78 The Sedimentary, Met amorphic, 



where the line of separation between them and the schists is 

 marked. When, however, one passes into the other, as I 

 shall show later on, at p. 79, it is different. In the cases of 

 which I am now speaking, I believe these apparently isolated 

 masses are connected below with other veins and masses of 

 intrusive kind. Such veins, therefore, as a whole, form a 

 branching network, whose meshes are filled with schists or 

 other rocks. Veins of this kind are clearly intrusive, while 

 the quartz veins have been deposited from solutions probably 

 during metamorphic processes. I give in fig. 1, Plate III., 

 a rough sketch of part of 'this schist-mass, showing the 

 features I have, above spoken of. At 4 there is again a 

 sudden change to crystalline-granular rocks resembling those 

 at 1 to 2, extending to 5, with traces here and there of a 

 schistose structure. 



Similar rocks extend to 6, where there are massive 

 crystalline-granular rocks, with joints dipping S. 45° W. 

 at about 80°. I found this rock to be a noncrystalline 

 compound of felspar, quartz, chlorite, with traces of black 

 mica. The mica is very ragged and worn in appearance, 

 and extensively converted into chlorite, together with 

 colourless epidote granules. It is evidently the first formed 

 of the constituent minerals ; but beyond this all that can be 

 said is that it has the character of the black iron-magnesia 

 micas of the quartz-mica diorites of the district. 



The felspars are next in order of generation, and are of two 

 kinds, one most probably orthoclase, the other triclinic, and 

 of a very compound structure. The quartz, which is the 

 latest in order of formation, is in interlocking grains, filling 

 in and conforming to the interspaces of the other minerals. 

 This rock therefore belongs to the quartz-mica diorites, and 

 is part of the invasive plutonic masses. 



Adjoining this massive rock there is, again, a band of schist 

 similar to those already described. The crystalline-granular 

 rocks again reappear at 7, with two sets of joints, one 

 dipping S. 60° E. at about 80°, the other vertical on 

 a strike of S. 25° W. t Crossing these rocks at 8 is a 

 dyke of micro-porphyritic basalt about 5 to 6 feet in width, 

 dipping S. 15° W. at 70°. 



I found this basalt to have a ground-mass of numerous 

 small triclinic felspar prisms crossing each other in all 

 directions, and thus forming a network, in the meshes of 

 which are numerous grains of yellowish augite, together 

 with crystals of magnetite, either singly or forming character- 



