and Geology of Lake Ontario. 273 



described by hira as an aggregate of angular grains of quartzose 

 sand, cemented by indurated clay, and generally containing 

 glimmering scales of mica and talc. A coarse variety called 

 Rubblestone (common grauwacke) is very hard, and contains 

 large pebbles and fragments of argillite, slaty grauwacke, &c. 

 Glimmering scales are rare, or wholly wanting in this variety. 

 Colour genei-ally gray.' — (G. S. p. 33.) 



This is a very prevalent rock in the east part of the State of 

 New York. West of the gneiss ranges of the Little Falls, it 

 runs along northerly from two to three miles S. W. from the Mo- 

 hawk, about the same distance S. of the west branch of Fish 

 Creek and of the Salmon River, xmtil it meets the S.E. coi'ner 

 of Lake Ontario. It thus forms a belt from 8 to 10 miles broad, 

 between die carboniferous limestone, and a stratum called by 

 our author " millstone grit," under which it is seen to pass 

 at Steel and Myer's Creeks, &c. 



The grauwacke (which I have never seen but in rolled 

 masses) underlies the Erie Canal for twenty miles east of Utica. 

 From the direction of its strata being nearly horizontal, or be- 

 ing in a very gradually descending inclined plane, Mr. Eaton 

 conjectures that it underlies at no great depth (from 5 to 800 

 feet) all the western part of the State of New York. It does 

 not appear in view, however, any where immediately adjoining 

 the Erie Canal, west of Utica. — (G. S. p. 85.) 



I am not aware of any foreign minerals having been met 

 with in this rock, near Lake Ontario. On the Hudson and Sus- 

 quehanna Rivers, sulphuret of lead and manganese have been 

 found in many places : anthracite-coal, near Troy. 



Millstone Grit, (a rock so named by Mr. E.,) rests upon this 

 grauwacke. He classes it with the English rock of that name, 

 supporting the coal-measures. It is a coarse, harsh, aggregate 

 of quartzose sand and pebbles, without cement. It is gray, or 

 yellowish, or reddish gray. — (G. S. p. 35.) 



It underlies the new red sandstone (the salifei'ous rock of 

 Mr. E.), and accompanies it wherever it crops-out. From ten 

 miles S. of Little Falls, all the way in a north-west direction 

 to the S.E. corner of Lake Ontario, and for fifty miles west 

 from the first-mentioned point. Wherever the " millstone grit 

 is laid bare in ravines, &c., we see the saliferous rock lying 

 immediately upon it." — (G. S. p. 97.) 



This stratum, when it appears in full thickness, is from forty 

 to sixty feet thick, in several perpendicular ledges. It does not 

 pass into or alternate with the grauwacke upon which it lies. 

 All the rocks, above it and accompanying it, are much harder 

 at and near where they crop-out, than in Oswego, Genessee, 



N.S. \o\.S.^o.2S. April \V,2d. 2N or 



