282 riic American Geologist. November, iwi 
the bluff had sHpped in part and thus exaggerated the apparent 
thickness of the loess. Such slipping was well illustrated oij- 
posite exposure Xo. 12 at .r. A mass of loess about 25 feet 
high. 15 feet wide and 165 feet long slipped vertically about 
two feet. Subsequent erosion of the face of the blufif at one 
end of the mass luade it appear as though the mass extended 
from the original upper surface to the new lower surface, — a 
distance of about 2/ feet. The underlying Orange sands, which 
are eanly washed out, always make such faults possilile, and 
conseciuently care must be exercised in making measurements 
on the exix)sed faces of blufTs. 
The material of the deposit possesses typical loess char- 
acters. It is a fine yellow or slightly bluish clay, showing a 
tendency toward vertical cleavage, containing lime nodule? and 
iron tubules, occuring on higher grounds, and abundantly fos- 
siliferous. Its hypsometric distribution is also like that of the 
northern loess, for it mantles the hills, and varies but little in 
depth. This is well illustrated in Plate XL In many respects 
it is strikingly like the loess along the ^Missouri river, being 
somewhat coarser and containing more lime, and consequently 
eroding less readily, than the loess of the upper Mississippi 
valley in Iowa and Illinois. But for the undermining of the 
underlving sands and gravels it would long resist the action of 
air and water. Along the X. O. & X. \\\ R. R., in the cut 
near the depot, (exposure i on the map), the very steep sides 
still retained the marks of pick and shovel at the time that the 
photograph reproduced in Plate XII was taken, though the 
excavation had been made about seven years before. 
This similiarity of the X'^atchez loess and that of the ]\Iis- 
souri river bluffs in all excepting fossils suggests the probable 
source of much, if not all. of the material which composes it. 
The fossils are the most interesting feature of the southern 
loess. Here, as elsewhere, the characteristic fauna is mol- 
luscan, but differs in many respects from that of the northern 
loess. Xotwithstanding the fact that the fossils formed the 
special object of the writer's investigations, there were found 
among them no species which are aquatic, or in any sense 
even "semi-aquatic." X'ot even those forms which belong to 
the fauna of the small pond and shallow stream, and which 
sometimes occur in northern loess, were found here. Singulai- 
