196 BULLETIN 109, UNITED STATES NATIONAL MUSEUM. 



the same, except that in some places it contains more mica." Its 

 dip is north northwest. 



The report compiled by Mr, Hubbard treats the general subject 

 under the following subdivisions: Granite rocks; Metamorphid 

 Group; Clay slate; Red sandrock'; Keweenaw Point; Trap rocks; 

 Conglomerate rock; Mixed conglomerate and sandstone; Trap dikes; 

 Red sandrock; and Mineral veins. 



In the primary region west of Presque Isle the granite " is traversed 

 by large and irregular dikes of greenstone trap, and the granite itself 

 puts on a trappose character, the two rocks being sometimes with 

 difficulty distinguishable from each other." 



The metamorphic group is divided into two belts — a quartzose 

 portion on the south, and a trappose portion on the north. The 

 quartzose rocks are pervaded by argillaceous red and micaceous 

 oxides of iron. 



These are frequently of so great extent as almost to entitle them to be con- 

 sidered as rocks. The hirgest extent of iron noticed is in township 47 north, 

 range 26 west, near the corner of sections 29, 30, 31, 32. There are here two largt 

 beds or hills of ore, made up almost entirely of granulated magnetic and specular 

 iron, with small quantities of spathose and micaceous iron. The more north- 

 erly of these hills extends in a direction nearly east and west for at least one- 

 fourth of a mile, and has a breadth little less than 1,000 feet, the whole of which 

 forms a single mass of ore. 



This was the first discovery of the vast deposits of iron in the 

 Marquette region at Negaunee and Ishpeming. It was in June, 1845, 

 during a survey under the direction of Doctor Houghton, with Wil- 

 liam A. Burt as chief assistant. 



"The rocks of the metamorphic group frequently graduate into 

 clay slate." This is found in township 48, north 26 west. 



Mount Houghton is the name bestowed on a knob of traj) 878 feet 

 above Lake Superior, in the southerly range of Keweenaw Point in 

 township 58, north 29 west. 



Tlie red sandrock is in this report pronounced " the equivalent of 

 the Potsdam red sandstone of the New York reports." 



The study of the mineral veins confirms the views previously ex- 

 pressed by Doctor Houghton. Their courses are nearly at right 

 angles to the line of bearing of the trap range. 



In closing, Mr, Hubbard regrets the meagerness of his sketch 

 " when compared with whateA'er proceeded from that master mind 

 whose genius first developed, and whose indomitable energy tracked 

 through all its difficulties, a system not only intricate in itself, but 

 noA'el to science; and in a region at that time destitute of all the ordi- 

 nary facilities for scientific investigation. To the same active and 

 philosophic mind we owe the system of the union of geological witli 



