4 BULLETIN OF THE 



has a breadth little less than 1,000 feet, the whole of which forms 

 a single mass of ore, with occasional thin strata of imperfect chert 

 and jasper, and dips north 10 degrees, east about 30 degrees. At its 

 southerly outcrop, the ore is exposed in a low cliff, above which the 

 hill rises to the height of 20 or 30 feet above the country on the 

 south. The ore here exhibits a stratified or laminated structure, and 

 breaks readily into sub-rhomboidal fragments, in such a manner as will 

 greatly facilitate the operation of quarrying or mining the ore. This 

 bed of iron will compare favorably, both for extent and quality, with 

 any known in our country." (p. 22.) The sandstone is said to be found 

 frequently "surrounding, and in contact with, the uplifted masses of 

 igneous rocks, and is then invariably much altered both in appearance 

 and textiu'es, and may, under such circumstances, fairly be considered as 

 metamorphic." (p. 23.) 



In the report of Mr. A. B. Gray to the Ordnance Bureau,* galena and 

 copper pyrites were said to exist quite abundantly, and that it was prob- 

 able that rich tin ores would be found. Mr. Samuel Peck is credited with 

 having first explored the iron region, and called attention to the exist- 

 ence of that mineral {I. c, pp. 15, IG). 



Prof H. D. Rogers t stated that the rocks in the vicinity of the 

 Chocolate and Carp Rivers (Hvironian of Brooks) were " the equivalents 

 undoubtedly of the Primal sandstone and Primal slate," or the Potsdam 

 sandstone of the New York survey. 



Mr. William A. Burt, in his report " with reference to mines and 

 minerals for 1846,":}: (pp. 849-852,) described "fourteen beds of mag- 

 netic iron ore " in this district. Mr. Bela Hubbard in his report for the 

 same year {I. c, pp. 901 - 905) advances some views upon the passage of 

 one rock into another, as follows : " A feature peculiar to all the rocks of 

 the country alluded to as granitic, is their occasional trappose character, 

 and the rare occurrence of mica. The constituents which make up the 

 greater part are quartz, felspar, and hornblende ; the proportions of 

 which vary extremely. Thus, while the general character is that of true 

 sienite, the absence of quartz in a distinct form often produces a green- 

 stone, while frequently the last-mentioned mineral predominates almost 

 exclusively, constituting a true hornblende rock, which is generally of 

 a crystalline structure, and usually has a slaty cleavage. Again, quartz 



* Executive Documents, 29tli Cong. 1st Sess.,.Vol. VII., No. 211, 1845-46, pp. 

 2-23. Am. Jour. Sci., (2,) Vol. V., 1848, p. 151. 

 t Proc. Bost. See. Nat. Hist., April 1st, 1846, II. 125. 

 X Senate Documents, 31st Cong. 1st Sess., 1849-50, III. 371-935. 



