222 THE VERMILION IRON-BEARING DISTRICT. 



The plane of contact between the ore and tlie jasper agrees in general 

 with the contour of the basin (fig. 11). One noticeable feature is that this 

 plane of contact in the upper part of the basin dips on the south side to the 

 north, and on the north side of the basin to the south. The conditions, in 

 other words, are those of a normal syncline. As the deeper workings of 

 the mine are reached, however, this dip is found to be overturned, and upon 

 the north side the dip of the plane is to the north. It will be noticed that 

 the greatest depth of ore lies, as it normally should, in the center of the 

 basin. The ore follows up both the north and the south limbs of the 

 syncline; it goes higher, however, and is very much broader on the south 

 side than on the north side. This condition of occurrence is in accord with 

 the view held concerning the origin of the ore deposits, and will be referred 

 to below. The plane of contact between the jasper and the ore is 

 irregular in the extreme, no sharp line of demarcation existing between 

 them. As has already been intimated, the merchantable ore grades upward 

 into lean ore, which in its turn merges by imperceptible gradations into 

 the jasper, with very small quantities of interlaminated iron-ore bands. 

 Bodies of jasper varying from minute pieces up to large masses project 

 downward into the ore. Occasionally a horse of jasper is included in the 

 ore. Again, a body of ore will project upward across the line into the 

 jasper. Within this lean ore, or mixed ore and jasper, one can find pieces 

 of jasper showing partial change into the ore, the bandingof the jasper still 

 existing in a more or less perfect condition in the ore. There is in reality 

 no sharp line between the ore and the jasper, but there is a gradual 

 transition from one to the other. These facts will be referred to again 

 under the discussion of the origin of the ore deposits, on page 230. 



THE TOWER AND SOUDAN DEPOSITS. 



Let us now consider the ore deposits at Tower and Soudan. At these 

 places the conditions of occurrence are not nearly so simple as at Ely. In 

 the first place, the iron formation in the western part of the district has been 

 very much crumpled, and there appear to be many alternations of jasper and 

 a schistose green rock. The relations of the jasper and this green rock are 

 not in all places clearly shown. At some localities it appears that the green 

 rock is a greenstone belonging with the Ely greenstone, and hence the 

 basement on which the jasper rests. It owes its alternation with the 



