3i6 H. C. COOKE 



less metamorphosed and recrystallized by the heat of the intrusive, 

 and converted into hornblende and biotite gneisses, occasionally 

 with development of some garnet. Dikes of granite and pegmatite 

 pierce the sediments, and some blocks of the latter are found 

 included in the granites often at considerable distances from the 

 contacts. The included blocks are in all phases of digestion from 

 sharp-angled fragments through phases in which the edges and 

 corners have been partially or completely dissolved to phases 

 in which the only remaining indication of a foreign mass is a 

 vaguely outlined patch of material more micaceous than the sur-_ 

 rounding granite. The contact of the granites and Timiskaming 

 is different in degree, though not in kind, from a granite-Keewatin 

 contact, in that it is a fairly sharp hne, instead of being a wide 

 zone of blocks of the older rock separated by dikes and masses of 

 intrusive. This is undoubtedly due to the influence of the bedding 

 of the Timiskaming series in controlling the intrusion. 



The principal granitic rocks known to intrude the Timiskaming 

 in Ontario are two: a grayish syenite in Lebel Township, and 

 various bodies of syenite porphyry. The syenite body in Lebel 

 Township is presumably, from its shape, a batholith; the por- 

 phyries may form fairly large batholithic masses, as in the case 

 of the large mass north of Larder Lake, but more commonly they 

 form smaller bodies the intrusion of which has been largely con- 

 trolled by the bedding of the Timiskaming. They tend therefore 

 to be sill-like in shape, although they may be observed to cut the 

 bedding in numerous places. The chemical and mineralogical 

 composition of the syenite batholith and the intrusive sills is so 

 similar that there can be little doubt that they are but different 

 forms of the same intrusive magma. The writer has not observed 

 the contact of the Timiskaming series and the batholith in Lebel 

 Township, but the mapping by the Bureau of Mines indicates that 

 it is of much the same nature as the granite contacts in northern 

 Quebec already described. The evidence of intrusion of the sills 

 is more difficult to obtain, since the sills had practically no recrys- 

 tallizing influence on the sediments, and rarely have a chilled 

 edge, include blocks of sediment, or send off dikes into the sedi- 

 ments. The best evidence of intrusion is the areal evidence, 



