THE LANSING DEPOSIT NOT LOESS. 351 



portion of the ridge rises at least 180 feet above its northern 

 base, and an abundance of such material lies above the bottom 

 of the cave. 



Two species of land molluscs are common in the talus> 

 namely Polygyra albolabris and Pyramidula alto nata. Both 

 were also found living on the higher slopes of both ridges, a 

 and b ) PI. VIII, and their shells could have been mingled with 

 the slipping material. Recent specimens of these species, and 

 of Polygyra prof undo, and P. leai, were found at an altitude of 

 over 100 feet above the cave. 



The position of the deposit in which the human remains 

 were found is, therefore, such that the source of all the material 

 can be traced to higher points south of the Concannon house. 

 Much has been written concerning the thin, laminated band 

 which appears only on the west side of the cave, and Dr. 

 Chamberlin* regards it as probable that it was deposited by 

 the Missouri river when it occupied a higher level, about sixty 

 feet above its present bed. Professor Calvinf thinks the in- 

 creased altitude was "less than fifteen or twenty-five feet," 

 through which the Missouri may have cut since the formation 

 of the band, which would probably be approximately since the 

 deposition of the skeleton. Both of these writers were evi- 

 dently anxious to allow all the benefit of doubt on the side of 

 the greatest possible age of the deposit. Dr. Salisbury ex- 

 presses! the opinion that the water-laid layer was formed" when 

 high water in the Missouri ponded the tributary." This might 

 be possible, as the floor of the cave at the entrance is less than 

 four feet above the Missouri river high- water mark in 1903, 

 but it seems to the writer that the presence of this band can 

 be accounted for without reference to the Missouri river. The 

 .all north of the cave, marked b on PI. VIII, is higher and 

 more abrupt than the ridge a, in which the cave is excavated. 

 There has, however, been more or less washing and slipping 



*Pp. 774, etc., 1. c. 



tin comments on Dr. Chamberlin's paper, 1. c. , p. 778. 



tin comments on the same paper, 1. c. , p. 778. 



