228 LIFE OF THE PLEISTOCENE 



The peat moss has been identified as follows: 10 



Hypnum (Harpedium) fluitans L. 



" " revohens Swartz 



" {Calliergon) richardsoni Lesq. and James 



The wood in the overlying Kansan drift 'which is to be correlated with the 

 Aftonian because it was incorporated in that sheet from the underlying soil 

 horizon) is identified as Larix americana. Of the mosses, revohens occurs in 

 deep swamps from northern Ohio to Alaska; richardsoni has been reported 

 only from British America and the coast of Greenland. It is thot by Savage, 

 therefore, that the climate in which these plants lived was of a more boreal 

 character than today. This is thot to be indicated, also, by the presence of 

 coniferous trees and the apparent absence of deciduous trees. It is probable 

 that the fauna reported by Calvin and Shimek represents the warm-temperate 

 climate and the Oelwein deposit the subarctic or cold-temperate climate, as 

 suggested by Chamberlin. 



Another exposure in Dodge Township, Union County, in the bank of a 

 small stream, tributary to the Grand River, gave the following section: 11 



4. Fine-grained, pebbleless soil, dark gray in color at the surface, changing to yellow 



in deeper portions 2 feet 



3. Yellow colored drift bearing numerous pebbles and small boulders, 'maximum 



thickness 21 feet 



2. Bed made up of alternating layers of brown colored vegetable matter and fine 



grained light gray sand. Greatest exposed thickness 6V2 feet 



1. Blue colored boulder clay containing numerous pebbles and small boulders of 



granite, greenstones, quartz and quartaite 10 feet 



No. 2 is referable to the Aftonian. At the base of the stratum is a layer 

 of clean, fine-grained sand, light colored, about 4 inches thick. Above this a 

 layer of vegetable matter % inches thick, crowded with branches and frag- 

 ments of wood. In the upper vegetable layers are leaves, stems and rhizoids 

 of mosses. The rootstocks of ferns, blades of grass-like leaves, fragments of 

 leaves resembling Populus and leaves and twigs of cone-bearing trees (Picea?) 

 were also found as well as the wing covers (elytra) of beetles. The moss has 

 been identified as 



Hypnum nitens (Schreb.) Schimp. 

 " fluitans L. 



It is thot that this region was first a land surface, then a shallow pond, 

 during which time the moss (which is aquatic) developed; this was drained 

 or filled up and again became a land surface. This was finally covered by the 



10 Macbride, Proc. Iowa Acad. Sci., IV, pp. 63-66, 1897, Savage, op. cit., XI, p. 108, 1904: 

 Holzinger and Best, The Bryologist, Nov. 1903. 



11 Savage, op. cit., p. 105. 



