MOUNT G KEYLOCK. 



149 



traverse the thick quartz laminae. Microscopic sections across both schist 

 and quartz show the parallelism of the minute plications of the schist 

 with the adjoining quartz, and the cleavage planes of the former terminating- 

 at the quartz. There is at least one thick quartz lamina in and parallel 

 to the cleavage foliation. Through a large part of the more micaceous 

 portion of the ledge no stratification foliation is visible to the naked eye 

 or under the magnifying glass; and even under the microscope the mass 

 shows only a wedge-shaped structure, all the minute folia lying with 

 their axial planes either parallel to the cleavage foliation or at a very acute 

 angle to it. 



Fig. 49. — Southwest anil part of suuth side of schist ledge (Fig. 48), showing the relation of the two foliations. Area 

 15 • 8 ft. From a photograph. 



Fig. 49 represents the southwest side of the same ledge, together with 

 a portion of its southern side, and also shows the relations of the two folia- 

 tions. The behavior of the cleavage and stratification foliations, when in 

 proximity to a thick quartz lamina, is beautifully shown in Fig. 50, which 

 represents a section from a specimen from locality FS4, in Groodell hollow. 

 The general parallelism of the coarse quartz lamina to the minute plications 

 in the schist on either side of it and the cleavage planes arrested by the 

 quartz will be observed. The longitudinal cracks in the quartz are pos- 

 sibly due to strain, as are also the transverse cracks in the quartz lamina in 

 Fig. 40. 



These facts indicate that the dip of the stratification foliation may lie 



