INTERESTING LOOALITIES OF TUE ISOPEMING FOItMATION. 425 



mtermediate points (Atlas Sheets XVIII and XXII). Ilei-e the rocks are 

 for the most part typical quartzites, although at one jjlace interstratified 

 graywacke is seen. The basal portion of the r[aartzite is a conglomerate, 

 bearing detritus from the Negaunee formation. 



Lake Corning area. — Tlio Hext sot of exposurcs, lu sccs. 4, 5, and 6, T. 47 N., 

 R. 27 W., occur at intervals west of the Excelsior mine to a point al)out 

 2 miles east (Atlas Sheets XXV and XXVIII). At the basal horizon there 

 is here again a conglomerate, the debris of which is chiefly from the 

 Negamiee formation; the ordinary varieties of the formation, however, are 

 the typical quartzites, but with these are slaty phases. 



ishpeming area. — The uext important localities are those at Ishpeming and 

 in the various basins south of Ishpeming. At nearly all of the mines 

 adjacent to this city the contact between the Negaunee formation and the 

 Goodrich quartzite is seen. East of Ishpeming the conglomerate at the 

 contact is found at the large open pit of the Lake Superior mine and in 

 open pits in the bays both to the north and south. At the first of these the 

 contact between the Ishpeming formation and the Negaunee formation 

 makes the so-called Lake Superior "W." (PI. XVI.) 



South of Ishpeming, the conglomerate is again seen in the large open 

 pit near the east quarter post oi sec. 9, at open pits north of the green- 

 stone bluff in the SE. ^ of the section, and at numerous localities at the 

 large open pits in the SW. J sec. 16. In the localities nearest the city of 

 Ishpeming the conglomerate usually rests upon the Negaunee formation, 

 but on the south slope of the greenstone bluff, adjacent to the section line 

 between sees. 3 and 10, the conglomerate rests upon the greenstone. The 

 same relations are seen in the southeast part of sec. 16, in the large open 

 pit just south of the east-west quarter line. 



South of this locality, in the SW. 5 sec. 16, are the handsomest expos- 

 ures of this conglomerate in the Ishpeming area. The rock occupies a 

 well-marked ridge parallel to the railroad. Upon its smooth glaciated 

 surface it presents a beautiful appearance, due to the pebbles of brilliant 

 red jaspei". 



The basal phase of the conglomerate for the Ishpeming area is usually 

 very feiTUginous (PL XXVII, fig. 2), and where it is fine-grained it may 



