The Geology of Hingham. 25 



mentioned. Granite too underlies the whole of the areas named 

 now covered over by the clays, the sands, and the gravels of the 

 glacial period. It also extends north to the shore on Weir River, 

 and to the coast line of the harbor on the eastern shore, where it 

 is found bordering the channel from near the steamboat landing 

 to Martin's Well, and showing itself prominent upon the adjacent 

 uplands. It appears also within the harbor upon the small island 

 known as Button Island. The rock varies in different localities, 

 being sometimes found composed entirely of quartz and ortho- 

 clase,but sometimes with mica added, making it a true micaceous 

 granite. The color varies generally with that of the orthoclase, 

 which is often of a reddish hue. Quartz veins are not infrequent 

 in it, but these rarely furnish crystals ; some, however, of fine 

 amethvstine tint were obtained a few years since from the rock 

 of Old Colony Hill. 



The granite of Hingham is generally too much fissured to afford 

 good blocks for building, though there are locations where, if 

 better situated for cheap transportation of material, stone might 

 be quarried to advantage. Near Long Bridge Lane a quarry was 

 opened and worked for several years by Mr. Israel Whitcomb, 

 and much excellent stone was obtained and made use of for local 

 requirements. 



There are many places where fine red granite is found, but the 

 color is not often persistent over any considerable area, and the 

 stone is not sufficiently free from cracks to admit of good blocks 

 being procured, though possibly these might disappear to some 

 extent at a small distance from the surface. 



The exposures of granite are very numerous. A few that differ 

 from the rest in general character are here mentioned : — 



er 



In Laseil .Street, reddish with epidote. 



In Central Street, red and flesh-colored from the tint of the orthoclase. 



In Union Street, with flesh-colored orthoclase. 



In Thayer Street, red, nearly binary. 



In French Street, flesh-colored, with mica and hornblende. 



In Whiting Street, very fine structure, light-colored and micaceous, 



with very numerous joints. 

 In Summer Street, red, mostly binary. 

 In Emerald Street, red, mostly binary. 

 In Beechwood Street, decomposing. 

 In Thaxter Street, finely porphyritic with red orthoclase crystals. 



Specimens of these may be found in the collection of the 

 Public Library. 



DIORITE. 



Diorite, as mentioned, is found within the region generally 

 occupied by the granite rocks, but it nevertheless may be noticed 

 that in Hingham it is not found far from the sedimentary forma- 



