110 E. W. Hilgard—The Leess of the Mississippi Valley. 
of land- as compared with fresh-water shells, may be a question 
deserving investigation. That the phosphatic bones shoul 
always very much scattered, many bones belonging to the same 
individual being rarely found together, but seeming to have 
drifted widely apart. It is not easy to see how the cumbrous 
bones of the Mammoth could have been widely separated in a 
subaérial deposit. 
But I think that apart from its geological and other relations, 
there is intrinsic evidence in the nature of the material, contra- 
dictory of its xolian origin. In a paper lately published, I 
have drawn attention to a general distinctive feature of fine 
detrital aqueous deposits, viz: the necessary state of “floc- 
culation” in which they are deposited, so long as the water is 
not absolutely quiescent. Excepting only under conditions of 
such moisture as would preclude the possibility of conceiving 
the wind as an adequate cause, dust deposits cannot be in a 
flocculated condition, but in the very nature of the case must 
consist of single grains closely packed. It is true that this 
axiom does not seem to accord with our every-day experience; 
ly fixed by the calcareous incrustation, precisely as should b 
e case if it were an aqueous deposit; while if a wind-deposit 
we should expect it to be cemented bodily into a continuous, 
rock-like mass: I submit that this structural peculiarity ren- 
ders the aqueous origin of the loess extremely probable. It 
production of slaty cleavage by pressure impracticable; and on 
the other hand, I intend to ascertain by direct trial, in what 
manner the loess material will be deposited by an artific 
wind, after freeing it from the calcareous cement by digestion 
in weak acid ; and also, what will be the effect of pressure upo? 
the material so treated, in the tamped condition on the one 
hand, and in the floceulated on the other. 7 
