30 Tlie American Geologist. January. 1003. 
of the ice-sheet, which probahly (hffered from that of the Alal- 
aspina glacier by liaving; commonly neither trees, grass. noi- 
any vegetation, the gales in dry weather could gather much of 
this very fine silt, sweeping it off high in the air to be deposited 
far away with the other interfluvial loess. It should also be 
added that this silt mantle doubtless includes some contribution, 
most considerable westward, of dust from the great western 
plains, this part being not of glacial origin. 
According to the well known investigation and report of 
Humphreys and Abbot, the silt deposited annually by the Mis- 
sissippi beyond its mouths and on its delta and swamp lands 
would cover a square mile to the depth of 315 feet. In a 
thousand years, therefore, at its present rate, the river deposit 
at and near its mouths would be equal to the measure of a 
thousand miles in length, two miles in width, and nearly 160 
feet in depth. During the rapid glacial melting of the lowan 
stage, however, we may reasonably suppose that the mean 
annual volume of the Missouri and Mississippi was twice or 
three times as great as now. its floods being prolonged through- 
out the summer; and the amount of >ilt gathered from the melt- 
ing ice-sheet may have averaged fivefold, I believe, or per- 
haps for some centuries even tenfold, more than the present 
supply. It seems therefore, by comparison with the work of 
these great rivers now, that they were competent, when the 
Champlain subsidence favored rapid melting of the ice, with 
an abundant supply of silt and very gentle slope of the stream 
courses beyond the ice border, to deposit the valley loess in 
the manner and time here indicated. Afterward, too, when 
the region was somewhat reelevated as at present, it is evident 
that the reexcavation of the valleys would require only a few 
thousand }'ears to deepen them, as before the moraine-forming 
Wisconsin stage, to levels below the bottomlands of today. 
My principal motive for this study of the loess comes from 
the discovery, in February of last year, by the Messrs. Con- 
cannon in a tunnel cellar on their farm near Lansing, Kansas, 
of a human skeleton beneath the lower part of the valley loess 
of the Missouri river, as I regard the geologic section there.* 
* Am. Geologist, vol. xxx, pp. 135-1,50. with two plates, Sept., 1902. The 
same number also contains, in pages 189-194, an editorial article on this sub- 
ject, bv Prof. N. H. Winchell, including notes on the Lansing skeleton by Prof. 
S. W. Williston. 
