SOUDx\N FOEMATION. 



235 



nortli at angles ranging from 65° to 80°, and pitch to tlxe west at an angle 

 of 22° to 45°. As the result of this pitch, the deepest levels are farthest 

 west. The deepest shaft. 

 No. 8, was down 926 feet 

 at the thirteenth level in 

 1902. Fig. 13, taken from 

 Bacon's account referred 

 to above, is a cross sec- 

 tion through shaft No. 8, 

 showing the condition of 

 the Minnesota Company's 

 mine, presumably about 

 1893, the time of the pub- 

 lication of the article. It 

 shows the general arrange- 

 ment of the workings. The 

 ore bodies lie one above 

 the other, and are usually 

 separated from one another 

 by impervious basements 

 of "paint rock" or "soap 

 rock." Sometimes they 

 are partially surrounded 

 by material of the iron 

 formation proper, that is, 

 the jaspers, cherts, and 

 interbedded bands of hem- 

 atite. When first opened 

 up, the ore deposits were 

 exploited by means of 

 open pits. These were 

 carried down to a maxi- 

 mum depth of 150 feet, 

 when it was found advisable to begin underground mining. From a shaft 

 in the soap rock which forms the foot and hanging walls, crosscuts are run 



Fig. 13. — Cross section at No. S shaft, Soudan. Jlinn, 



