266 Address before the Association of American Geologists. 



river on both sides, at least through a considerable part of its 

 coarse ; and there is evidence, also, that an extensive fault in the 

 primary rocks runs through that valley. Prof. Mather describes 

 "a line of fracture and anticlinal axis" as passing a little west of 

 the Hudson river, as well as numerous joints and fractures in the 

 valley of the Hudson, which not improbably may be a valley of 

 dislocation. Indeed, I doubt not that in most of those cases 

 where rivers have found their way through gorges of lofty and 

 precipitous ridges, it will be discovered that a break previously 

 existed in the strata. To give an example : — the great western 

 railroad, leading from Boston to Buffalo, and destined, ere long, to 

 reach St. Louis, and ultimately perhaps the Pacific Ocean, is car- 

 ried across the Hoosac range of mountains through a deep cut 

 made across the ridges by Westfield river ; and in no other place, 

 probably, could it have been carried through. But I have re- 

 cently satisfied myself that the course of that river was deter- 

 mined for a considerable distance, at least, by the existence of a 

 wide fissure in the primary strata, which was subsequently filled 

 in part by an enormous vein of granite. Is not this a beautiful 

 example of prospective benevolence on the part of the Deity, 

 thus, by means of a violent fracture of primary mountains, to pro- 

 vide for easy intercommunication through alpine regions, count- 

 less ages afterwards ! 



These slight sketches are sufficient to show that the great and 

 striking features of our country are dependant upon a few extend- 

 ed axes of elevation and depression ; and that probably subordi- 

 nate anticlinal and synclinal lines will be found connected with 

 most of the minor features of our surface. To trace them all 

 out will be a great, yet most interesting work ; as it will be to 

 ascertain the systems of strata connected with them. Of the 

 latter, we have in New England no less than five or six distinctly 

 marked. They are all of them of ancient date, and most of them 

 very ancient. The oldest, which may be called the oldest meri- 

 dional system, because it runs not far from north and south, is 

 composed chiefly of gneiss and mica slate ; and crosses Massa- 

 chusetts near its centre, including, although this is not certain, 

 probably the most elevated land in New England. The second, 

 which I call the northeast and southwest system, because it runs 

 in that direction, is more distinctly marked than any other ; hav- 

 ing a high and uniform northwesterly dip. It corresponds in 



