264 EDWARD STEIDTMAN 



shows a drag toward the south, it is concluded that the south wall 

 has dropped with reference to the north wall. The amount of lateral 

 or vertical displacement is not known, but these movements have 

 very likely been small since the lateral extension of the shear zone 

 appears to be very limited. 



RESUME OF THE SECONDARY STRUCTURES 



The cleavage and a minority of the joints of the pre-Cambrian 

 rocks exposed on the eastern end of the Baraboo quartzite range 

 are related to the folding of the range. On the South Range, about 

 20 per cent, of the joints, and on the North Range, about 40 per cent, 

 are related to the folding. 



Many of the joints of the pre-Cambrian are independent of the 

 folding, having been developed in part before the deposition of the 

 Cambrian, and in part after the deposition of the Cambrian. About 

 80 per cent, of the joints of the South Range and 60 per cent, of those 

 of the North Range are unrelated to the folding. 



THE MECHANICS OF THE SECONDARY STRUCTURES OF THE EASTERN 

 PART OF THE BARABOO QUARTZITE RANGE 



It is evident from the description of the secondary structures of 

 the Baraboo quartzite range that there are two distinct types of joints 

 present. The joints of the predominant type, comprising about 80 

 per cent, of the joints of the South Range, and about 60 per cent, 

 of the joints of the North Range, are independent in their strike, 

 dip, and space relations of the quartzite formation. They were not 

 produced by the folding of the range, but by later deformations. 

 Another type of joints, comprising about 20 per cent, of the joints 

 of the South Range, and 40 per cent, of the joints of the North Range, 

 are connected with the folding of the range. They are the vertical and 

 north-dipping discontinuous, diagonal strike joints, and the bedding 

 joints of the South Range, and the bedding joints and the nearly 

 horizontal strike joints of the North Range. The two types will be 

 given separate attention. 



THE SECONDARY STRUCTURES PRODUCED BY THE FOLDING OF THE RANGE 



The folding of the quartzite formation was accomplished by slipping 

 between the beds, by fracturing, and by the flowing of the beds. 



