298 The American Geologist. November, 1902 
not similarly disintegrate, and are preserved as fossils, partly 
because of their composition and texture which better enable 
them to resist exposure, and partly because all of these 
terrestrial snails are more or less inclined to burrow, or at 
least conceal themselves in the lowest strata of leaf-mould) 
etc., and their shells are soon covered up.* In many respects 
the borders of the drift-sheets in the north, especially where 
morrainic, presented conditions similar to those now existing 
along the larger streams. This question, however, does' noi 
concern the loess of Natchez and A'icksburg, and will be dis- 
cussed at another time. 
Whatsoever ma}' be the difference of opinion concerning 
the soundness of the foregoing conclusions, the loess oi 
Natchez materially reinforces the evidence against the pos- 
sibility of the aqueous origin of the loess, and practically 
renders the theory of glacial origin untenable. 
The writer desires here to express his obligations to 
President Fish of the Illinois Central R. R. and Prof. Samuel 
Calvin of the Iowa Geological Survey, whose kindly courtesy 
made the preparation and publication of this paper possible. 
EXP LAN A TION OF FLA TES. 
PLATE X. 
A SMALL, "GULF" SOUTHEAST FROM EXPOSURE NO. 6. THE 
STRATIFIED ORANGE SANDS SHOW^ IN THE BLUFF. THE 
LOESS IS NOT VERY DISTINCT. THE BOTTOMS OF 
MOST OF THE BROADER GULFS ARE QUITE 
FLAT, AND CONTAIN NO PERMANENT 
STREAMS. 
PLATE XI. 
LOOKING SOUTHEAST FROM A POINT EAST OF EXPOSURE NO. 7. 
THE UPPER VERTICAL PORTION IS LOESS. BELOW IT IS 
AN IRREGULAR, RATHER NARROW LAYER OF DARK 
BROWN LOAM, AND BELOW THAT THE ORANGE 
SANDS AND GRAVELS ARE COVERED 
LARGELY BY A LOOSE TALUS. 
*To collect some of our smaller species of modern snails which are 
also represented in the loess, in autumn or during dry summers, it is 
necessary to pull up the roots of smaller plants among which many of the 
snails are concealed. 
