T. S. Hunt rni Oranitic Rocks. 85 



§ 6. Many of the so-called granites of New England are true 

 gneisses, as for example, those quarried in Augusta, Hallowell, 

 Brunswick and many other places in Maine, which are indigen- 

 ous rocks interstratiiied with the micaceous and hornblendic 

 schists of the great White Mountain series. To this class also, 

 judging from lithological characters, belong the so-called granites 

 of Concord and Fitzwilliam, New Hampshire. Tliesc iiidigcn- 

 ous rocks are tenderer, less coherent, and generally finer grained 

 than the eruptive granites, of which we have examples in the 

 micaceous granite of Biddeford, Maine, and the hornblendic 

 granites of Marblehead and Stoneham, Mass., and Newport, 

 Rhode Island ; in all of which localities the contact of the erup- 

 tive mass with the enclosing rock is plainly seen ; as is also the 

 case farther eastward, on the St. Croix and St. John Rivers in 

 New Brunswick, and in the Cobequid Hills and elsewhere in 

 Nova Scotia. The hornblendic granites of Gloucester, Salem 

 and Quincy, Massachusetts, seem also, from their lithological 

 characters, to belong to the class of exotic or true eruptive 

 granites.* The farther discussion of the nature and origin of 

 these gneisses and granites is reserved for another occasion, and 

 we now proceed to notice the history of granitic veins. 



§ 7. The eruptive granitic masses just noticed, not only in- 

 clude fragments of the adjacent rocks, especially near '^- i^"'^ 



very often send off dykes or veins into tl 

 The relation of these with the parent i 



roundii.Q 



however generally obvious, and it may be seen that they do not 

 differ from it except in being often finer grained. These injected 

 or intruded veins are not to be confounded with a third class of 

 granitic aggregates, which I have elsewhere described as granitic 

 veinstones, or, to express their supposed mode of formation, en- 

 dogenous granites. They are to the gneisses and mica-schists, 

 in which they are generally enclosed, what calcite veins are to 

 stratified limestones ; and although long known, and objects of 

 interest from their mineral contents, have generally been con- 

 founded with intrusive granites. 



§ 8. Scheerer, in his famous essay on granitic rocks, which 

 appeared in the Bulletin of the Geological Society of France m 

 1847, (vol. iv, p. 468), conceives the congealing granitic mass 

 to have been impregnated with "a juice," which was nothing 

 else than a highly heated aqueous solution of certain mineral 

 matters. This, under great pressure, oozed out, penetrating even 

 the stratified rocks in contact with the granite, filhng cavities 

 and fissures in the latter, and depositing therein crystals ot 

 quartz and of hornblende, the arrangement of which shows 

 them to have been of successive growth. Neither Scheerer, 



* T. S. Hunt on the Geology of Eastern New England, this Journal for July, 

 ^8t0, p. 88; also Notes on the Geology of the vicinity of Boston, Proc. Boston IS at 



