190 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
by erosion. The molten rock from the earth’s interior, though 
penetrating the crust, may fail to reach the surface, and subse- 
quently be revealed by the removal of the surrounding beds, or 
this may come up along a narrow vent, forming a pipe or 
chimney, and, without forming a crater, overflow the region in 
its neighborhood. On the other hand the fact of the igneous 
origin of Curries Mountain is placed beyond question (i) by the 
study of its rocks as regards their nature and arrangement ; and 
(2) by the relations of these to the other rocks with which they 
are associated. 
Volcanic Rocks.' — The rocks which constitute the main mass 
of Curries Mountain are of a dark grey, almost black colour, quite 
hard, of uniform texture and breaking with a broad conchoidal 
fracture. Fresh surfaces glisten somewhat from the presence 
of minute crystals, and on the northwestern face of the hill are 
ledges showing a distinctly columnar structure, similar to that 
of Blomidoin or the Giant’s Causeway. Technically the rock is 
Diabase, a variety of “ trap ” consisting of an intimate admixture 
of felspar (labradorite or anorthite) and augite or pyroxene. 
To the latter, an iron-bearing mineral, the colour, hardness, 
toughness and weight of the rocks are due. It is an admirable 
material for road making, and considerable quantities of some- 
what similar but inferior rock, derived from the outskirts of the 
hill or from boulders, have been used in macadamizing the 
streets of Fredericton, the main mass of the mountain, owing to 
the cost of removal, remaining still untouched. 
No other rock than that last referred to is visible iin the 
mountain itself ; but along the crests of the hills which, as 
already stated, lie in the rear, and extend for several miles in 
the direction of Rockland, are numerous exposures of beds of 
related origin. These are of lighter colour than the diabase 
described above and are earthy rather than crystalline, though 
not unfrequently containing crystalline minerals. These latter 
are usually scattered through the rock in the form of blebs or 
nodules, and include quartz, calcite, heulandite and a variety of 
chlorite known as delessite. Thus the rock is a .sort of volcanic 
