498 PROCEEDINGS OF SECTION C. 
east of the “Gift” and “Excelsior” lines, strikes 35 deg. east of 
north, but as it goes further north, to where the strike of the 
dyke would cut it, it has turned 45 deg. east of north. As the 
easterly lode formations tend to bend out of the prevailing course 
towards the east more than the westerly ones, I rather fancy this 
dyke will prove to die out about a mile east of the “ Excelsior” 
shaft, as the rocks are evidently strained there, but not sufficient 
to bring them to the breaking point. This dyke runs fairly 
parallel with the lay of the chief mountain spurs, and was formed 
after the lodes which it displaces; it was also sudden in its 
formation, to allow the molten rock to take its present position, 
and not slow like the lodes. 
I consider that the crystalline schists of Bethanga belong to 
the earliest sedimentary rocks, which were deposited mechanically, 
and probably chemically, and that intrusive granite in tongues 
were forced through the deposits along their bedding planes, the 
whole being afterwards folded into anticlinal and synclinal curves 
by the same terrestrial movements that caused our mountains, 
but chiefly by the lateral pressure of the ocean on our eastern 
coast. A system of strike and dip joints, having approximately 
the same bearings, being seen both in the crystalline schists and 
granites, but especially distinct in the latter, show that both 
classes of rock have been subjected to the same strains; and 
since they have been affected somewhat differently by these 
forces, and show no transition from schists into granite, or vice 
versa, they must have been different in their origin. The regional 
metamorphism, due to intense and continued pressure, has left 
traces in the granite, where the mica frequently shows a tendency 
to arrange itself in lines parallel with the strike. Black mica 
is mostly found in the body of the rock, while the white mica 
oceurs on the joint faces. Bands of hard, dark granite course 
through the country in a more easterly direction than the softer 
granites, and appear to be of a later date. The same earth 
movements, assisted by water, caused the early sediments to 
change their physical and mineral composition. We hear much 
about the heat given off by chemical and mechanical means 
playing an active part in the metamorphism of our rocks. I 
am inclined to think that the value of this agent is much 
exaggerated, for in regional metamorphism, due to pressure, the 
force will be exerted gradually, during which time the rocks will 
both conduct and radiate the heat away. Terrestrial forces are 
being exerted at the present day, and yet we do not notice any 
extraordinary change in the temperature of the rocks; tests 
made to determine the temperature at different depths vary so 
much as to be of no practical universal value. Chemical heat, 
again, we know to be great, but much of our direct knowledge is 
obtained from underground workings, which expose a larger 
surface of oxidisable minerals to the action of the moist atmo 
