312 The American Geologist. aed Ris 
description of the microscopic characters of the rock specimens studied. 
All the essential features of the original paper are retained in the new 
edition, but some of its more technical features have been omitted. 
The Fox islands comprise a group of rocky islands in Penobscot 
bay. They are composed largely of greenstone-schists, volcanic lava 
and various intrusives. Subordinate areas are occupied by sedimen- 
tary rocks. The greenstone schists are basic lavas and tuffs of Pre- 
Niagara age. The sediments are in two small areas, one in Vinal 
Haven and one in North Haven, the two largest islands of the group. 
The North Haven beds comprise 600 ft. of shales, quartzytes, limestone 
and conglomerates that have been determined as Niagara by Beecher. 
The sediments in Vinal Haven are quartzytes, quartzitic slates and 
various banded schists, the exact age of which has not been deter- 
mined, but because of their strong metamorphism they are inferred to 
be much older than the Niagara sediments and the volcanic deposits. 
The most interesting series represented in the district are those 
consisting of the lavas and associated tuffs. Of these there are two— 
a more basic series distributed on the shores of the “thoroughfare” 
separating North Haven from Vinal Haven and on the islands in the 
“thoroughfare,” and an acid series confined to-the northwestern portion 
of Vinal Haven. In composition the rocks of the first series are clas- 
sified as andesytes, diabase-porphyries and quartz-porphyries. They 
have suffered much change in the way of devitrification, but their 
structure is well enough preserved to serve as a means for their iden- 
tification. The clastic volcanics are especially well preserved. Their 
tuffaceous structure is particulary characteristic, the typical “‘ash 
structure” being observed in many sections. The acid volcanics of 
Vinal Haven are glassy rhyolytes with beautiful flow structures, 
spherulitic rhyolytes, rhyolitic flow breccias and rhyolitic tuffs. The 
spherulitic phases form striking rock ledges—the spherulites possessing 
all shapes and sizes up to three inches in diameter. 
The volcanic rocks are cut by numerous dykes some of which are 
microgranites or porphyries, but the greater number are diabases 
and quartz diabases. 
The greater part of Vinal Haven—all that part lying south of the 
volcanic rocks—is composed of the famous pinkish gray granite, so well 
known as a favorite monumental rock, and a coarse grained black rock 
which has long been quarried under the name of a “black granite,” 
and which in some instances is dioryte and in other cases an olivine 
diabase. The granite is older than the basic intrusive and both ap- 
pear to be younger than the volcanics. 
Brief descriptions of all the principal types of rocks are given in 
the study and data which served to determine their sequence are 
described. A concluding chapter summarizes the result reached by 
the author and a well executed map depicts the distribution of the 
rock formations. 
The report gives indubitable proof that there was an old volcano 
in the Fox islands region during early Paleozoic time and that it must 
