EXPLANATION OF PLATE 28 



This plate is a north-south profile, in which the vertical lines 

 represent the latitude lines, 15 minutes apart, which form the 

 north and south boundaries of the quadrangles or sheets of the 

 state topographic map. The horizontal and inclined lines repre- 

 sent existing and ancient water levels with their angle of tilt in 

 the double scale of the section. One inch vertical equals 533 

 feet; one inch horizontal equals about 13.3 miles. The legend 

 attached to the sections explains special symbols. The several 

 lines, A-B, etc., indicate the following: 



A-B The solid part of the line connects the highest beach found 

 at Port Kent (Plattsburg quadrangle) with the highest 

 beach at Street Koad (Ticonderoga sheet) and represents 

 the present tilted attitude of this old water level be- 

 tween the two localities. The dotted extensions of the 

 line north and south meet certain beaches on the north 

 and come near the level of the deltas made in front of 

 the retreating ice sheet in the Highlands and south- 

 ward; it is a line of comparison. So far as present 

 evidence goes the waters of glacial Lake Albany and 

 Lake Vermont did not rise above the line. The de- 

 posits found above the line appear to have been made 

 in local bodies of water marginal to the ice sheet or to 

 have been deposited by glacial streams confined on rock 

 terraces similarly to those at West Point. Further in- 

 vestigation may show that some of the shore line traces 

 along this line on the north and certain deltas in the 

 middle Hudson valley were made at different times in 

 different water bodies. 



C D Lake Vermont, with beaches and deltas, at the time of 

 discharge through the Coveville channel or spillway 

 below Schuylerville. It will be noted that this water 

 level crosses the line A-B at the southern border of the 

 Plattsburg quadrangle near Port Kent. If A-B really 

 coincides with the earlier water level of the Champlain 

 valley, it follows that the land was tilted down toward 



