154 



sandstone, varying but little from its ordinary colour and being 

 only rather more compact, contains a multitude of the large 

 spheroidal nodules of pure green epidote, many of which are at 

 least an inch in diameter. They seem not to be distributed pro- 

 miscuously through the rock, but to be arranged somewhat in 

 layers, parallel to the planes of the strata, though they are often 

 several inches asunder. Two or three hundred feet nearer to 

 the trap, we find the rock darker and harder, and the number of 

 nodules greatly augmented, though they are generally of much 

 smaller size. The common colour of the rock is here a very 

 dull purplish blue, and that of the included nodules a dull black 

 or a deep blue. They are of all sizes, from minute specks to the 

 dimensions of a large hazle-nut, and possess every shade of 

 distinctness contrasted with the material enclosing them. They 

 seem to consist of some imperfectly formed mineral, apparently 

 tourmaline in a semi-crystalline state. These spherical nodules 

 or specks, are oftentimes surrounded by a crust or coating of 

 another material, usually nearly white; and I have remarked that 

 the more obviously formed this crust appears, the more crystal- 

 line or fully developed is the interior kernel, which, at this spot, 

 seems to approximate in its features to black schorl or tourma- 

 line. A few hundred feet nearer to the trap, or almost at its 

 base, the rock presents a still different aspect, being of a dark 

 gray hue, and somewhat coarse-grained. It seems to have been 

 a sandstone, containing little or no clay, as it has nothing at all of 

 the baked jaspery texture of that previously described, which has 

 plainly been either a shale or a very argillaceous sandstone. This 

 gray rock is speckled with innumerable small crystals of very 

 regularly formed tourmalines, some of which are more than half 

 an inch in diameter. Upon the opposite side of the river, below 

 New Hope, we meet with very nearly the same order of things, 

 except that the rock containing the completely formed tourma- 

 lines is absent. 



In one thin layer of the altered red argillaceous rock on the 

 Pennsylvania side, the mass, which is of a pink hue, contains, 

 blended with the crystallized epidote, some minute but perfectly 

 formed crystals of a mineral, apparently idocrase, of a beautiful 

 wine colour. 



The altered belt here described, ranges northeastward from 



