76 BULLETIN OF THE 



investigations be made to ascertain their relations to the associated 

 rocks. We would propose, therefore, that all the acidic eruptive rocks, 

 whose chemical and physical constitution carries them above the rhyo- 

 lites, should be designated as Jaspilites from lacrTris and Xidos in accord- 

 ance with a suggestion of Professor Whitney. 



Finally, so far as our work has gone, it shows that Messrs. Foster and 

 Whitney were right in their observations and conclusions, so far as it 

 relates to the geological structure of the country, or to the origin of the 

 rocks and ores, except the peridotite. To them and to them alone be- 

 longs the cz'edit of having done their work accurately, and as thoroughly 

 as the circumstances would allow, while the more recent observers 

 and writers, Kimball, Credner, Rivot, Hunt, Dana, Brooks, Lesley, Win- 

 ch ell, Newberry, Wright, and others, have held and pushed theories in 

 direct opposition to the facts, until a geologist who took a different view 

 was regarded either with pity or derision. As regards the general geol- 

 ogy of the country, we feel that Messrs. Foster and Whitney's writings 

 remain to-day the best and most accurate exponents. Considering the 

 difficulty of exploring the country thirty years ago compared with the 

 present, it is surprising how much they saw, how accurate their ob- 

 servations were, and how little has been added to our knowledge since ; 

 also how our knowledge and science have again retrograded, until geol- 

 ogists have gone back to the views of Messrs. Houghton, Hubbard, and 

 Locke. 



The Copper District. 



The earliest writer to advance any especial views regarding the cop- 

 per and its origin, so far as we are aware, was Henry R. Schoolcraft.* 

 He considers it probable that the masses of copper about the Onto- 

 nagon River were thrown out of volcanoes by volcanic action. The 

 mountains are said to be of granite (Porcupine Mountains) so far as 

 observed, and the sandstone to have been upheaved into a nearly vertical 

 position at their base by the elevation of the granite. He considers that 

 native copper will never be found in sufficient abundance to pay for 

 mining, but that probably " valuable mines of the sulphuret, the car- 

 bonate, and other profitable ores of copper," will be discovered. t 



In 182.3, in describing a supposed vein of malachite on Keweenaw 

 Point, he concludes "that the entire peninsula consists of a spine of 



» Am. .Tour. Sci., 1821, (1,) IIL 201-216. Quart. Jour. Sci. and Arts, London, 

 1822, XII. 422, 423. 

 t See also Senate Papers, 2d Sess., 17th Aug., 1822, Doc. 5. 



