54 Minnesota Academy of Science 



to the Mesabi range. It is my purpose to show you the great dif- 

 ferences between these ranges. We do not have to study the 

 Mesabi range very long before we learn that its rocks are younger 

 than the rocks of the Vermilion range, and that they lie non- 

 conformably on the vertical strata of the Vermilion range, and 

 almost in a horizontal attitude. This was illustrated in the section 

 shown, extending from Tower southward to the Gogebic range in 

 Wisconsin, and will be illustrated by several views that are to 

 follow. 



(12) At the Mahoning mine at Hibbing this photograph was 

 taken, about three years ago. It shows the north wall of the great 

 pit, consisting of hematite ore in thin strata. Notice the irregular 

 knotty structure of the thin strata. There is no sharp transition 

 between the ore and the rock, like that in the Vermilion range, but 

 the rock itself changes into ore, and the steam shovel shifts its 

 direction only when the grade of the ore is too low. Both ore and 

 rock are so soft that for the most part they can both be excavated 

 without blasting, though sometimes the ore is first shattered by a 

 powder blast. The steam shovel is then sufficient. 



