Sqvtier■—Peculiar Deposits on the Mississippi Bluffs. 263 
to observation, the facts regarding them are more completely 
-available than are those connected with any other class of phe¬ 
nomena. 
The deposits in question may be concisely described by say¬ 
ing that they consist almost exclusively of material derived 
from the limestone capping of the higher bluffs (Lower Mag¬ 
nesian) occurring in positions to which no agency now oper¬ 
ative could have carried it under existing topographic condi¬ 
tions. 1 
Thus far, only two hypotheses have been suggested in ex¬ 
planation. 
1. That the deposits were formed as normal talus or hillside 
debris at a time when the topography was such as to permit it. 
That, in fact, they measure the topographic changes which have 
taken place since their deposition. 
2. That they resulted from the operation of some agent not 
now acting. Virtually this limits us to some from among that 
class of activities which we recognize as glacial. 
In describing the features as glacial phenomena one would 
wish to place them by the side of all other phenomena refer¬ 
able to the same cause. This, however, is not my present pur¬ 
pose, and I shall only speak incidentally of the glacial aspect 
giving my attention rather to such facts as bear on the first 
hypothesis. 
Geographically the occurrences which I have thus far dis¬ 
covered are all quite near the Mississippi River to which vi¬ 
cinity my search has been largely limited. Taking into ac¬ 
count only those which are well defined I may enumerate 
twelve of which eight are among the Trempealeau bluffs, which 
have been quite thoroughly explored, and four elsewhere, which 
include but an infinitesimal part of the possible localities. 
Classified according to the topographic features with which 
they are associated, six are on the bounding buttresses of circs. 
1 The typical deposits among the Trempealeau Bluffs have been 
viewed at different times by Messrs. Salisbury, Leverett and Weidman. 
Not one of them so far as I am aware, has committed himself to any 
explanatory hypothesis, but 1 think all would recognize the correctness 
of this definitive statment. 
