THE LOESS AND THE I.ANSING MAN. 2)2)1 



sheet thins out, as for example in most of the exposures north 

 of Decorah. It is also common along the Missouri. 



The fourth assumption, that loess is of the Iowan age, has 

 a certain amount of foundation in fact, but is unwarranted in 

 the extent of its attempted application. It is based on the in- 

 vestigations and reports of the geologists of the Iowa Geolog- 

 ical Survey,* who investigated the loess in some of the coun- 

 ties along the border of the Iowan drift. All the Iowa refer- 

 ences cited have special reference to this restricted area, and 

 in most cases the authors specifically so state. Bain (1. c, p. 

 461) says: "The loess found in the region has been referred to 

 the Iowan since it is believed to be in this region the equiva- 

 lent of the Iowan drift farther north, and now in part buried 

 under the Wisconsin. It is believed that loess of widely dif- 

 ferent ages occurs in the Mississippi valley." Calvin (1. c, p. 

 118) says: "Loess, or a product resembling loess, was developed 

 in connection with more than one drift sheet, and it is possible 

 that the Iowan loess blends into loess-like deposits of different 

 age in some portions of the extra-marginal territory." 



There is at present no warrant whatever for the reference 

 of all loess, and especially that of the Missouri river, to the 

 Iowan age, and even if it be possible to show that the Lansing 

 skeletons rested in undisturbed loess, this will not prove that 

 they belong to the Iowan. 



A thin layer of loess is found over a part of the Iowan and 

 the Wisconsin! and no connection has yet been established 



* Calvin, S. , la. Geol. Sur. , vol. vii. p. 89, 1897; vol. viii, pp. 173-4, 

 216, 18 ( )S; Bull. Geol. Soc. of Am., vol. x, p. 118, 1899. Bain, H. 

 Foster, la. Geol. Sur., vol. v, pp. 155-6, 1896; vol. vi, pp. 461-3, 1897. 

 Beyer, S. W. , la. Geol. Sur., vol. vii. p. 236, 1897; vol. x. p. 281, 

 1900. Eeverett, Frank, of the U. S. Geol. Survey, also tentatively re- 

 fers a part of the loess of Illinois to the Iowan. See U. S. Geol. Sur., 

 vol. xxxviii, p. 153, 1899. 



tShimek, B. , Proc. la. Acad. Sci., vol. iv. pp. 68-72, 1898. Bain, 

 H. F., la. Geol. Sur., vol. ix, p. 91, 18 c >9. Calvin, S. , Bull. Geol. 

 Soc. of Am., vol. x. p. 119, 1899: Iowa Geol. Sur., vol. xiii, pp. 328-9, 

 1903. 



