1884.] 23 [Crosby. 



lines of finer and coarser sediments coinciding with the cleavage, 

 but we could not find any indication of them. 



The development of the cleavage has nearly effaced the origi- 

 nal structure lines of this part of the conglomerate; but indubi- 

 table traces of the bedding still remain. On both sides of the 

 avenue, but especially on the southeast side, there are thin beds 

 of purplish slate in the conglomerate, and also layers of coarser 

 and finer pebbles, all showing a very high dip to the southeast. 

 The avenue runs S. 35° W., and the strike makes an angle of 

 about 10' with the avenue, being southwest, and not east-west, as 

 Dr. Wadsworth claims. The entire independence of the stratifi- 

 cation and cleavage is apparent even in hand specimens of the 

 conglomerate. At the ledge of sandstone and breccia further to 

 the southwest on the avenue, the stratification, as Dr. Wadsworth 

 truly says, is remarkably distinct. But it passes my comprehen- 

 sion how he could find the line of strike here to be east-west ; 

 and I am confident that he would not should he again visit the 

 locality. There is simply no room for a difference of opinion 

 here, but the facts clearly sustain my original statement that the 

 strike is S. 45° W. and the dip S. E. about 75°, both being 

 entirely at variance with the cleavage. 



Finally, the large, angular fragments in the breccia do not 

 resemble the slate on the railroad, nor any other slate occurring 

 in that region, so far as I have observed. The slate forming the 

 anticlinal on the railroad is greenish gray and so distinctly and 

 finely stratified that one could scarcely obtain a fragment three 

 inches in diameter that would not show the bedding lines. But 

 the fragments in the breccia are of a very dark grayish black 

 color, and, although they are very numerous and the largest are 

 two feet in diameter, yet none of them show the slightest trace 

 of bedding. They have the general aspect of slate, but the micro- 

 scopic examination of thin sections shows that they are probably 

 a highly altered eruptive rock or trap. Large ledges of compact 

 and slaty trap occur all about the breccia, and many of the dike 

 rocks of this vicinity are of similar appearance to the fragments 

 in question, and are not easily distinguished from slate. Hence 

 it cannot be claimed that these fragments prove the post-Primor- 

 dial age of the breccia. 



In the same paper, Dr. Wadsworth, after noting the generally 



