244: E. T. Long — Minor Faulting 



amount of offset, as measured in this case, is quite uni- 

 formly 6" on both faults. The junction of the two faults 

 with the joint plane has made a point of weakness in 

 which the creek has cut a miniature cave of a few inches 

 but in the absence of a brecciated zone and a decrease in 

 the offset of the joints in approaching the point of the 

 wedge it seems that the force applied must have been 

 oblique to the section exposed rather than parallel with it. 

 At the intersection of some of the joints with the upper 

 fault plane a curved surface has been developed on the 

 joint planes, suggesting a drag movement so often seen in 

 connection with faulting. The direction and amount of 

 offset is easily seen, owing to the presence of the joints, 

 and corresponds quite closely with the fault at the Falls. 

 The face of the bluff trending as it does N 73° E gives a 

 very small angle of about 11° between it and a section 

 along the strike of the structure of the region, the axis of 

 the main fold being taken at N 85° W. One would, there- 

 fore, expect as in the previous case that by far the largest 

 part of the movement would not be disclosed. As the 

 sluice ran at right angles to the bluff it was hoped that 

 some information in the third dimension might be gained 

 but the broken character of the shale had erased any evi- 

 dence if such ever existed. It was finally noticed that at 

 the intersection of one of the east-west and one of the 

 N8° E joints where crossed by the dipping fault plane 

 about two square inches of the surface of the fault were 

 exposed; this showed an unmistakable dip into the bank, 

 that is to the south, but the surface was too small and 

 poorly situated to get any accurate readings. However 

 the dip south was apparently not less than 8° at the line of 

 outcrop. Presuming that this dip continues, regardless 

 of what its angle may be, it doubtless ultimately joins the 

 horizontal fault, from which it seems likely that it is a 

 branch. This being the case we have here a transverse 

 section of the two faults rather than a longitudinal sec- 

 tion as at first appeared. The movement of the wedge 

 block was therefore not primarily in and eastward, but 

 was northward. The deviation to the west, of the forces 

 coming from the south which produced the faulting, plus 

 a slight torsional movement, would swing the joints out of 

 alignment to the extent of six inches and the compari- 

 tively mobile shale would accommodate itself to the 



