ANCIENT WATER LEVELS OF CHAMPLAIN-HUDSON VALLEYS 69 



The first of these segments, including the source of the river, 

 embraces the course of the Hudson within the Adirondack region, 

 which part, for convenience of description, will be called the 

 Adirondack-Hudson river. It is a region of the most ancient 

 rocks in the State and of the highest relief. With this stream, 

 this report is only incidentally concerned. 



The second segment includes the river from its point of emer- 

 gence from the southeastern base of the Adirondack mountains 

 to the northern portal of the Highlands in Dutchess and Ulster 

 counties. It is a lowland region of ancient Paleozoic strata. It 

 is divisible into two segments for convenience of treatment, an 

 Upper and Middle Hudson valley. In this report the Upper Hud- 

 son is meant to include the valley from the head of tide and the 



Fig-. 1. Early Cenozoic stage of the Hudson valley. The river is at or near base level; 

 it has widened out the rock bottom of its valley to form a narrow plain 2 toB miles wide. 

 The stream is probably meandering- and more or less alluvium sheets over the bed rock. 



recent delta of the river near Troy to the base of the Adirondack 

 mountains. The term Middle Hudson applies to the valley from 

 the head of tide to the northern edge of the Highlands. 



From the point of view of the Pleistocene deposits which the 

 Upper and Middle Hudson valleys exhibit the region may be 

 divided into (1) the Fort Edward district on the north, in which 

 the history has several features in common with the Cham- 

 plain valley on the north; (2) the large tract in which 

 both banks of the river are bordered by the newer brick clays from 

 immediately south of Fort Edward to probably the vicinity of 

 Rhinebeck ; (3) the Poughkeepsie district, in which the latest clays 

 are wanting, extending from somewhere north of Staatsburg and 

 the southern limits of the Albany clay district as far south as the 

 mouth of Wappinger creek and the northern part of Newburg, 

 where older clays begin to be heavily developed; (4) the Newburg 

 district, extending from the last southward to the Highlands. 



