434 Expedition to the 



appearance. It is the lowest, and is considered the most an- 

 cient of the' rocks containing organic remains. 



Geographical Distribution. — This rock occurs extensively 

 along all the northwestern side of the primitive of the AUe- 

 ghanies. In Lower Canada and Vermont, it is accompanied 

 by granular limestone, and granular quartz, which separate 

 it from the mica slate and talcose rocks on the east.* It is 

 there usually inclined towards the west at an inconsiderable 

 angle. It is separated from the compact floetz limestone of 

 the valley of Lake Champlain, by a stratum of old red sand- 

 stone which forms the upper part of a range of hills called in 

 Vermont, the Snake Mowitain. In Berkshire county, in the 

 western part of Massachusetts, and along the eastern side of 

 the Hudson in N<;w York, a stratum of primitive clay-slate 

 intervenes between this rock and the granular limestone. 

 The New Lebanon Mountain, which is of slate, and divides 

 the primitive limestone of Pittsfield, Richmond, Stockbridge, 

 &c. from the transition v/hich occurs at New Lebanon 

 Springs, and along the western base of this range, is consi- 

 dered primitive.! 



To the northeast of the Hudson river, the transition lime- 

 stone, nowhere occupies any great extent of surface from 

 east to west, but is a narrow strip running along the margin 

 of the primitive, and in a few miles is succeeded either by 

 red sandstone or clay slate resting upon it. In Vermont, in 

 the same neighbourhood, it alternates with clay slate and sup- 

 ports red sandstone. 



Crossing the Hudson above the Highlands, and proceeding 

 southwest, little of this stratum is seen, in the lower part of 

 New York, but it becomes more abundant in the western 

 parts of New Jersey and Pennsylvania. If we suppose the 

 whole of the Alleghany Mountains of Pennsylvania, Mary- 

 land, and the western parts of Virginia, removed to a level 

 with the surface at the base of their eastern declivities, it is 

 probable their foundation which would be thus exposed, would 

 be found through their whole extent, to be of transition lime- 

 stone. This rock is almost the only one which occurs be- 

 tween the primitive limestone about twenty miles west of 

 Philadelphia and Harrisburgh. Cove hill, the north and 

 south mountains, and the other eastern ridges of the Alle- 

 ghany, are all based upon metalliferous limestone. It is seen 



* See Eaton's Index, p. 183. 2d. Ed. 



t Devyey, iu the American Journal, p. 337. 



