382 The Aitierican Geologist. 
June, 1899 
chiefly by impact and a fixing of the dirt particles by the un 
even surface of the snow and other obstructions. . 
During last spring the writer, while on the Ozark plateau 
in southern Missouri, experienced several similar storms of 
fine dust. One equal in prominence to the recent one in the 
Northwest, followed a severe blizzard. One morning the 
snow was found to be discolored by an impalpable dust of a 
dark brown color, and the atmosphere was still so heavily laden 
with dust that objects one-half mile distant were invisible. 
During this storm the cold was intense for that latitude, there 
was no fall of snow and the atmosphere perfectly free from 
clouds except the peculiar brown dirt-clouds. If the wind 
maintained the same, direction from the area in which it gath- 
ered up the dust, which it had when observed, the origin of 
the material may be referred to central Kansas. 
In the early part of April a heavy southwest wind brought 
a similar duststorm into the district. It was terminated by 
rain, which apparently precipitated it, completely clearly the 
atmosphere near the earth. After the rain, which was of the 
fine, drizzling variety, the sky remained cloudy for eight hours. 
The clouds were broken and comparatively high. /Vmong the 
white aqueous cloud masses there were frequent appearances 
of similarly shaped clouds of a buff color. The latter were 
undoubtedly bodies of disseminated dust, which had been car- 
ried up into a higher stratum than that next the earth and 
passed over this district in the same manner as the ordinary 
clouds. The contrast between the two colors of clouds was 
strong and gave the sky a checkered appearance which is not 
very often seen. The direction of the wind pointed to an 
origin of the material from the prairies of northern Texas and 
southern Oklahoma. 
The bearing of the preceding facts on some of the theories 
advanced in explanation of the recent "Black Snow" of Chi- 
cago and vicinity is obvious. The dust was gathered up from 
some remote district of the Northwest, carried by the violence 
of the wind, like sediment in a current of water, across hun- 
dreds of miles of snow covered country, and precipitated about 
Chicago, in conjunction with, but not as the result of, a fall 
of snow. 
Freeport, Illitwis, Feb. 20, i8g6. 
