GEOLOGY OF THE BLUE MOUNTAIN QUADRANGLE 55 



now occupied by Raquette lake is certain, there being only a drift 

 dam at the western end of Utowana lake. From the Raquette lake 

 basin the Preglacial drainage was either northeastward by way of 

 Raquette river as now, or southwestward by way of the valley now 

 occupied by the Fulton Chain lakes. Although this problem has 

 not been carefully studied in the field, the presumption favors the 

 southwesterly course. Thus, the interval of a mile between Brown's 

 Tract inlet and Eighth lake is wholly occupied by drift deposits, 

 while the valley occupied by the upper lakes of the Fulton Chain 

 has its bottom covered with drift which, because of irregular thick- 

 ness, at times acts as dams to pond the w^aters of the upper lakes. 

 A maximum thickness of less than lOO feet of drift just north of 

 Eighth lake is all that is necessary to account for the blockade of 

 the southwesterly Preglacial channel with resultant ponding of the 

 waters to form Raquette lake. Further evidence for this view lies 

 in the fact that between Forked lake and Long lake, Raquette river 

 descends more than lOO feet in about 3 miles mostly by a series 

 of cascades over rock ledges which extend across the narrow 

 channel. Apparently a Preglacial col was situated not far below the 

 outlet of Forked lake, the drift accumulation southwest of Raquette 

 lake being sufficient to pond the waters of the Raquette and Forked 

 lake basins to overflow this col (see figure i). 



Long lake basin. Granting the source of a Preglacial stream 

 on a col (near the outlet of Forked lake) a few miles above the 

 upper end of Long lake, did this stream follow the present course 

 of Raquette river into the St Lawrence? That the depression now 

 occupied by Long lake was a Preglacial stream channel is certain, 

 and also there is strong evidence that the drainage from this channel 

 passed eastward into the Hudson river rather than northward by 

 way of Raquette river. Regarding Raquette falls, on the river a 

 few miles below the outlet of Long lake, Cushing says : " There 

 is a fall of 70 to 80 feet in a gorge three-quarters of a mile long, 

 in which the water is rapid throughout, but w^th two principal falls. 

 There is an impassable rock barrier here, with no opportunity for a 

 buried channel, so that there could have been ,no Preglacial drainage 

 line ; rather, there was here a col between small streams flowing 

 both ways from the obstruction." ^ Thus, in Preglacial time, two 

 streams drained into the depression now occupied by Long lake, one 

 north-flowing from the col near the outlet of Forked lake (Raquette 

 lake quadrangle), and the other south-flowing from the col at 



1 N. Y. State Mus. Bui. 95, p. 444. 1905. 



