528 



HISTORICAL GEOLOGY. 



in an overthrust flexure, with the Hudson slates (d) lying in the syncline. 

 The fault extends for many miles to the north and south. 



Fault at Snake Mountain, Vt. — P, fault ; a, Trenton limestone ; b, Chazy limestone ; c, Cambrian ; d, Hud- 

 son shales. A. Wing. 



The great western fault of eastern New York, as described by Walcott, 

 enters New York from Vermont in Hampton, Washington County, and 

 extends south- southwest to the Rensselaer County boundary line, passing 

 through Argyle to Bald Mountain in Greenwich and beyond. In the fault, 

 as in those of Vermont, the Lower Cambrian strata are upthrust westward 

 over the Silurian. Fig. 732 represents a section of Bald Mountain, as viewed 

 from the south. According to it the plane of the fault dips at the low angle 



Section of Bald Mountain, the profile as seen from the south. Ch, Chazy limestone ; E, Calciferous ; X, S, 



shales. Walcott. 



of 25°. To the right are the Cambrian beds, and to the left, the underlying 

 Chazy and Calciferous, and in other localities the Trenton and Hudson for- 

 mations. Another similar fault, of like westward thrust, and on a nearly 

 parallel line, lies three to four miles farther eastward ; and a third, still more 

 to the eastward. The amount of displacement- at Bald Mountain is stated 

 to be between two and three miles. 



For a map of the Taconic limestone belts, as now existing in part of 

 eastern New York and the associated schists and quartzytes of western 

 Massachusetts and Connecticut, reference may be made to a description of 

 the region in the author's papers of 1880, 1881, and 1885, 1887. The chief 

 belts lie to the west of the Green Mountain Archaean protaxis, and continue 

 west of it into eastern New York, and also, after an interruption, in belts 

 that cross Hudson River into New Jersey and beyond. The largest belt is 

 that of Eolian limestone (or marble) of Vermont, and the Stockbridge lime- 

 stone of Berkshire, Mass. (so named by E. Hitchcock), lying to the eastward 

 of the main Taconic Ridge. It passes by the east side of Mount Washing- 



