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South-east of the hght-house, well jutted into the sea, occurs 

 a ledge of the second form of deposit. The third form of 

 deposit occurs in slabs of exquisitel}^ handed or watered 

 Porphyry, which, with a thickness not usually exceeding two 

 or three inches, overlay each other, forming a bed which 

 makes an angle of about 30° with the horizon. Probably 

 the finest specimen of this structure is the bed that outcrops 

 along the shore, a few rods south-east of the wharf of Eph- 

 raim Brown, Esq., on the harbor side of the Neck. Beauti- 

 ful pebbles of the banded Porphyry may be found on the sea- 

 beaches of the Neck. The ledge is well worthy the attention 

 of those wealthy amateurs, whose tastes, sustained by ample 

 means, look across the water to the ornamental stones of 

 Europe for decorations to their dwellings. A mantlepiece, 

 made of banded Porphyry, would be unique and would draw 

 more attention than all verd antique in Boston, and for 

 aught we know as yet, its inherent beauty would sustain the 

 curiosity, that the rarity had awakened. 



When will the man of wealth and taste appear, who, stand- 

 ing head and shoulders above the crowd of weak imitators, 

 will exhibit to, admiring friends instead of the foreign marble, 

 tables of mosaic made from the Serpentine of Newburyport, 

 the marbles of the western sections of the State, the Tour- 

 maline rock of Chesterfield, the Beryls of Royalston, the Por- 

 phyry of Marblehead and Lynn, and the various ornamental 

 rocks which occur in his native State ? 



Passing from the town proper to the adjacent islands, we 

 find the rock in state to be of the same character as on the 

 mainland. The small, almost perpendicular rock that forms 

 a conspicuous mark far out at sea three miles from the near- 

 est land, known as " Halfway" rock, is of the hardest and 

 jDurest Porphyry of a rich purple hue. I am told by our 

 fishermen that a shoal is distinctly traceable from the main- 

 land on the neck to the island, indicating a simultaneous 

 origin. Occasionally in the midst of the Greenstone a 

 jagged, out-cropping ledge of pure quartz protrudes, of a 

 i3rownish-red color, from the presence of a small percentage 

 of iron. An example of this may be found at the left of 

 " Oakum Bay", on the road to fort Sewall. 



It will be seen from the above that the primitive rocks 

 abound in Marblehead ; they present themselves with the 

 characteristics peculiar to them, they stretch along a shore 



