214 PALEOZOIC TIME. 



ington, in the southwestern corner of the State, is 2,634 feet above the sea. Graylock, 

 in the northwestern, 3,600 feet high, belongs properly to the range, though situated 

 six miles to the east of it. The limestone may be seen for a distance of four to five 

 miles, dipping under Mount Washington, showing that this part, at least, of the Taconic 

 range is a synclinal; and Graylock was long since shown to be a synclinal by Em- 

 mons. Each is a great mass of mica slate, or hydromica slate, partly chloritie, held 

 up in a very broad trough of limestone. In other parts, the range is a narrow and steep 

 synclinal, like the south end of Tom Ball. For other sections of this broken, upturned 

 and crystallized region of Green Mountain rocks, see a Memoir by the Author in Vols. 

 IV., V., and VI. of the American Journal of Science (1872, 1873). Between this 

 region and the Hudson River, the slates and limestones all dip eastward ; and the rocks 

 are probably, for the most part, of the Quebec group (Logan). What faults there may 

 be over the region has not yet been ascertained. 



(b.) Crystallization of the rocks. — The strata, as already implied, 

 were once beds of sand, mud, clay, or pebbles — or sandstones, argilla- 

 ceous sandstones, shales, and conglomerates — besides limestones, and 

 all may have contained fossils, while some were unquestionably full of 

 them. They are now crystalline or metamorphic rocks, — gneiss, 

 granyte, mica schist, hydromica slate, chlorite slate, quartzyte, crystal- 

 line limestone, etc. The sandstones, shales, etc., were made out of 

 older gneiss, mica schist, etc. ; and in this era of metamorphism they 

 were turned again into gneiss, mica schist, etc. 



The degree of crystallization over the Green Mountain region 

 diminishes west of Connecticut and Massachusetts, the limestone out- 

 cropping west of the New England boundary being generally little 

 crystalline, and the schists mostly ordinary argillyte. It diminishes 

 also northward, along the Green Mountains, toward Canada. 



(c.) Extensive fractures and faults. — The most remarkable of all 

 the fractures and faults is that which occurred near the western bound- 

 ary of the region of disturbance, and brought up the Quebec rocks on 

 the east side of the fracture to a level with the Hudson river shales 

 or Trenton limestone on the west, as made out by Logan. From 

 Quebec, it extends west of south, along western Vermont (passing from 

 Wey bridge by southern Sudbury), crosses Washington County, N. Y., 

 approaches the Hudson River near Albany, crosses the river not far 

 from Rhinebeck, fifteen miles north of Poughkeej:>sie, and continues 

 on southward into New Jersey. There may have been many inter- 

 ruptions and shifts along the course of this fault ; but the fact of its 

 essential continuation throughout all this distance is well substantiated 

 by observed facts. The line of it apparently runs into another series, 

 which extends through Pennsylvania and Virginia (according to 

 Rogers and Lesley), and through eastern Tennessee (SafFord) and 

 northern Georgia, to Alabama. But the principal part of this latter 

 series dates from the epoch of the Appalachian disturbance, following 

 the Carboniferous joeriod ; for the Coal-measures in some places make 

 one side of the fault. 



