164 -P>'o/. J. B. Dana — Mefaniorphism of 



felspar. On the south side of Montrose Point facing Crnger's Point 

 (or the brick-yard between the two), in the chrysolitic rock, there is 

 what looks like a vein or dyke two to four inches wide, exposed for 

 a length of twenty feet. The material shows it to be no vein or 

 dyke, but a bed from the schist ; it is a dark-coloured quartzose 

 garnet rock, heavy with magnetite and containing some staurolite, 

 resembling much a portion of the schist in section 1 (above de- 

 scribed), near the soda-granite. The covering of earth prevented a 

 determination of its whole extent. In the same kind of rock, about 

 lifty yards north of the brick-yard which divides Montrose Point 

 (into a North Montrose and a South Montrose Point), a vein-like 

 band, two feet to twenty inches wide, descends the bluff, which 

 consists of a light-grey massive argillite. Examined in thin 

 slices by the microscope, it is found to have a mealy aspect with 

 microlithic points, like an argillite in the first stages of metamor- 

 jjliism. The band is a bed from the schist, although a different 

 variety of it from any exposed at Cruger's. 



Other long vein-like bands are black and of very fine grain ; 

 some of them look greyish and minutely arenaceous. The micro- 

 scope shows, on an examination of thin slices, that some consist of 

 grains of hornblende and felspar, the latter partly orthoclase, and 

 look like hornblende schist, while others are very fine-grained 

 hornblendic mica-schist. One of the latter had a thickness of two 

 feet. These bands are most numerous in the norite of the northern 

 part of the point. Figure 4, as stated on page 111, represents an 

 " inclusion " in the norite ; but the inclusion is evidently a bed bent 

 bach on itself; for a vein would not be thus folded double in its 

 enclosing rock. The rock of this bed much resembles the norite, 

 though finer in grain, and consists (as observed by means of a thin 

 slice) of hornblende with much augite and some triclinic felspar. 



On the same part of the point, the norite and chrysolitic rocks 

 apparently cut through one another, but with the norite oftener like 

 an inclusion in the chrysolitic rocks. Again, they follow one 

 another, or lie side by side, but without a distinct divisional plane ; 

 and in one place the rock consists of bands of norite and chrysolitic 

 hornblendite without a trace of any jjlanes of separation. Figure 16 

 represents an example of this kind, 

 in which the bands are two to three 

 inches wide, norite bands (the 

 fine-dotted in the figure) alternat- 

 ing with bands of the chrysolitic 

 rock. Difference of material 

 successive portions might, under 

 some metamorphic conditions, give 

 rise to such a structure, although 

 the bands are so thin ; successive 

 outflowing of different eruptive 

 rocks could not produce it. 



Going north from the vicinity of Cruger's Station along section 1, 

 instead of section 3, the rocks change from the coarse diorite at 



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