450 
Joumal of Agricultural Research 
Vol. XXIX, No. 9- 
SUMMARY AND CONCLUSIONS 
The present paper describes and dis¬ 
cusses the third of four dustfalls known 
to have occurred in this country within 
the past six years. Two dustfalls have 
already been reported by the writers, 
(11, 12), and analyses are under way 
for a report upon the fourth. The 
physical, chemical, mineral, and vege¬ 
tal composition of the dustfall of Feb¬ 
ruary 13, 1923, is discussed in con¬ 
nection with that of other dustfalls 
of this country and abroad, and tabular 
analyses are presented. 
Dustfalls are comparatively rare, and 
have always occurred in association 
with storms of late winter and early 
spring marked by unusually violent 
winds in the arid and semiarid regions 
of the plains, the Rocky Mountains, 
and the southern plateau of the United 
States. 
The close similarity of composition 
of atmospheric dust to loess, and the 
divergence of such dust from other 
types of soils, suggest very strongly 
that the two are identical. The dust¬ 
falls of 1918 and 1920 showed on chem¬ 
ical analysis a higher content of soluble 
alkalies than is found in loess. Inas- 
mush as the dust-bringing storms came 
in those instances from the arid south¬ 
west, it may be that they furnish the 
primitive material from which the loess 
has been formed. In 1923 the scene 
of deflating winds was closer at hand, 
and the coarser composition indicates 
that the atmospheric dust had been 
transported a slighter distance, per¬ 
haps from the region of the Missouri 
valley, where loess deposits are deepest. 
The great depth of the deposits of 
loess, amounting to hundreds of feet 
in some places in the States of the Mis¬ 
souri Valley, compared with the present 
slow rate of deposition of atmospheric 
dust, indicates that dust-bearing storms 
were probably more frequent in the 
period when the loess was laid down. 
That could have been accomplished if 
the weather of the glacial period had 
been more continuously like our present 
February and March weather. At the 
same time there must have been exten¬ 
sive areas in the Southwest, uncovered 
by vegetation, from which the finer soil 
particles could be blown away by the 
wind. The fine size of the loess com¬ 
ponents indicates that they had been 
carried long distances by the wind r 
rather than obtained by deflation in 
the vicinity of deposit. 
The presence of viable spores of 
plant disease in association with atmos¬ 
pheric dust which has been transported 
hundreds and even thousands of miles r 
indicates that such diseases may be 
rapidly spread over longer distances 
than plant pathologists have hitherto 
considered possible. 
A peculiar psychological phenome¬ 
non associated with dustfalls is the fact 
that scarcely anyone notices them. In¬ 
quiries broadcasted during and after a 
dustfall elicit surprisingly few positive 
responses. But the complete study of 
such widespread phenomena as dust¬ 
falls demands more extensive atten¬ 
tion. The writers will be glad to have 
the cooperation of other investigators 
in this field. 
LITERATURE CITED 
(1) Chamberlin, T. C., and Salisbury, R. O. 
1885. PRELIMINARY PAPER ON THE DRIFTLESS 
AREA OF THE UPPER MISSISSIPPI VALLEY. 
U. S. Geol. Surv. Ann. Rpt. (1884-85) 
6: 199-322. 
(2) Hall, E. C., and others. 
1921. SOIL SURVEY OF RINGGOLD COUNTY,. 
iowa. U. S. Dept. Agr. Bur. Soils, Field 
Oper. 1916, Rpt. 18: 1905-1929, illus. 
(3) Hawker, H. W., and Johnson, H. W. 
1919. SOIL SURVEY OF MUSCATINE COUNTY, 
iowa. U. S. Dept. Agr. Bur. Soils, Field 
Oper. 1914, Rpt. 16: 1825-1884, illus. 
(4) Knight, N. 
1902. ANALYSIS OF THE MOUNT VERNON LOESS. 
Amer. Geol. 29: 189. 
(5) McCourt, W. A., Albertson, M., and 
Benne, J. W. 
1917. THE GEOLOGY OF JACKSON COUNTY. 
Mo. Bur. Geol. and Mines. [Rpts.] 
(ser. 2) v. 14, 158 p., illus. 
(6) Marshall, P. 
1903. dust storms in new Zealand. Nature 
68: 223. 
(7) Palmeri, P. 
1901. SUL PULVISCOLI TELLURICl E COSMICI 
E LE SABBIE AFFRICANE. ANALISI E CONSID- 
erazioni. Rend. Accad. Sci. Fis. e Mat. 
[Naples] (ser. 3, v. 7) 40: 154-173. 
(8) Scovell, J. T. 
1897. GEOLOGY OF VIGO COUNTY, INDIANA. 
Ind. Dept. Geol. and Nat. Resources Ann. 
Rpt. (1896) 21: 507-576. 
(9) Shaw, W. N. 
1911. FORECASTING WEATHER, 1911. 380 p„ 
New York. 
(10) Thorpe, T. E. 
1903. “red rain” and the dust storm of 
feruary 22 . Nature 68: 53-54, 222-223. 
(11) WlNCHELL, A. N., AND MlLLER, E. R. 
1918. THE DUSTFALL OF MARCH 9, 1918. Amer. 
Jour. Sci. (ser. 4, v. 46) 196: 599-609. 
( 12 ) - 
1922. THE GREAT DUSTFALL OF MARCH 19, 1920. 
Amer. Jour. Sci. (ser. 5, v. 3) 203: 349-364, 
illus. 
