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IOWA ACADEMY OF SCIENCES 
silt widely and rapidly, as was so well exemplified in the fiood of 1881 
in the Missouri River (See Report of Mississippi River Commission, 
1881, p. 136, and Bull. G. S. A. Vol. 12, p, 489.) This lacustrine stage 
was attained even with . a greater slope than that of the stream at low 
water. 
Similar lacustrine conditions obtain more or less in the deposition 
of the loam capping bottom lands generally. The more perfect the 
lacustrine character and the more rapid the deposition the more mas- 
sive, or unstratified the character of the deposit. 
Some cases of this action in a small way in Mills Co. will be found; 
Plates VI. and V. Vol. XIII, Iowa Geol. Survey. The terraces of the 
Glacial epoch are heavily capped with loam indistinguishable from 
loess. This is particularly true of high terraces of the Missouri above 
Pierre where the loam is sometimes 30 feet thick. It appears on several 
terraces, high and low, at Pierre and many points below (See Bulletin 
158, U. S. G. S. p. 137.) also (Missouri Geological Survey, vol. X, p. 135.) 
The southern part of Sioux City south of the Stock Yards and east 
also is evidently a terrace judging from its topography. Here the 
bulk of it is loess resting on a base of coarse sand and is almost cer- 
tainly of river deposition and yet indistinguishable by structure and 
composition from the higher loess further northeast. Similar relations 
occur at Kansas City, not to mention others. 
At St. Joseph, Mo., the loess hill southeast of the depot is probably 
also a remnant of a terrace judging from its altitude and its coarse 
stratified base. The high loess around the water works is more likely 
to be of aeolian origin at least above. These localities are finely illus- 
trated in Miss Owen’s papers in American Geologist, April, 1904 and 
May, 1905. 
An important feature of this relation, which should not be over- 
looked, is the not very infrequent interstratification of the coarse and 
fine material, sometimes for the thickness of a few feet. It shows 
more or less in nearly all river terraces. Similar mingling of coarse 
material with the lower portion of the loess has been reported from 
many localities, by many observers. Winchell from Minnesota, McGee 
from northeastern Iowa, and Udden from southwestern. The writer 
has noticed it repeatedly in South Dakota and Nebraska. The inter- 
esting case of interloessial till found by Dr. Bain and the writer in 
northwestern Iowa though somewhat different, attests just as strongly the 
deposition of a portion of loess at least in water (Iowa Geol. Survey, 
Vol. V. p. 284. Proc. I. A. S. II. 20-23.) Prof. Shimek’s strictures must 
miscarry until he can find a mass of till from which the case shown 
in the plate could have slipped. And the writer feels fully as confi- 
dent as Bain expresses himself, that it is as high as any till in the 
vicinity. Moreover the plate itself shows no sign of slipping. 
But the higher loess, i. e. that which reaches up to the higher levels, 
not limited by any terrace relief, also sometimes rests upon deep de- 
posits of gravel and sand, as found above Council Bluffs a few miles 
at Mynster Spring, and north, also near Hinton station south, and 
north of Omaha, west. 
