248 



hut very coarsely amyi^claloldal variety, many of tlic larg'er 

 steam-holes, especially, heing filled with cleavahle calcitc, and 

 others with chlorite. The eruptive rock in contact with the 

 slate, although bearing some resemblance to this melaphyr, is 

 probably a true diabase, or, at least, intrusive in the melaphyr 

 as well as in the slate. The contact, which is exposed for 

 about twelve feet, is somewhat undulating or wavy ; but the 

 plainly marked lamination of the slate is quite closely con- 

 formable with the curving contact, so that where two convex 

 curves meet a very sharp fold of the slate projects a foot or 

 more into the trap. Occasionally, however, the contact breaks 

 across the bedding ; and, although it is a conceivable fault- 

 fracture, it appears best, for the reasons stated, to regard the 

 strike-fault between the slate and melaphyr as followed, in this 

 instance, by a dike younger than either but lithologically 

 somewhat similar to the melaphyr. 



On attempting to follow the slate northward along this 

 contact we encounter an undoubted transverse fault, for we 

 pass at once to melaphyr, and the contact is shifted abruptly 

 to the westward or toward the outer edge of the beach about 40 

 feet, equal to a vertical slip of nearly 60 feet, with the down- 

 throw, evidently, to the south. North of the displacement the 

 contact-dike appears to be wanting ; and the slate and melaphyr 

 are seen in actual contact. The exposure, however, is unsatis- 

 factory ; and the evidence is still inconclusive as to the true 

 relations of these two rocks. The displacement is proved 

 also by the conglomerate layers in the slate, previously 

 mentioned ; for these reappear, essentially unchanged, on the 

 point at the end of the beach. The westerly dip of the slate 

 is very constant, being 55° on this part of the shore. 



About 120 feet north of this beach and the small quarry, 

 the transverse fault is repeated in the reverse direction, the 

 two displacements being approximately compensating. The 

 contact between the slate and melaphyr, unchanged in direction, 

 is now in the woods from 130 to 170 feet back from the shore ; 



