POSTGLACIAL FEATURES OF THE UPPER HUDSON VALLEY 1 5 



at 380 feet altitude and swept the plain at A^Ealta four corners at 

 390 feet. During the time of the Iromohawk flow the detritus 

 carried by the Maltaville distributary seems to have been carried 

 around the ice block and eastward to form the delta plains west of 

 Mechanic ville. If the basin had existed during the episode of the 

 river flow it would surely have been filled, as Stoller recognizes, but 

 in such case it would have been channeled as the standing waters 

 fell, and today we should find there a detrital plain with a channel 

 traversing it, similar to the Willow Glen gorge toward Mechanicville. 



The topography of the basin indicates that the ice block originally 

 occupied the space north and east of Maltaville and south as far as 

 Usher. The abrupt limits of the higher sand plains indicate a barrier 

 to their extension. The block of ice probably occupied all the rotund 

 area within the 300 feet contour, with dimensions about 3 miles north 

 and south and over 2 miles east and west. This is suggested on the 

 map by the area shaded in green. 



Distinct stream channels appear west of Round Lake village at 

 300 feet altitude, while lower cutting, in rock, shows in the eastern 

 edge of the village and close to the lake down to 200 feet. This 

 proves that the district had lifted out of the standing water to that 

 level. The total uplifting has been over 375 feet; hence 175 feet of 

 rise had occurred while the persistent but diminished ice block held 

 the flow to its southward course past what is now the west side of 

 the lake. The topography suggests that at this time the ice mass had 

 shrunk to about the limits of the 200 feet contour. 



A series of terraces north and east of the lake shows the effects 

 of the lowering waters lying against the waning ice, while the broad 

 plain south of the lake shows the eroding and leveling work of the 

 latest river flow. The ravine below East Line and the deeper 

 channel of the Anthony kill toward Mechanicville have been deepened 

 by the present creek. 



Some explanation of the cause for the long persistence of drift- 

 buried ice blocks may be found in another writing (17, pages 232-33). 



ORIGIN OF SARATOGA LAKE 



The basin of Saratoga lake, like that of Round lake, appears to be 

 an ice-block depression. The abrupt fronts of the delta sand plains 

 west and south of the lake suggest that they were banked against 

 an obstruction. It would seem that the heavy flow of the Drummond 

 distributary would in free course have spread the detritus into the 



