172 



THE PENOKEE IRON-BEAKING SERIES. 



lower layers of tlie quartz-slate numerous t'rag'uients of the chert whieli 

 immediately uudei'lies it, and sometimes tlie rock becomes a recomposed 

 quartz rock, disting'uishable from the underlying forniatiou only by the 

 presence of a small portion of plainU' recog-nizable fragmental material. 

 These peculiar occurrences are taken to indicate that between the two 

 formations was a more or less extended erosion interval. The chert 

 fragments in tliese places occur both in basal conglomerates and in thin 

 bands interstratiiied with a noncong-lomeratic slate. As the contact is 

 receded from ilw chert fragments become very soon of smaller size, although 

 pieces of the same chert are occasi(mally microscopically recognizable even 

 in the higher horizons of the formation. 



Contacts with the Southern Complex. — At Potato river and West branch 

 of Montreal river the Qiiartz-slate member is seen in contact witli 

 greenish schists on the south. The Potato river junction is illustrated by Fig. 



Mai» (if i^\]>iisiires lit Potuto river. Sr.ile: 1 iin'li-'2fi4 foet. 



5, whidi shows tlic position of tlie various exposures, l^he river here has 

 a bold liauk some To feet in lieiylit, aloni;- the face of wliicli tlie contact 



