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Bridge, going east, and less than a quarter of a mile before 

 reaching the town line, a porphyritic dike 6 feet wide crosses the 

 road diagonally, trending about east-west. On the east side 

 of Lazell Street, 740 feet south of Free Street, the high ledge 

 of granite is cut by a very similar east-west porphyritic dike 6 

 feet wide. About 50 feet south of it is a parallel dike 32 

 inches wide. At the granite quarry on Long Bridge Lane 

 may be seen two east-west dikes about 30 feet apart, one about 

 a foot and the other 22 inches in width. 



On Friend Street, near Main Street, two east-west dikes 

 cut through the granite of the roadway. The first is 330 feet 

 from Main Street, from 4 to 6 feet wide, and has been traced 

 from the road east about 100 feet and west across the meadows 

 about 1,000 feet. The second is about 40 feet beyond the 

 first, 2 feet wide, and has been traced 120 feet or more. In a 

 ledofc of o-ranite on Union Street, about 360 feet from Lazell 

 Street, an east-west dike can be traced about 100 feet. It 

 varies in width from 15 inches to 2 feet, and is quite irregular. 

 About 2,000 feet beyond this, going from Lazell Street, 

 another east-west dike, from 3 to 4 feet wide, crosses the street 

 diagonally, and has been traced 75 feet into the field on the 

 left. 



A dike at least 12 feet in maximum width crosses the junction 

 of Rockland and Summer Streets, on Old Colony Hill, and 

 has been traced east across the adjoining field a total distance 

 of 815 feet. On the east side of the harbor, about 275 feet 

 north of the steamboat landing, is an east-west dike 9 feet 

 wide, with veinlets of epidote. About 80 feet farther north is 

 a more irregular but similar and parallel dike about 2 feet 

 wide. Beyond this, about 150 feet, a third dike encloses a 

 large mass of granite. A fourth dike of the system, (> feet 

 wide, is exposed, 125 feet farther along the shore, at the 

 entrance of Mansfield's Cove. At the north end of Martin's 

 Lane, an east-west dike, 6 feet wide, can be traced 100 feet in 

 the granite ; and in the outcrops of granite about 500 feet in 



