68 
IOWA ACADEMY OF SCIENCES. 
The Kansan drift is thicker. It is deeply oxidized at the sur- 
face, and its granite boulders are so far decayed that the steam 
shovel has cut through individuals a foot or more in diameter 
without encountering as much resistance as is offered by the 
surroundiug clay. The sub-Aftonian contains small pebbles of 
very hard crystalline rocks, many of the pebbles being of vein 
quartz, but there are few granites. Concerning the climate of 
the Aftonian interglacial period the wood aud peat would indi- 
cate conditions similar to those that may exist in northern 
Maine. 
Iowa is now classic ground for the study of Pleistocene 
deposits, andfgeologists the world over, if they would study 
these deposits to best advantage, must come to Iowa to do it. 
ADDITIONAL OBSERVATIONS ON SURFACE DEPOSITS 
IN IOWA. 
BY B. SHIMEK. 
During the past summer the author made a series of observa- 
tions, at the request of Prof. S. Calvin, upon the surface 
deposits of the northern part of the state, the results of which 
may be worthy of record. 
Borings were made with a two and one-half inch auger 
attached to gas pipe, and in addition to this cuts along railways 
and wagon roads and exposures along creek and lake shores 
were examined. The chief observations were made at the fol- 
lowing points: 
a. At Clear Lake, in Cerro Gordo county, three borings 
were made in the timbered ridge east of the lake, as follows: 
One within five rods of the lake shore and two on the topmost 
part of the hill to the east. 
&. At Forest City the following work was done: 
1. Eleven borings were made due east from Forest City on 
the timbered ridge which extends north and south, parallel 
with Lime creek and just east of it, beginning at the top of the 
ridge north of the road, and thence at Irregular intervals for 
450 yards to the south. Nine of these borings were made at or 
near the summit of the ridge and two, one on each side, were 
made near the foot. 
