The Geology of H Ingham 



35 



Weir River. — In the granite rocks of the east side of Weir 

 River, north of Rockland Street, may be seen several dikes. One 

 may be found a few hundred feet below the Riverside House, ex- 

 tending from the river bank in an east-southeast direction, having 

 a width of six feet. There are two others not far distant having 

 the same general direction, each about two feet wide. Still 

 another was noticed of less width than either mentioned, having 

 pieces of granite, through which it had cut, enclosed. 



Beach near Summer Street. — On the beach east of Hersey's 

 wharf, near the steamboat landing and about ninety yards from it, 

 may be seen a trap dike running east and west, having a width of 

 nine feet. This dike has veins of epidotc. 



About twenty-eight yards beyond this there is another east and 

 west dike of the same character, which is somewhat irregular and 

 intermixed with granite, but showing, where distinct, a width of 

 two feet. 



Fifty yards farther a dike is reached which crosses the beach 

 in the granite, and which is particularly interesting, because it 

 shows within its body a continuous mass of granite which was 

 torn from the walls of that rock and enclosed in the igneous ma- 

 terial, when this was irrupted from beneath in a molten condi- 

 tion. See Figure No. 2. 



Figure No. 2. 



One hundred and twenty-five feet farther east a small cove, 

 called Mansfield's Cove, is reached, where may be seen just at its 



