36 



DESCRIPTIONS 



eighty miles. The borings at Ballston and Albany, about 

 forty miles apart, are made in the same layers of argillite ; and 

 carbonated water is found in both places. See Mrs. Griffith's 

 Essays. 



2. Quart- 8, FiRST Graywacke, is an aggregate of angular grains 

 tion, of quartzose sand, united by an argillaceous cement, ap- 



parently disintegrated clay slate, spangled with glimmering 

 scales ; and is never above the calciferous sand rock or me- 

 talliferous lime-rock. Subdivisions. Graywacke Slate, when 

 the grains are so fine as to give the rock a homogeneous ap- 

 pearance, and is susceptible of division, into thick or thin ta- 

 bles, by natural cleavages. Millstone grit and grey rubble* 

 when the grains are in part course, and more or less conglom. 

 erate, either white or grey, often very hard. Both subdivi- 

 sions are often coloured green by chlorite. 



Localities. The slate lies immediately on the inclined edg- 

 es of the argillite from Canada to Georgia. It is remarkably 

 curved and bent on the Mohawk, between the Cohoes and 

 Schenectady, at Saratoga Lake, and at the entrance of the 

 Delaware and Hudson canal. Millstone grit, the whole of 

 Shavvingunk Mts. Gray Rubble, the highest ridges between 

 Massachusetts line and the Hudson. Contents. Milky 

 quartz in the eastern part of Rensselaer county, accompanied 

 cakTpar^ with chlorite. Calcareous spar and disseminated anthracite 

 and dissem- (never in beds) throughout its whole extent. It becomes an 



inated an- 

 thracite, excellent quarry stone m many localities ; and in others it is 



brittle and irregular. Often red and sandy. 



2 Galea- ^' ^^^^^^ LiMEROcK, consists of Carbonate of lime, in- 

 reousforma- termediate in texture between granular and compact; and is 

 traversed by veins of calcareous spar. Subdivisions. Com- 

 pactj when the masses or blocks, between Ihe veins of spar 



* Rubble being an uncouth word, but too well established to be rejected, I 

 will state : that in common English it si;^nifies a hard grey stone, in roads, of a 

 spheroidiil form, which causes the rumbling and jolting of carriages, Kirvan 

 calls these stones, common graywacke, as opposed to graywacke slate. Se^ 

 Webster's Dictionary, 



