102 The Amenca?i Geologist. February, i90(t 
ratlier a hollow — and here are the figures as given by the man 
who dug the well, describing the different soils as they came: 
Feet 
I ■ Black loam 3 
2. Crumbly yellow' clay 14 
3. White material 3 
4. Tree 9 
5. Blue clay 6 
"This is on Mr. J. D. Foley's place, section thirty-five. 
Spring Valley tov/nship, six miles from Bradley; there are 
others similar." 
The white material is evidently a white marl. It contains 
Valvata tricarinata, Planorbis bicarinatus, P. parvus and Lim- 
nea humilis. Miss Buzzell sent numerous pieces of wood, most 
of which I judged to be coniferous. They show the charac- 
teristic tracheids and resemble tamarack. Specimens of muck. 
No. 4, contain fresh water shells similar to those in No. 3, and 
also Anadonta and Spoerium sulcatum. The data are not suf- 
ficient for asserting that this deposit is interglacial. It may 
result from the filling of a recent lake basin. If such is the 
case, it resembles the locality north of Grand View, in Douglas 
county, which was described in Bulletin No. t. of the South 
Dakota Survey, page 126. Both localities are inside the Alta- 
mont moraine. 
Conclusions and Siiggestions.-Yxova the data given, we seem 
justified in concluding that there had been considerable deposi- 
tion of till over the region of the Big Sioux valley, previous to 
the occupation of the Altamont moraine of the Wisconsin 
epoch. The readiest explanation, perhaps, is that the ice 
sheet spread over all the region mentioned, although it seems 
not improbable that the comparatively pebbleless till which has 
been observed at Sioux Falls and east of Canton, may have 
been deposited by marginal waters. While occasional bowl- 
ders are found they are by no means as numerous nor as large 
as in the Wisconsin till. From the comparatively driftless re- 
gion about Garretson and the direction of the striae west of Pal- 
isades, we can scarcely doubt that the valley of the Big Sioux 
was occupied by a lobe of ice but that there were patches east 
which were comparatively stationary. 
