PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 823 



Graywacke. Quartz-feldspar schist.] 



Mic. This is so micaceous and fine and so charged with calcite that it might 

 almost be styled a sericitic schist. Still there are crystal forms of feldspar as well 

 as quartz well preserved. One section. 



Age. Pebble in Upper Keewatin. N. H. w. 



No. 2016. GRAYWACKE. 



From the same place as No. 2013, but further south on the point. 

 Ref. Annual Report, xxiv, page 12. 



Meg. From the country rock at large. 



Mic. This is a clastic made up of small pebbles of rock like the foregoing pebbles, 

 and of feldspar and quartz crystals, embraced in a finer debris of the same kind, the 

 whole much altered. This rock presents an interesting contrast with the foregoing 

 pebbles which have a general similarity and can be referred to the same general 

 source. This is plainly a composite rock. One section. 



Age. Upper Keewatin. 



Remark. The feldspars in this fragmental are obscured and often nearly lost 

 by the introduction of fine granular substances. This change is akin to that seen in 

 the alteration of feldspars in the Ogishke conglomerate. N. H. w. 



No. 2017. QUARTZ-FELDSPAR SCHIST. 



From the same place as No. 2016. 

 Ref. Annual Report, xxiv, page 13. 



Meg. A pebble from the conglomerate. 



Mic. This slide is like No. 2013, etc. The feldspars, however, are not so well 

 preserved. The rock is evidently of the same nature and origin. Appears to be a 

 clastic rock. One section. 



Age. Pebble in Upper Keewatin. N. H. w. 



No. 2018. QUARTZ-FELDSPAR SCHIST. 



Same place as No. 2016. 



Ref. Annual Report, xxiv, page 13. 



Pebbles from the same. 



Mic. This pebble has considerable quartz in the fine matrix surrounding the 

 feldspars, and the feldspars are nearly destroyed. There are areas evidently once 

 occupied by feldspars that are hardly separable from the surrounding rock material. 

 They show sometimes a greater or a smaller number of microlitic secondary particles, 

 or the particles are larger, or arranged in lines at variance with the surrounding 

 rock; and sometimes such secondary particles appear as if somewhat dependent on 

 the direction of original cleavages in the feldspar which has been lost. One 

 section. 



Age. Pebble in Upper Keewatin. N. H. w. 



