174 SIDNEY POWERS 



subjected to high temperature for a long period of time, as long 

 tongues of granite run out into the dike-rock. In other cases merely 

 remnants of inclusions over a foot in diameter are left, the greater 

 part of the volume of the original block being filled with kera- 

 tophyre mixed with the feldspars from the inclusion. 



The origin of the inclusions of the igneous rocks must have 

 been at some distance below the present .exposure. No brecciation 

 of the slate is observable at the surface, so it is thought that the 

 inclusions of slate, which are often 2-foot cubes, and quartz, which 

 are always small, also came from some depth, but not from such a 

 distance as the igneous rocks. It is not known to the writer whether 

 syenites, apHtic granites, and graphic granite outcrop farther inland 

 or not. At Wells, 7 miles to the north, biotite granite is quarried. 



The manner in which the inclusions of igneous rock, and possibly 

 those of slate and quartz, were obtained is apparently by shattering, 

 probably along the walls of the feeders of the sills. The resorption 

 of the edges of the blocks must have been begun in depth where 

 there was sufficient heat to assimilate a large part of an originally 

 cubical block over i cubic foot in volume. However, as pointed 

 out in other cases, if these blocks were shot up to their present posi- 

 tion, the resorbed edges would be worn off; if they floated up, the 

 resorbed edges would be partly preserved. Therefore, it is neces- 

 sary to assume that the temperature of both the inclusions and 

 the sill was nearly the same and that the corrosive action continued 

 for some time after the blocks were at about their present levels, 

 due to an additional supply of heat from below. This hypothesis 

 is supported by the fact that where the margins of the sill are 

 chilled, the inclusions in the marginal zones and also the more 

 abundant inclusions in the center of the dike show fused contacts, 

 but not extensive resorption. On the contrary, where there are no 

 chilled margins, indicating that this part of the dike remained hot 

 longer than the rest and then consolidated at one time, the inclu- 

 sions all show resorption and assimilation and only skeletons are 

 left of some of them. As the sill is of aschistic composition, such 

 heating action is thought to be possible. 



Rossland, British Columbia: During the C2 excursion of the 

 International Geological Congress last summer, an inclusion- 



