GEOLOGICAL EXPLORATIONS AND LITERATURE— 1850. 19 



(p. 834). Between the northern and southern granite areas Hes the 

 region of nietamorphic rocks. Tliis region is divided into two parts — 

 the southern or qnartzite portion, and the northern or trappean portion, 

 corresponding to our present division into tlie fragmentals and greenstone- 

 schists. In the southern area are found white and In-own quartz rocks, 

 talcose and augitic slates and clay-slates, slaty hornblende, and specular 

 and micaceous oxides of iron. These rocks cover a tract of country 1}' iug 

 "between the granites on the south and a line bearing north of west from 

 the mouth of Carp River to the center of the west line of township 48, 

 range 26." This tract is described as rolling, with numerous ridges trend- 

 ing nearly east and west. The central portions of many of the ridges 

 seem to be trap, which is capped and flanked by the metamorphosed 

 rocks. No outcrops of this trap Avere seen, however. Its presence was 

 inferred from the character of the metamorphic rocks and their dips, which 

 were thought to be in all directions away from a central axis. All the 

 metamorphic rocks are pervaded by "the oxides of iron, sometimes inti- 

 mately disseminated, and sometimes in beds or veins," which are frequently 

 of such "great extent as almost to entitle them to be considered as rocks." 

 The ores are described, and the positions of some of these outcrojDS are 

 noted. The northern portion of the metamoqihic area embraces all the 

 country between the quartzite grou]) just described aud the granites to 

 the north, with the exception of aboiit 5 square miles in the northeast part 

 of T. 48 N., R. 26 "VY., where clay-slates occur. "This division of the meta- 

 morphic region is characterized by the frequent occurrence of knobs or 

 uplifts of greenstone and augitic trap, making their appearance rather 

 irregularly over the country, and suiTounded by altered sandstones and 

 slates." The greenstone is igneous in origin. 



This report of Hubbard's is by far the most satisfactory one published 

 up to this time. It supplements Houghton's general rejjort of 1841, and 

 for the first time gives a fair idea of the character of the counti-y n(iw 

 included in the Marquette area, the distribution of the rocks occupying the 

 district, and their relations to one another. Of course the report is frag- 

 mentary. The author regarded it as such, and yet it contains in shadowy 

 outline mauA* of the conclusions of later g-eolog'ists. 



