GLACIAL WATERS IN BLACK AND MOHAWK VALLEYS II 



The map, plate 2, shows this frontal moraine which was built along 

 the ice margin, extending from Boonville southeast across the map. 



While the ice was building this moraine the high-level waters 

 which occupied a section of the Mohawk valley flooded the ground 

 in front of the ice. The heavy drainage from the mountains 

 brought down an enormous volume of detritus into the shallow 

 waters fronting the glacier and built the extensive sand plains in the 

 region of Forestport, having an altitude from 1440 feet down, and 

 which apparently entirely filled the lake in that district. These delta 

 deposits are described later (page 12). 



This lake was held between the Ontarian and Hudsonian ice lobes 

 and is believed to have outflowed through the Otisco and Unadilla 

 -valleys to Susquehanna drainage. It is described later in this paper 

 (see page 19). The waters fell by the ice recession opening lower 

 outlets in the Schenectady region, and the lowering was probably 

 going on while the ice front in the Forestport-Remsen district was 

 receding. At length the water surface fell below the divide or 

 water-parting which bounds the Black river hydrographic area and 

 the Black waters were differentiated as a distinct lake. 



SECOND stage: forestport lake; remsen outlet- 

 The first outflow of the distinctive Black waters was across the 

 moraine, forming the divide, north of Remsen, and then south 

 through the depression in which Remsen is located. The river 

 reached standing waters and built deltas four miles south of Rem- 

 sen, at Trenton and Trenton Falls. These features are shown in 

 plate 2. 



The Forestport lake with its overflow by Remsen must have per- 

 sisted until the ice front had receded southwestward halfway to 

 Rome, or to the west flanks of Quaker and South hills through a 

 distance of over 10 miles, so as to open the Lansing kill outlet. The 

 altitude of the lake surface was about 1240 feet during its closing 

 phase. The altitude at the inception of the lake was as much above 

 1240 as was the amount of downcutting of the Remsen outlet, which 

 vv^as no more than perhaps 20 or 40 feet. It could not have been as 

 much as 80 feet, as the next highest col, three miles northeast of 

 Remsen with map altitude 1320 feet, is uncut by stream flow. We 

 do not know where the early overflow and cutting occurred and we 

 have no check in delta heights in the lake area, as these lie at various 

 heights, this lake being merely the successor of the higher Mohawk 

 waters. 



The Forestport waters were shallow and the boundaries very 



