and conse- 
