214 Mc Gee and Gall — Loss of Des Moines, Iowa. 



Des Moines and Eaccoon rivers, just as on that constituting 

 Capitol Hill, a fine, compact, superficially modified drift clay, 

 yielding a calcareous efflorescence on exposed surfaces, and 

 bearing erratic bowlders sometimes four or five feet in diam- 

 eter, was found to prevail. The finer upper portion, which, 

 notwithstanding its comparative freedom from smaller pebbles, 

 contains the largest bowlders, has been removed from a total 

 area of several acres (to be employed in the manufacture of 

 brick), leaving abundant bowlders lying on the surface. One 

 of these, of green stone, two or three feet in greatest diameter, 

 was found to be deeply striated longitudinally on two parallel 

 sides: and another, of like material and equal size, was finely 

 polished on one side. The topographical configuration is in 

 general similar to that of loss areas ; but the erosion has thus 

 far been mainly peripheral. 



Brick-clay Pit S. of cor. Jefferson St. and Indianola Av. — Alt. 845 ± 6 ft. 



1. — Light brown, coarse, friable loam, free from pebbles, massive, 

 but graduating into number 2. Three feet. 



2.— Light brown and gray strati hVd * :l nd in slightly sinuous but 

 general I v horizontal bands one-third inch thick, each mas- 

 sive. Eight feet. 



3. — Loss, blue and ashen-hlne, nhseurely laminated horizontally, 

 with rather rare loss kindchen, abundant tubelets and 

 cylindrical ferruginous concretions, and very rare fossils; 

 only fragments of Succmea and Papa appearing on hasty 



4. — Arenaceous shale of the Coal Measures, partially decomposed 

 at the summit. 



The two uppermost members form a portion of a nearly 

 destroyed terrace. A very few pebbles and two or three 

 bowlders one or two feet in diameter, probably derived from 

 them, lie about. A distinct ferruginous band apparently sepa- 

 rates numbers 2 and 3; but in reality there 

 6cation about the line of junction. Immediately below this 

 band cylindrical ferruginous concretions occur" in greatest 

 abundance. The loss is slightly silty in aspect and friable in 

 texture, as toward the base in sections 1 and 2. 



A sequence, substantially identical with that noted on Cap- 

 itol Hill and on the central plateau, was observed in two or 

 three sections near the summit of the bluff; and in S.E.N. W. 

 21, 78 N.,_ 24 W., where the surface is formed of drift, a cellar 

 centered a loss-like deposit. The topography 

 nthine, and the drift is as loss-like and calcareous as on 

 the north side of the river; but no bowlders more than two feet 

 in diameter were here seen. 



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