ANCIENT WATER LEVELS OF CIIAMPLAIN-HUDSON VALLEYS 145 



second lower terrace at the base of Palmertown mountain [see 

 pi. 13]. The low escarpment which separates this lower delta 

 plain from the broad 400 foot terrace is a striking cliff of gravels 

 sweeping southward from the Glens Falls quadrangle to the 

 Schuylerville quadrangle on the south. As will be shown later 

 its base corresponds closely with the presumed level of a stage 

 of the glacial lake which covered this district and wave action is 

 to be suspected as determining the form of the terrace though 

 an earlier ice contact slope may have given rise to its position. 

 The topography bears every mark of having been produced by 

 erosion. 



The delta of this stage evidently extended as far east as Sandy 

 Hill and perhaps much farther toward Fort Edward. The 

 southern and eastern margin of the present delta plain have 

 been determined by erosion accomplished during the lower and 

 later stages of the waters in which the delta was deposited. 



The Hudson in its eastward course from the portal of the 

 Adirondack canyon lies mainly on the north side of the delta as 

 does the Mohawk in relation to the delta extending from Schenec- 

 tady to Albany. There is a narrow strip of delta sand west of 

 Glens Falls but within a mile north of the town and the bank of 

 the river there is little or no evidence of stream-borne waste. 

 Had the stream at any time wandered into this marginal field of 

 its delta before sinking its present channel the river would easily 

 have fallen into the course of Half Way creek and so joined the 

 Champlain drainage. It is to be .suspected that, where streams 

 flow along the northern margin of old deltas built into glacial 

 lakes of meridianal valleys, their courses were determined by 

 the natural tendency to diversion into the depression which 

 would arise on that side of a delta through the retreat of an ice 

 barrier. Xo satisfactory evidence of the presence of the ice on 

 the north side of the Glens Falls delta at this stage has been 

 observed. In fact the continued development of the deposit since 

 it might outlast the presence of the ice, did such a condition exist 

 at the commencement of the process, would tend to obliterate those 

 evidences of the ice contact on which the proof of the existence 

 of pteglacial deltas must over depend. Other postglacial changes 



