LOESS-DEPOSITING WINDS IN LOUISIANA 537 
1. The greater thickness and width of the eastern loess belt have 
been noted by many observers and usually explained as due to 
stronger and perhaps more persistent westerly depositing winds. 
From a rough calculation based on field notes the writer estimates 
that the loess in Louisiana below the Mississippi state line includes 
about 4 cubic miles, while the corresponding portions of the western 
belt includes only .8 of a cubic mile, or, roughly estimating, there 
is about five times as much loess in the lower eastern belt as in the 
corresponding portions of the lower western belt. These contrasts 
point to the greater work of westerly as compared with easterly 
winds. 
2. The same conclusion seems to be indicated by the composi- 
tion of loessial soils in the two belts. While the analyses are of 
soils and subsoils only, it is believed that the range of their com- 
positions corresponds to that of the underlying loess, since the soils 
have been subjected to practically the same weathering processes 
over both belts. Taking the composite soil analyses of the eastern 
~ loess belt below the Mississippi state line and the corresponding 
portions of the western belt, we have the following data? 
Number of Potash Phosphoric Acid 
Analyses (Lbs. me es (Lbs. per Acre) | (Lbs. per Acre) 
asternbelitvmmy sa. 21 5,540 8,500 980 
WieStennubelita nen ene 14 6,000 8,920 1,800 
The lime and potash are slightly higher in the western belt, and 
the phosphoric acid decidedly so. So far as can be determined by 
a microscopic examination, the lime and potash occur in feldspars 
with diameters mostly ;{/) mm. in diameter or less. Most of the 
phosphoric acid occurs in the very fine particles, the fine silts and 
clays, with diameters below 7; mm. These fine particles are 
difficult to study microscopically, and the writer has been unable 
to identify the phosphate-carrying minerals except for an occasional 
particle of apatite. However, the point to be emphasized in this 
connection is that the particles carrying lime, potash, and phos- 
phoric acid are very small, and it is believed that the higher 
t Analyses by I. Selecter, Soil Chemist, Louisiana State Agricultural Experiment 
Station. 
