Review of Recent Geological Literature. 217 
The succession for the acid volcanics is tuffs, taxitic aporhyolites, 
spherulitic aporhyolites, flow breccias and tuffs. The author deems 
that the eruption began before that of the Thoroughfare volcanics had 
concluded, and was from a different though neighboring vent. 
In addition to the formations already described, there are great intru- 
sive masses of granites and diabases, besides numerous dykes of quartz- 
porphyry and diabase. These intrusive, holo-crystalline rocks consti- 
tute the larger part of Vinal Haven. The ease with which the granite 
can be quarried and worked, the fine polish which it takes, and the 
proximity of the quarries to good harbors have rendered this rock of 
very considerable economic importance. The Vinal Haven quarries are 
said to be the most extensive in operati<m in America. Petrographically 
the rock is a typical biotite-granite with porphyritic facies. It is free 
from basic segregations, but contains numerous aplitic veins, which 
are considered by the author igneous injections subsequent to the con- 
solidation of the granite. Associated with this true granite is a ''black 
granite'' which proves to be olivinc-diaba.se and diorite. These basic 
intrusives are older than the granite which cuts the dialjase in numer- 
ous sheets and dykes. The quartz-porphyry and diabase dykes are 
doubtless connected genetically with. the corresponding acid and basic 
massive intrusives. 
The time of the intrusion is conjectural. The dyke relations show the 
intrusives to be younger than the formations previously discussed. 
The plutonic conditions of the granitic crystallization necessitate 
a cover which has subsequently been removed. Time must also be al- 
lowed for the diabasic intrusion with its thinner cover. Hence a con- 
siderable interval must separate these intrusives from Niagara time. 
The alteration which the igneous rocks have undergone has been due 
to the action of both superficial and deep-seated forces, and is both 
structural and mineralogical. The former is seen only in^ the change of 
diabases to greenstone schists. The latter alteration is by far the more 
universal and important and is considered by the author to be more of 
the nature of weathering than true metamorphism. The results of this 
alteration may be covered by the processes of saussuritizatiou, epi- 
dotization and chloritization. 
It is questionable whether saussuritizatiou (s3e Rosenbusch, Mikros. 
Physiog., .3rd ed., vol. ii. p. 282) can be considered a process of weath- 
ering rather than of metamorphipm. Undoubtedly dynamic metamor- 
jjhism is not essential to this process, but may not a static metamor- 
phism be distinguished from those processes of disintegration (weather- 
ing) whereby, by means of hydration or carbonatization. compounds less 
crystalline and more soluble than the original comjDOunds are produced? 
Devitrification is a good example of a similar metamorphism where, as 
the author points out, dynamic action is not needed as an initiatory 
factor in the process. 
Noiiienclatare. Under this caption the question of the terminology 
of the volcanics is discussed. (1) The acid volcanics are termed apo- 
rhyolites on the ground of being devitrified rhyolites. (2) The more basic 
