ON THE PROBOSCIDEAN FOSSILS OF THE PLEISTOCEME DEPOSITS. 53 



from the loess. There are at least eight of these. Six or seven 

 came from the base of the loess, and nearly all of these were from 

 the area covered by the lllinoiau drift. One, or perhaps two, came 

 from Fremont connty, in Iowa, and hence were from the area of 

 the Kansan drift. All of these might perhaps as well be classified 

 with the fossils in the ferretto zone and \Aith those in the loess- 

 covered upper surface of the Illinoian drift, for they were evidently 

 buried at the beginning of the accumulation of the loess in which 

 they lie. If the modern view that the loess is a land deposit is 

 correct, it appears quite ])robable that its basal part is not every- 

 where of the same age. The loess may have begun to form on the 

 Kansan drift even before the Illinoian ice invaded this region. On 

 the other hand, the relation of the loess to the lowan drift is such 

 as to make it unlikely that the bulk of the former deposit is of a 

 later date than this drift itself. Therefore we are justified in be- 

 lieving that the fossils which come from the base of the loess are 

 post-Kansan and pre-Iowan, when found beyond the limits of the 

 Illinoian drift, and when they come from the area of this /till, 

 they must be post-Illmoian and pre-Iowan. 



From Grinnell, in Iowa, a mastodon is reported as coming 

 from the loess. Grinnell lies on the area of the lowan drift, and 

 while this drift usually is without any loess covering, such a cov- 

 ering is reported as being present in the adjoining (Tama) county. 

 This loess is, of course, of post-Iowan age, and so must this fossil 

 be, which was excavated from a depth of six feet from the surface. 

 Two mastodon teeth are also reported from a creek on the lowan 

 drift in Forreston township, in Ogle countj^, in Illinois,and the great- 

 er part of a skeleton of the mammoth was recovered from a boggy 

 place in Lynnville township, in the same county. This latter point 

 is almost on the boundary between the Wisconsin and the lowan 

 drift, and, it may be, on the surface of the latter. In either case, 

 the interment of this fossil was probably much later than the de- 

 position of the lowan drift, as it came from near the surface. The 

 same must be said of some other finds which have been made at 



