ANCIENT WATER LEVELS OF CHAMPLAIN-HUDSON VALLEYS 115 



Chapter 3 



GLACIAL DEPOSITS OF THE MIDDLE HUDSON VALLEY 



North of the Highlands the glacial features of the Hudson take 

 on a somewhat different aspect from those seen on the south. 

 At Newburg and Fishkill glacial clays come to the river front in 

 the form of terraces capped by sand and gravel, but gradually 

 give way upstream to coarser and coarser stratffied deposits, 

 till at New Hamburg on the east bank glacial gravels appear like 

 those near Peekskill. Thence northward to near Kingston point 

 the glacial deposits bordering the river below the 200 foot contour 

 are mainly ill defined deposits of gravelly till or rude kames such 

 as are laid down wliere large masses of ice have melted out. The 

 molding sands of this district are perhaps of a different origin. 

 From Kingston northward to Alban^^ and Troy there comes in a 

 remarkable series of clay deposits which everywhere show by their 

 surface being free of later drift and by their sharp incision by 

 postglacial streams that they are distinctly later than the occu- 

 pation of the valley by the glacier or its remnants and that they 

 are, in fact, the most recent of the series of deposits which are to 

 be associated with the disappearance of the ice. It remains to 

 set forth what has been learned concerning the retreat of the ice 

 sheet from the Hudson valley between the Highlands and the 

 Mohawk north of Albany. 



Cornwall terrace. On the west bank of the Hudson at the 

 northern portal of the Highland canyon is the heavy deposit of 

 gravel which constitutes the Cornwall terrace. The materials are 

 very well shown in the cut bluff at the railroad station near the 

 river. The materials all show signs of strong water action but 

 not without the presence of ice. In the road up the hill from the 

 railroad station a boulder 6 feet long was exposed at the time of 

 my visit. The top of the terrace slopes toward the river and is 

 covered with coarse drift. It is difficult to arrive at any satis- 

 factory conclusion concerning the level of standing water at 

 this stage from the remnant of the terrace. The surface 

 as it exists may have been shaped above the level of the water 

 in the Hudson gorge. The altitude of 170 feet is attained by the 

 flat surface somewhat back from the brink of the bluff. On the 



