63 



NOTES ON THE ROCKS. 



KEEWATIN 



The Keewatin rocks, of the Cobalt area proper, 

 fall into four groups: (i) Basalts, (2) Diabases and 

 other basic rocks, (3) Acid intrusives, (4) Sediments. 

 Of these the basalts are the most common. The diabases 

 are also of common occurrence, although they are not so 





















,: H 



■■ ,:.. 





























...-. ■■'..■ 



-,•;■,:■■■-•. vV 



'$4\f* ^ 



■■ ■ . 



\ * -. ' 



.; ' '•■ , . ■ . 



?>■* - 





















hB 





















IhI 



- 



















Torsion cracks in Keewatin greenstone, Cobalt. 



widely distributed as the basalts. The acid intrusives are of 

 infrequent occurrence in the Cobalt area. Thev include 

 felsite, feldspar-porphyry and quartz-porphyry. The sedi- 

 ments grouped with the Keewatin include iron formation 

 (jaspilyte, chert and greywacke), graphite schists and 

 slates. 



Many of the basic, igneous rocks of the Keewatin have 

 been rendered schistose and their original character cannot 

 now be definitely determined. 



