GEOLOGY OP ^HE VICINITY OP LITTLE PALLS 77 



weathered Utica shale before it was closely examined. To the 

 north, and overlying this, is a sloping sand terrace at from 1000 

 to 1040 feet, followed to the north by the heavy sand hills of the 

 tame moraine. The whole combination seems to indicate a local 

 obstruction of the drainage coming down from the north by the 

 ice lobe, as it was retreating south from the position of the 

 moraine, forming a small lake in which the clay was laid down, 

 on top of which the streams thrust out a delta. Further retreat 

 permitted the formation of the lower delta near Dolgeville. 



Still farther north, the " Pinnacle " kame sands are seen to lie 

 on a similar laminated clay, which there is at 1200 feet. In the 

 single exposure seen the dip is at first nearly, flat and then rapidly 

 changes to one of 45° to n. 50° w., suggesting a possible disturb- 

 ance by the ice, in which case the clay would antedate the last ice 

 advance. 



In the tributary to Crum creek at Manheim Center, at an eleva- 

 tion of 520 feet, is a laminated, fine clay with occasional minute 

 pebbles. It lies too high for association with the 440 foot water 

 level, and seemingly too far east to have any relationship with 

 ihe 600 foot level west of Little Falls. It shows no associated 

 sands, and appears to be overlain by morainic accumulations, in 

 which case it also must have been laid down prior to the last ad- 

 vance of the ice. 



But whether these different clays are older or younger than the 

 time of last ice advance, their great variation in altitude affords 

 a difficult matter for explanation, and seems to the writer to indi- 

 cate small water bodies produced by extremely local conditions. 



Drainage. Brigham has sketched an outline of the drainage de- 

 velopment of the district in preglacial times, with which the 

 writer is in full accord and to which he can add nothing. To this, 

 those interested are referred.^ 



Just before the onset of the ice, the drainage of the district con- 

 sisted of the main, east-west trunk valley, worn out along the 

 Ibelt of weak rocks under the Medina, into which came tributary 

 streams from the north and south, the whole constituting a well 

 developed drainage network which had carved prominent valleys. 



"Op. cit. p.184-92. 



