BEARING OF THESE STUDIES 99 



About 900 years after the readvance at Amherst, or during 

 years 5671-5676, there occurred a great drainage into glacial 

 Lake Albany. Figure 18 and curve 14 (PI. Ill) show it at Catskill, 

 65 miles below the then mouth of the Mohawk at Schenectady. 

 It is registered at other localities up to Albany, but the zone is 

 disturbed. It is the only drainage of importance into Lake 

 Albany for more than 600 years during the ice retreat in the 

 central and upper Hudson region. It records the sudden escape 

 of a large quantity of water, which must have rushed across an 

 abundance of easily eroded material. At the time of the drainage 

 the ice edge stood somewhat south of Cohoes; and west of the 

 Hudson, in all probability, it trended slightly north of west. 

 The ice border may accordingly have left the highland south 

 of the Mohawk River and the varves may record the drainage 

 of a lake through the Mohawk Valley after the small waters, 

 dammed in this valley, had escaped. These seem to have been 

 too small and to have drained out through channels too short to 

 allow them to pick up much material (see Fairchild, 1912). 

 The glacial lake in the Finger Lakes district discharged into the 

 Mohawk waters and accordingly indirectly into Lake Albany 

 (Fairchild, 1909, PI. 37; 1912, PI. 15). So it seems most likely 

 that the drainage varves mark the first escape of the vast waters 

 of the Great Lakes region which occurred during the stage known 

 as Lake Wayne, the successor of Lake Whittlesey (Taylor, 1913, 

 p. 306; 191 5, p. 386). This supposition is strongly supported by 

 the fact that the varves above the drainage layer are much 

 thicker than those beneath , the first twenty being two and a half 

 times as thick. This shows that the new tributary to Lake Albany 

 brought more material than was supplied by the glacial rivers 

 discharging into the lake and by all other tributaries together. 



Subsequent to this time of ice retreat the ice front readvanced 

 and closed the outlet at Syracuse (Taylor, 1915, pp. 392 and 398). 

 The resulting stage in the Great Lakes region, Lake Warren, 

 reached from the Finger Lakes district to the Huron basin and 

 discharged westward. The eastern barrier of the lake is probably 

 marked by the Niagara Falls moraine. This marked readvance 



