UPPER HUKONIAN. 377 



sec. 34, T. 65 N., R. 5 W., eastwai'd to the great cross valley in sec. 27, 

 T. 65 N., R. 4 W., the members of the series rest upon the older rocks 

 and uniformly dip to the south. The regularity of this dip is, however, 

 interrupted by a number of minoi- flexures whose axes plunge south- 

 southeast. As a I'esult, the amount of the dip varies considerably, ranging 

 from about 10° to 65° to the south, the higher dips occurring invariably 

 at the western end of the belt, the dips becoming flatter as the belt is 

 followed to the east. Moreovei', these dips vary rapidly within short dis- 

 tances. Likewise the strike, although in general following the trend of 

 the belt, is found to vary gradually within short distances. The uniform 

 dip to the south shows the very simple structure which prevails hi this belt, 

 but the changes in angle of dip and in strike clearly indicate the j^resence 

 of a number of subordinate rolls in these monoclinal southerly dipping 

 series of sediments. The gradual diminution in the angle of dip as the 

 sediments are followed to the east corresponds to the less folded condition 

 of these sediments in this part of the area. Attention has already been 

 called to the areal distribution of the sediments and the westward-trending 

 tongue of sediments occurring in sees. 21 and 22, T. 65 N., R. 4 W., which 

 is good evidence of an infolded syncline of these sediments at this place. 

 The dip of the sediments as observed upon the outcrops in this area gives 

 further proof of the occurrence of this syncline. 



In general, then, the sediments have a uniform dip to the south, with 

 minor irregularities, these irregularities being most marked in the western 

 part of the area and in general wherever the sediments lie against the 

 older rocks. Some very considerable irregularities have been noted in a 

 few cases along the margins of certain enormous masses of dolerite which 

 occur in the midst of the sedimentary area. These dolerites, it may be 

 stated here, are intrusive in the sediments, and this fact sufficiently explains 

 the contorted character of the sediments immediately adjacent to them, for 

 this contorted character is confined only to their immediate vicinity, the 

 uniform low southerly dip appearing by the time one has gone some 

 distance from such contact lines. 



PETROGRAPHIC CHARACTERS. 



The Gunflint iron-bearing rocks at the east end of the Vermilion district 

 correspond stratigraphically to, and are indeed the eastern continuation of, 

 the iron-bearing rocks of the Biwabik formation, which are so well developed 



