482 THE MAEQUETTE IKON-BEAlilNG DISTEICT. 



uniformly to the north at varying angles. These conglomerates are inter- 

 bedded with wide or narrow bands of a fine or coarse gi-ained graywacke 

 or quartzitic rock, sometimes the conglomerate and sometimes the sedi- 

 mentary rock being in excess. The matrix of the conglomerate is often 

 coarsely crystalline, with a very rough, dark-green, weathered surface. 

 The roughness is caused by the projection of numerous hornblende crystals 

 beyond the general surface of weathering. The latter is often dark-gra}^, 

 like that of the interbedded graywacke. Often bands of the graywacke 

 and bands of the amphibole-bearing rock alternate, forming together the 

 matrix in which the fragments are embedded. At other times the matrix is 

 a brilliantly black hornblende-schist or biotite-schist. The pebbles and 

 bowlders embedded in this matrix are sometimes waterworn, but oftener 

 they are sharply angular. The rounded fragments are principally quartz- 

 ites and griinerite-schists, and the angular ones are similar in composition 

 to the graywacke interbedded with the greenstone-conglomerates. On the 

 weathered surfaces the contact between the pebbles and the matrix is sharp 

 and clear, but on the fresh fracture the materials of jjebble and matrix appear 

 to grade into each other. On the north side of the hill the interbanding of 

 the light- weathering graywacke and a dark-weathering "greenstone" is well 

 shown. The dark rock is composed almost exclusively of hornblende and 

 garnets. In the hand specimens it appears thoroughly crystalline, but in 

 thin section there are seen numerous grains of quartz which appear to be 

 of clastic origin. Both the graywacke and the greenstone become con- 

 glomeratic at times, the former containing pebbles and large bowlders of 

 the latter rock, and this in turn containing bowlders of the graywacke. 

 All the beds at this place are much contorted, and often they are crossed 

 by numerous faults with small throws. 



On the top and along the south side of the ridge in the northern part 

 of the section the conglomeratic rocks are beautifully exposed. Here great 

 flat surfaces exhibit a strikingly handsome brecciated structure. The inter- 

 banding of the graywacke and the dark rock is not so plain here, although 

 fragments showing the interbanded rocks are met with embedded in other 

 rocks. Large irregular fragments of a black schistose rock, like the matrix 

 of the conglomerate near the west quarter post of the section, are found 



