350 NATURAL HISTORY BULLETIN. 



posits evidently erroneously included in loess by McGee is 

 given in the following paper. The objection to the inclusion 

 of the Lansing deposit in typical loess is that both its com- 

 position and position indicate that it was formed largely by 

 slumping or creeping from the adjacent highlands, and that 

 it is, therefore, a talus. If shells, or the bones of a mammal, 

 were buried in the sandy talus at the base of a Minnesota St. 

 Peter sandstone bluff, we would scarcely assign such remains 

 to the St. Peter formation. Similarly, even if the clay under 

 which the Lansing remains were found was originally loess, 

 if it has been disturbed, either by a slow creeping movement 

 or by a sudden land-slide, we cannot include any remains 

 overwhelmed in such movement with the original loess. If 

 only the possibility or probability of such movement can be 

 shown, it at least throws doubt upon the age of materials im- 

 bedded in such a deposit and makes the evidence of their age 

 extremely unsatisfactory. 



As already indicated the composition of the Lansing deposit 

 shows that it is not loess, and its position is such that the pro- 

 bability of creeping and slumping is at once apparent. 



The details of the location of the Concannon cave have been 

 quite fully set forth in the papers of Chamberlin and Winchell, 

 but the accompanying plat and views may be of assistance in 

 still further elucidating the environment of the deposit in which 

 the excavation was made, and showing its probable origin. 



The cave or tunnel, is situated at the base of a long ridge 

 which slopes downward toward the north.* 



The core of this ridge consists of carboniferous rocks,covered 

 in its upper part with more or less drift and loess, and at the 

 base with the talus in question. Carboniferous limestone here 

 crops out high above the talus in which the cave was excavated 

 and this, and the loess and drift above, appear to have fur- 

 nished the material which makes up the talus. The higher 



*See Plate viii, c for location of cave, and Plate ix, figs. 1 and 2 for 

 the ridge. 



