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siderable distance. Placed longitudinally in this dike, westward of 

 its middle part, there is a greenstone dike about four feet wide, 

 running out with it seaward to the low point where the porphyry- 

 dips into the water; it is also crossed diagonally by a greenstone 

 dike, which bifurcates upon it, and is seen far up on the hill-side 

 above. Alongside the dike there is a pretty large cave. The 

 pitchstone and other dikes traverse the sandstone platform to the 

 north of this. The principal dike, traceable continuously for a 

 long distance, is formed of green pitchstone; it rises from the sea 

 southward with a range 40 E. of N., a width of ten or twelve feet, 

 and a S.E. inclination of nearly 30; but the course undulates 35 

 or 45, bending towards the west, or into parallelism with the shore, 

 towards its northern termination. There are veins of slaty horn- 

 stone on both sides, next the sandstone, and on one side a thin layer 

 of basalt. On the side of the great vein next the sea, numerous 

 veins enter it nearly at right angles. First, a vein of hornstone 

 six to eight inches wide ; next, one of basalt five feet wide. Another 

 vein running a little N. of W. has on its north side three 

 feet of pitchstone, passing into hornstone, then four to six inches 

 of clay stone, and on the south side fifteen feet of basalt or 

 fine greenstone. Next is one thirty feet wide running 35 W. 

 of N., consisting of basalt four feet; claystone fifteen feet; basalt 

 again six feet, containing a pitchstone vein along its middle part ; 

 lastly, a vein of greenstone five feet wide. There is here also 

 a vein of trap porphyry four feet wide: this and the others 

 intersect the pitchstone vein, but the intersection is obscured 

 by debris. The last vein northwards, is one of pitchstone with 

 hornstone and jaspery quartzite, running oblique to the shore, and 

 varying from eleven or twelve to thirty feet. Just outside the 

 tideway it meets and enters the great pitchstone vein, which, in its 

 sweep north, has reached this point, ranging now 10 E. of N., 

 and at the junction there is nothing visible but claystone, which 

 forms the flooring at the common point of union. The great 

 vein stops here ; but that we are now noticing continues its course 

 under masses of sandstone, but is not seen in the cliff aloft, nor can 

 it exist there. Still farther north we noticed a pitchstone vein 

 running E.N.E., seven to ten feet wide, and visible in the cliff 

 above; but apparently in no way connected with the other veins. 

 The close association of so many igneous rocks is extremely 

 curious; we can hardly suppose the various products to be other 

 than cotemporaneous ; so that different rates of cooling and varying 

 chemical composition must have produced the differences now 



