168 IOWA ACADEMY OF SCIENCE 



2. Loess, light buff, somewhat sandy and pebbly above, con- 

 taining numerous loess-kindchen, tubelets and fossils. 

 Six feet. 



The formations above the loess, as described by McGee, are 

 not visible at present, as they have been in part concealed, in 

 part removed, by later building operations. However, on the 

 south side of Court avenue, between 10th and 11th streets the 

 following section is revealed and must lie below McGee 's sec- 

 tion : 



1. Loess, yellow with gray spots and streaks and masses, 



especially where rootlets have penetrated. Ferruginous 

 "pipe stems" are quite numerous in the gray portions of 

 the loess. No fossils were seen in the lower three or 

 four feet, but above this zone they are quite abundant, 

 in places to the top of the exposure. No kindchen were 

 seen in this exposure. The lower foot of the body of 

 loess grades down from yellow to reddish brown with 

 gray streaks. In one place a four inch band of finely 

 jointed reddish clay with starchy structure lies four 

 inches from the base of the loess. It contains some 

 small sandstone pebbles and extends along the face lor 

 a few feet. Apparently the loess is all one body. The 

 great mass, with the exceptions noted, is uniform from 

 top to bottom in co'or, texture and general appearance. 

 Fifteen feet from level of 11th street. 



2. Geest, residual from Coal Measures shale; reddish brown, 



sticky clay containing small pebbles of sandstone and 

 shale. Contact with loess above sharp, no gradation. 

 One foot near 11th street, thicker near 10th street, where 

 cover is thin. 



3. Coal Measures shales, red, purple, blue, green, one to three 



feet; succeeded by solid bed of light blue shale, with a 

 two inch band of black shale six feet below the top. 

 Exposed fifteen feet to grade at 10th street. 



The upper surface of the geest is practically horizontal, while 

 the ground surface slopes to the west toward the Des Moines 

 valley bottoms. Hence the loess thickens from a thin veneer 

 at 10th street to fifteen feet at 11th street. A number of years 

 ago an excavation above the level of 11th street revealed about 

 six feet of gray loess with "pipe stems" and concretions. 

 Still farther back from the present exposure the surface rises 

 about ten feet and probably the loess here is overlain by drift- 



Another section on the south side of Court avenue midway 

 between 11th and 12th streets is representative of the material 

 along this part of the cut : 



