PLEISTOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 461 



Gilbert's ' review (pp. 303-305) of the total fauna of the Bonneville and 

 Lahontan basins led him to the conclusion that the life throws little light 

 on the question of climate; in other words, it is inconclusive. He pointed 

 out that the testimony of the freshwater molluscs, which are similar in the 

 Bonneville, Lahontan, and Christmas Lake basins, so far as it goes, points 

 to the conclusion that the lacustral epochs were epochs of relative cold, 

 and favors the correlation of the high-water periods with the periods of 

 largest glaciers. 



(2.) Late Phases of the Equus Zone 



These late phases of the Equus Zone are apparently distinguished by the 

 absence of true camels and the presence of bison. At several points there 

 is evidence of the existence of man in the presence of palaeolithic spear or 

 arrowheads. 



The fauna is imperfectly known, and the above distinction between 

 'early' and 'late' is rather arbitrary at present. 



Early and late Pleistocene life of Kansas. — The geologic age of the 

 widely scattered Pleistocene deposits of Kansas still awaits determination 

 through the careful examination and comparison of the species. Williston, 

 Haworth, Hay, and Darton agree in a broad way on the following geologic 

 succession : 



Plains marl = loess = Pleistocene. 



Mortar beds = Ogallala Formation = Pliocene + Upper Miocene. 



The uppermost Miocene and Pliocene is dominantly sandy, gravelly, 

 and clayey, the consolidation into the so-called 'mortar beds' being due 

 to the penetration of water and presenting no test of geologic age. The 

 plains loess, or 'marl' (Hay) is a very irregular mantle; in places it is still 

 in process of formation as an seolian accumulation over sodded surfaces. 

 Near the base Matthew has collected well-petrified bones of Equus; near 

 the top one finds unfossilized bones of the recent bison. Some of the 

 principal localities are as follows: 



Twelve-mile Creek near Russell Springs, Logan County, Kansas 



(Fig. 194, 20). 

 'Sternberg's Elephant Bed,' Logan County, Kansas (Fig. 194, 20). 

 GooDLAND, Sherman County, Kansas (Fig. 194, 20, approximately). 

 Harper Township, McPherson County, Kansas (Fig. 194, 19). 



McPherson County, Kansas.^ — The watershed between the Kansas and 

 Arkansas river systems crosses at right angles a shallow trough about ten 

 miles wide in McPherson County. This trough contains sediments con- 

 sisting of: 



' Gilbert, G. K., Lake Bonneville. Monogr. U.S. Geol. Surv., Vol. I. Washington, 1890. 

 2 Lindahl, J., Description of a Skull of Megalonyx leidyi, n. sp. Trans. Amer. Philos. Soc, 

 n.s., Vol. XVII, Jan. 2, 1S91, pp. I-IO. 



