THE ILLINOIAN ICE INVASION 325 



6. Third glacial (Wisconsin) epoch. 



7. Post-Glacial time. 



Number 3 may be of Yarmouth age and number 5 of Sangamon age; or 

 these may be respectively of Sangamon and Peorian age. Number 5 might 

 also be an interval between older and later Wisconsin time. Tarr's section 

 from artesian well borings in Ithaca may include some of the strata mentioned 

 above (see page 149). 



Of Sangamon land surfaces there is but little evidence. In the Watkins 

 Glen-Catatonk Folio, 179 reference is made to an older drift in Watkins Glen, 

 underlying 100 feet of Wisconsin drift. In the blue clay underlying the drift 

 and overlying a bed of sand and gravel, the leaf of an Arctic willow (Salix 

 reticularis) was found. This deposit is thot to 'have been laid down during the 

 advance of the Wisconsin ice, and the willow adds additional weight, as it 

 represents a cold climate. 



The remains of a mastodon, together with vegetation, were found in pot 

 holes in the bed rock at Cohoes, Albany County, beneath the drift. These are 

 at least as old as the Sangamon, if indeed, they are not of greater age. Six 

 species of trees are represented. 18 " 



Pimts sirobus Larix americana { — laricina) 



Picea canadensis Acer rubrum 



" nigra ( = mariana) Betula alba 



A beaver dam with beaver cut sticks was also observed. 



Many years ago 181 a fox (Urocyon cinereoargentatus?) was reported from 

 Broome County "in fine clay beneath drift, in elevated ground which separated 

 the upper courses of the rivers Delaware and Susquehanna near the line which 

 divides New York and Pennsylvania. " The bones were found 40 feet below 

 the surface at a point 1375 feet above tide. The deposit appears referable 

 to the Sangamon interval. 



A tusk of a proboscidian, probably of Mammut americanum, was found 

 recently in a gravel pit in Pony Hollow, twelve miles southwest of Ithaca. 181 * 

 The deposit was stratified sand in a terrace "whose top follows the valley wall 

 above the outwash gravel plain which occupies the floor of the valley. The 

 exact origin of this Pleistocene terrace is obscure but it is certainly not later 

 than the end of the occupation of the valley and may be earlier. " It is possible 

 that this terrace may be post-Illinoian and the tusk of Sangamon age. 



179 U. S. G. S., Atlas No. 169, p. 26. 



1,0 Amer. Jouxn. Sci., (ii), XLIII, pp. 115-116, 1867. 



131 Redfield, Proc. Amer. Assoc. Ad. ScL, 2nd Meeting, 1850, pp. 255-256. 



ma Sheldon, Science, N. S., XLI, pp. 98-99. 



