FOURTH REPORT OF THE DIRECTOR I907 29 



northeastward from Fort Hunter and they are found conspicuously 

 developed as appears by the map, from Hoffmans Ferry toward 

 Schenectady. Doubtless these deposits were much more extensive 

 than they are at present, having been largely swept away by the 

 waters of the river after Lake Albany subsided. Reference has 

 been made to the heavy tills of the Mohawk valley. These are 

 basal and massive on both sides of the river. At certain points as 

 already described, they are capped by the lacustrine silts and sands 

 of the higher level, but in many cases these sands, which must have 

 sloped down to the flood plain level originally, and amassed tills, 

 have been swept away along the lower slopes so that in cross-section 

 we should have massive tills sloping from the upland down to the 

 river. At certain points, as east of Fultonville and along all the 

 lower parts of the city of Amsterdam, are belts of water-swept till. 

 Along these lower grounds of the city of Amsterdam till is very 

 thin, bed rock near at hand, and east of the city are fields 

 of boulders which apparently are remnants of tills of which 

 great Iroquois currents have removed finer materials. For many 

 miles along the Mohawk river the deposits of the drift are exceed- 

 ingly steep. They are almost cliffs and there is an entire absence of 

 morainic contours. These forms could not have been constructional 

 in the glacial sense. When these tills were dumped into the AIo- 

 hawk valley they must have been purely morainic forms resulting 

 from a melting down of the ice tongues which occupied the viilley. 

 It would seem that these slopes of till with their occasional covers 

 of the customary silts have been powerfully undercut by Iroquois 

 waters, giving the steep slopes of the present, but it must also be 

 recognized that that tuidercutting could not effectively take place 

 until there was some subsidence of Lake Albany waters allowing 

 effective current action by the grade stream carrying the drainage 

 of the glacial Great Lakes. These facts and suppositions involve a 

 problem concerning the Iroquois drainage and the waters of Lake 

 Albany which deserves further and more final investigation. An 

 interesting remnant of the Lake Albany silts is found near South 

 Schenectady along the waters of the Normans kill. Here, near the 

 region of the Amsterdam quadrangle is a small embayment of Lake 

 Albany waters and therefore a reentrant area of sands which joined 

 with the greater area that appears in the Schenectady quadrangle. 

 Schoharie lake. An interesting development of lacustrine sands 

 and clays is found along the Schoharie river from Espcrance up 

 stream for some miles. In looking for a cause of these lacustrine 



