OF DYNAMICAL GEOLOGY BAILEY. 193 



vicinity a mass of granite, 20 or 30 feet wide, may be seen 

 enclosed between tilted beds of quartzite and running for 100 

 yards or more in perfect conformity with the latter, then suddenly 

 terminating. On the other hand on the Shelburne River, where 

 crossed by the post road, may be seen a good illustration of the 

 intricate blending of the granitic and schistose masses commonly 

 met with along their lines of contact. Regularly stratified beds 

 are, as before, abruptly cut off across their line of strike, long 

 irregular tongues of granite invade the associated strata, and 

 what look like detached blocks of the latter are sometimes com- 

 pletely enclosed by granite. 



In the section on the Nictau River, already referred to, and 

 just north of Alpina Station, is a good opportunity of studying 

 the intrusion of granitic masses among Devonian strata, showing 

 both the exotic origin of the granite and the period of its 

 extrusion. 



In connection with the granitic masses, both small and large, 

 occur numerous veins in which the constituent minerals of 

 granite, viz., quartz, felspar and mica, have been segregated out 

 on a larger scale, affording fair specimens of each. A good 

 illustration of such segregated veins may be seen at the western 

 head of Liverpool Harbor, at the Government Breakwater, where, 

 in addition to good specimens of felspar, may be found sheafs of 

 pale yellowish plumose mica. In some instances these veins 

 carry tourmaline and garnet as well as mica. 



Still a third type of veins, abundantly illustrated in the 

 region under review, is found in connection with the traps of 

 Digby Neck. Like the veins in the Cambrian rocks, first 

 described, these are usually silicious, but whereas the former are 

 of pure milky quartz, with accompaniments of metallic sulphurets 

 and gold, the latter are as generally highly colored and banded, 

 including all varieties of agate, jasper, chalcedony, &c., as well 

 as amethyst, while the associated minerals are calcite, zeolites of 

 many varieties, together with oxides of iron (hematite, martite, 

 magnetite). Simple veins of agate and jasper, from one quarter 

 of an inch to a foot in diameter, may be seen almost anywhere 



