THE GKOVELAND FORMATIOiT. 447 



R. 31 W., and 3, T. 43 N., R. 31 W.; the exposures and test pits at the 

 Sholdeis exploration in sec. 21, T. 45 N., R. 31 W., and the test pits at the 

 Doane exploration in sec. 16, T. 45 N., R. 31 W. The last two localities 

 are 1 mile apart, and the more southern is 8 miles north of Michigamme 

 Mountain. 



In spite of the poverty of the formation in outcrops, its distribution 

 throughout the area has been well determined through its magnetic proper- 

 ties (following the methods described in Chapter II). Adjacent to the 

 Fence River area of the Hemlock formation it gives rise to a strong mag- 

 netic line which passes through the outcrops and test pits of the Sholdeis 

 and Doane explorations. To the north this line was followed to the south- 

 ern side of sec. 32, T. 46 N., R. 31 W., where it is said to connect with a 

 magnetic line followed by Mr. Clements from the western to the noi-thern 

 side of the Archean dome. To the south it continues into the Michigamme 

 Mountain area to within a mile of the outcrops of Michigamme Moun- 

 tain. There the magnetic line gives way to a broad zone of disturbances, 

 feeble and difficult to interpret, but consequent I believe mainly upon the 

 flattening of the formation as it begins to pass over the general northwest- 

 southeast anticlinal axis. This zone connects directly with the exposures 

 of Michigamme Mountain which produce similar irregular disturbances of 

 the needles and which visibly constitute a thin crumpled sheet, on the 

 whole but gently inclined. 



For the stretch of 13 miles just described the Groveland formation 

 occupies a continuous belt on the east side of the main anticlinal axis. In 

 the Fence River area it lies east of and u^Don the Hemlock formation, while 

 in the Michigamme Mountain area it holds the same relations to the Mans- 

 field formation. 



The eastern belt was not traced farther than a mile southeast of Michi- 

 gamme Mountain. In the central and southeastern portions of T. 43 N., 

 R. 31 W., however, in the direct prolongation of the anticlinal axis, we 

 found a broad belt of slight magnetic disturbance, along the western mar- 

 gin of which lie volcanic rocks, dipping west. In sec. 26, T. 43 N., R. 31 W., 

 this magnetic belt splits into two branches, one of which runs directly east 

 for a mile and then southeast indefinitely, wliile the other maintains a general 

 southerly course to the south line of the township. In section 26 large 



