344 The American Geologist. June, 1891 
gests the bottom of a swamp. In the lower part of the dust there 
are vertical holes and impressions of round and triangular stems and 
V-shaped leaves or sedges that evidently were slowby buried under 
the falling dust. Mere shreds of these plants remain in the empt}* 
moulds, but in some of these there are siliceous skeletons of fresh- 
water algae, which must have become entangled on the stems of the 
sedges. The water cannot have been deep at this place, when the 
dust fell. Above the hight to which the impressions of the buried 
vegetation extend, the deposit becomes ripple-bedded. Evidence 
of the rocking motion of the not very distant surface-waves of the 
water is also seen in the formation of pills, somewhat resembling 
pisoliths, which are found imbedded in the dust and must have 
been rolled together by the waves. There can be but little doubt 
that the surface of the water was within a few feet of the top of 
this deposit, when it was formed. If such was the case and if 
the locality does not represent an old isolated pond, as does not 
appear likely, then it furnishes a clue to the relative hight of the 
water level at the time of the falling of the dust. In such case 
it is certain that the water presented an expanse several miles 
wide in the trough described, and this must have been confluent 
with another and still wider body of water in the Smoky Hill 
river valley to the north. The Cretaceous buttes to the east and 
to the north were not submerged, and to the north-west the same 
rocks must have formed a considerable stretch of land, even if 
allowance is made for a subsequent tilting of eight feet per mile 
to the east. 
The top of the volcanic dust gradually changes to a buff- 
colored loam, which in man}' places resemble loess. It is rich in 
carbonate of lime, which often forms concretions. It varies in 
coarseness from that of fine sand to coarse cla}", and sometimes 
acquires a drab color. The thickness of this deposit is greatest 
in the middle of the trough, but it extends over the borders of 
this, and though often modified b}^ the action of wind and water, I 
think it may be regarded as a remnant of the latest general 
deposits of the plains in this region. * 
*I suspect that this is the same as the " loess-like " formation in Ne- 
braska described by F. W. Russell in the American Geologist for Jan., 
1891, and that it is related to the lake sediments spoken of by Dr. L. E. 
Hicks in his paper on "An Old Lake Bottom," (See Bull. Geol. Soc. Am. 
Vol. 2, p. 25, etc.) The peculiar topography described in this paper is 
duplicated on a smaller scale in the lakes and basins of MePherson 
county. 
