.">(> CHAMPLAIN DIVISION 



the primary. This statement has proved true. On page -J:?0 of the Report for the Bame 

 r, it will be found that a sandstone in Essex count] was determined to be the same as 

 the Potsdam, and that il is succeeded by the Calciferous Bandrock of Baton. 



The V w-York system commences, then, with the Potsdam sandstone j a rock far from 

 being homogeneous in its composition, bul consisting mainlj of three portions, b conglo- 

 merate ;ii base, an even-bedded sandstone in the middle portions, and a mass of siliceous 

 dark-colored slate with fucoids at the superior portion. Its lithological characters arc not 

 uniformly the Bame. The conglomerate is Bometimes wanting, or is imperfectly deve- 

 loped, and 11 also contains irregular beds of breccia in which then- arc masses of grey 

 mentary limestone; a fact which is not to be forgotten. Beside-, these, there is a 

 mass of coarse dark-colored sandstone, traversed or checked bj thin scams of grey quartz. 

 This las) mass is well developed toward Champlainin Clinton county. The conglome- 

 rate along the Provincial line of New-York and Canada Bast, is more than three hundred 

 feet thick. This thick mass thins rapidly southwardly : and in the valley of the Mohawk, 

 the entire mass "i Bandstone, as well as the conglomerate, has disappeared. In the 

 absence of the Potsdam Bandstone, the succeeding rock, the Calciferous Bandstone, rests 

 frequently upon the Primary system, as at Littlefalls. The fossils of this rock arc fucoids, 

 nnd a single species <<( IAngula : the latter are in greal abundance al the High bridge near 

 ichester upon the Ansable. The same shell occurs at French creek upon the St. 

 Lawrence. 



The rock succeeding 'lie Potsdam sandstone, is. as has alreaih been Stated, the Culrifi 

 rous sandrock of the late Prof. Baton. This too, is one extremely heterogeneous in its 

 composition; consisting of a grey sandy limestone, a whin- hut quite siliceous limestone, 

 two or three encrinal masses which are nearly pure limestones, anil often with layers fit 

 for polishing, and winch form a tolerable handsome reddish marble. The most extraor- 

 dinary mass, however, is a reddish Bandstone, with thin inconsiderable layers of slaty 

 lamina-: if traced upward, it becomes a tolerably pure limestone, stained slightly with 

 iron, bul sometimes white. Layers from eighteen inches to two feet thick of Mack chert 

 ■l appear, and alternate with the grey sandy variety. In addition to the ahove, we 

 frequently meet with layers charged with fine quartz chrystals, intermixed with calc spar, 

 sulphate of harytes, sulpliuret of iron. etc. 



Another mass, the place of which i* very doubtful, is a brownish tough sandstone, 

 lying beneath all the other masses composing the Calciferous sandstone. The question in 

 rd to tliis mass, is whether ii is to be considered as an equivalent of the Potsdam 

 Istone, or as belonging to the succeeding mass, the Calciferous Bandstone. The deter- 

 mination of this question is, however, <>f do importance to the subject under discussion; 

 yet the mass s in a few places an important rock, as at Mount Toby in Washington 

 county, where it is one or two hundred feet thick. This, together with the red sandstone 

 just spoken of, I am Bometimes disposed to consider as equivalents of the Potsdam sand- 

 stone. Perhaps it would be better, however, to regard them as intermediate masses, so 

 long as there an- do decisive chat u ten on either sale. 



