30 NEW YORK STATE MUSEUM 



accumulations it was discovered that by the dumping and filUng 

 process already described a great till barrier had been formed across 

 the Schoharie valley just south of the small village of Burtonsville. 

 That till barrier raised the waters of the Schoharie above that point 

 to a higlit of about loo feet greater than at present. The till has 

 been cut away down leaving cliffs largely of till but also in part, on 

 the concave side of the bend, cliffs of bed rock. It would appear 

 that this raising of the waters must have extended about 20 miles 

 up the Schoharie from Esperance and that the lake was maintained 

 there in the immediate postglacial times until the barrier could be 

 cut away. There is apparently a well marked delta belonging to 

 this lake above Centra] Bridge and along the valley towards Coble- 

 skill. The conditions of this lake- above Schoharie village need 

 further study for their full elucidation. 



Areas of marsh and Gbstructed drainage. It was not practicable 

 to distinguish in the mapping between areas of existing marsh and 

 areas of soft meadow which represent recent or comparatively 

 recent lake filling. These areas, however, serve in an interesting 

 way to show the obstruction of drainage caused by glacial deposits 

 and a moment's inspection of the map would show that where the 

 deposits are conspicuously massive, as along the belt of interlobate 

 moraine, the areas of marsh and lake fillings are conspicuous. 

 It is quite possible that many small areas apparently due to recent 

 lake filling, may have been areas also occupied by small lakes of 

 glacial age. This, however, can not be determined unless there 

 are chances for suitable excavation or exposure of the materials. 

 Thus along Auries creek about 2 miles southwest of Glen is a flat 

 ground about a mile in length which would naturally be taken as 

 a combination of lake filling and flood plain but a chance section 

 made by the stream shows massive lacustrine clays containing 

 glaciated stones and therefore demonstrably representing a lake of 

 glacial age. 



Sinnmary. The field investigations for these four quadrangles, 

 Broadalbin, Gloversville, Amsterdam and Fonda, are practically 

 completed and seem to show conclusively the presence of the two 

 great glacial lobes already described with a massive interlobate 

 moraine with scant evidences of any recessional moraine in the case 

 of the Mohawk glacier, but at least one conspicuous belt of reces- 

 sional moraine in the case of the Sacandaga glacier. The retreat of 

 the ice is marked by the presence of glacial waters, notably small 

 high level sand plains of the Sacandaga delta, the high level lacus- 



