28 NEW YORK STATE MUSEUM 



direction of the land drainage of the valley wall). They were 

 made by stream-flow and ice-wear of probably more than one 

 earlier glacial epoch, and certainly were occupied by the lateral 

 drainage during the advance of the last ice as well as during its 

 recession. The glacial rivers which we are considering only fin- 

 ished a work partly done long before. 



The ice body in the Hudson valley lying over Albany and Sche- 

 nectady must have pressed against the Helderberg scarp for a long 

 period. The hypothetical relation of the ice lobe to the land con- 

 figuration is suggested in the maps, plates 14, 15. 



There are two passes across the divide, in Albany county, between 

 the Schoharie and Hudson valleys which are inferior in altitude 

 to the Cedarville outlet, but only the lower one was effective as a 

 river channel. The col at Knox, five miles southwest of Altamont, 

 at 1 160 feet, is uncut and no evidences of stream work are found 

 on the slopes of the valley. It appears that during the earlier and 

 higher outflow of the Schoharie waters along the face of the Helder- 

 berg scarp the Knox and Delanson passes were submerged in the 

 lake waters. Eventually the lake was lowered so that flow occurred 

 through the Delanson pass; and when the Schoharie waters' were 

 finally drained down to about 900 feet the Delanson river was 

 established. The present altitude of the channel, two miles west of 

 Delanson, is 840 feet. 



This channel is a good example of an abandoned stream bed, 

 though not nearly so capacious and mature as the Cedarville. The 

 outflow was reduced in volume because the ice was out of the 

 Mohawk basin and the supply of water from the melting glacier 

 was greatly diminished. The life of the river may not have been 

 long, as a still lower escape was to be opened northwest of Schenec- 

 tady. The earliest flow through the Delanson channel was forced 

 southeast through the valley of the Boxen kill and the site of Alta- 

 mont. 



The area of the Schoharie waters was probably the whole basin 

 of the Mohawk and its tributaries east of Utica and all of the 

 Sacandaga valley that was free of ice. The height of the water on 

 the Little Falls parallel began at about 1200 feet and fell to about 

 880 feet. On the parallel of Schoharie and Cobleskill the water- 

 planes will range from 11 50 down to 830 feet (see plate 14). 



No exhaustive study has been made of the planes and deltas of 

 this stage, but sand plains have been noted in far-separated locali- 

 ties, some of which are indicated in plates 2, 7 and 8. The follow- 

 ing delta plains are regarded as correlating with the Knox-Delanson 



