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NEW YORK STATE MUSEUM 



The slates present many lithologic variations and many inter- 

 esting stratigraphic and structural relations which can not be 

 given here. 



Metamorphism. In this report the general fact of greater 

 metamorphism of the Paleozoics to the east should be noted. 

 Reconnaissance in Dutchess county reveals that the metamorphism 

 of these rocks is a function of the distance of these strata from the 

 Hudson river in the northern portion of the county. At the south 

 apparently the increment by which metamorphism approaches a 

 given degree is greater per unit distance, and apparently is in 

 some way related to the proximity of the Highlands mass. 



The map and complete presentation of details and conclusions 

 are reserved for a later and fuller report on the geology of the 

 Poughkeepsie quadrangle. 



Surficial geology 



The examination of the glacial and postglacial deposits and their 

 interpretation in terms of the agents performing the work has 

 been continued during the past season by Prof. H. L. Fairchild in 

 the region about the east end of Lake Ontario, especially in the 

 area covered by the Grindstone, Alexandria Bay, Cape Vincent, 

 Clayton and Theresa quadrangles. The glacial and glaciolacustrine 

 features are striking and peculiar ; over all the area the deposits 

 were laid down under the deep waters of Lake Iroquois and the 

 north and east portions of the area were also covered by the marine 

 waters of Gilbert gulf. In the lowering of these waters all the land 

 surfaces were wave swept and in consequence the drift is mostly 

 gathered into the depressions. The two striking drift features are 

 the extensive clay plains which occupy the valleys and the lower 

 tracts and the few boulder moraines. The drift sheet as a whole 

 is scanty and many extensive tracts are essentially bare rock. The 

 striking physiographic features are the hummocks or rock knobs 

 in the districts of crystalline rocks, the broad plains produced by 

 the sedimentaries and the clay plains of the lowlands and valleys. 



Suggestions are found of a Prewisconsin glaciation, though no 

 interglacial or warm climate deposits are yet determined. Over 

 large tracts of the limestone the surface has been worn into broad 

 furrows and ridges, a huge " washboard " structure which has lost 

 its original glacial polish and striae. A later ice abrasion has cut 

 these parallel ridges usually at a considerable angle. The old 

 planation surfaces have lost much of their glacial character. In 



