64 XEW YORK STATE MUSEUM 



its remnants can be gained because it was only imperfectly devel- 

 oped there. 



It is quite certain that much of the faulting, including the Indian 

 lake fault, which has so largely influenced the major topographic 

 features of the southeastern half of the Adirondacks took place 

 after the development of the Cietaceous peneplain and probably 

 at the time of its uplift. Other zones of fracture, however, like 

 the Long Lake fault, whose displacements show little if any in the 

 existing topography, are probably much older, and they may in part 

 at least be of even Precambrian age. 



Cenozoic History 



The existing relief features of the Blue ^lountain quadrangle 

 have been produced chiefly by the dissection of the upraised Cre- 

 taceous peneplain. As a result of the uplift the streams were 

 greatly revived as erosive agents and they proceeded to carve out 

 channels and valleys principally along the comparatively weak 

 Grenville belts and the fault zones of weakness. 



Late in the Cenozoic era the area of the quadrangle, in common 

 with most of the State, was deeply buried under the great ice 

 sheet of the glacial epoch. ]Many local details of topography, especi- 

 ally in the valleys, are due to accumulation of glacial deposits. 



ECONOMIC PRODUCTS 

 As compared with many portions of New York State, the Blue 

 Mountain quadrangle is notably deficient in geologic deposits of 

 value under present-day commercial conditions. The lack of cheap 

 transportation facilities prevents the working of certain deposits 

 which might otherwise have some value. Building stones, so- 

 called " road metal," sands and gravels for local use are the only 

 materials now taken out. No ore deposit of any kind which may 

 ever be successfully mined was observed by the writer. All the 

 stone quarries and prospect holes of the quadrangle are indicated on 

 the accompanying geologic map. 



Building Stones 

 Fresh rock from any of the facies of the large masses of syenite 

 or granite would yield btiilding stones of great strength, resistance 

 to weather and adaptability to high polish, but no large quarry exists 

 in the region. Some typical greenish gray, quartzose syenite has 

 been taken out for local use from the quarry one-half of a mile 



