SCIENTIFIC SURVEY. 



233 



being vertical. The strata of gneiss are wonderfully convoluted, 

 and very fine specimens to illustrate them in Cabinets might be 

 obtained here. A few layers of hornblende schist of a handsome 

 variety are interstratified with the gneiss. The strata have an 

 average dip of 40° south-easterly, and thus we have the evidence of 

 an anticlinal axis running through this patch of gneiss in the south 

 part of St. George. Curious veins of syenite abound in the trap near 

 the Light House, the syenite appearing conglomerated. It is very 

 rare elsewhere to find syenitic veins in trap rock. The trap dikes 

 are only a few feet wide, and the syenitic veins as many inches. 



In the south part of Gushing we regard the mica schist as pre- 

 dominating, insomuch that upon the large map of the Sate it is not 

 embraced in the same formation with the gneiss of this region. 

 The texture of the rock is very fine and the strata very thin, as if 

 coinciding with planes of cleavage, and the rock altered from clay 

 slate. Veins of granite are remark abl}' abundant, and many of 

 them are very tortuous. Most of the granite in the veins is very 

 coarse-grained. Fig. 34 represents a portion of a tortuous granite 

 vein from this vicinity, the block being twenty-six inches long, 

 and the vein varies from half to three-quarters of an inch in width. 

 The straight lines represent the strata of schist, and the crooked 

 ones the vein. The strata appear not to have been at all affected 



Fig. 34, 



Granite veins in mica schist. 



by the protrusion of the granite. It is difficult to conceive how 

 such a crooked fissure could have been formed at the outset ; and 

 then to imagine how the crevice was filled so compactly and ap- 

 parently quietly. The whole vein as measured is thirty feet long, 

 and it divides into branches, tapering finally to a point. It is 

 wonderful how numerous these contorted veins are at the extreme 

 south point of the promontory. 



Much of the mica schist in Cushing is rapidly decomposing. 

 The dip of the strata varies from 1b° to 80° south-east. At the 

 end of the promontory we noticed an interesting band of conglom- 

 erate twenty feet wide. The cement is mica schist, while most of 

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