UU OOWTRIBUTIOWS TO THE GEOLOGY OF MAINE, [bull.166. 
DOUBTFUL TRACHYTES, 
5] ecimens of a traehytic-looking rock were collected on the South 
Branch of Caribou Stream in Woodland Township. The specimens 
have a fresh appearance and present two varieties. The greater part 
Lease, bluish-gray rock, uniform in color and texture, and easily 
broken into any desired shape, while the other variety differs only in 
the presence of vesicular cavities J to 2 millimeters in diameter, which 
constitute nearly one-third of the whole mass. These two rock types 
are different part- of one lava flow of uncertain size. The cleavage 
cracks and cavities are now tilled with calcite. 
The microscope reveals an advanced state of alteration not suggested 
by the hand specimen, and the minerals can not be determined with 
certainty. The vesicle- are found to be present in the dense variety 
also, differing from the others only in size. They are generally round, 
with a border of tine, fibrous calcite and chlorite alterations, and tilled 
with chlorite or calcite. The ?roundmass, so far as can be read through 
the extensive alteration to carbonates, is of bent or curved orthoclase 
. which are long and narrow, with irregular outline, frayed-out 
edges, and ragged ends. The ferromagnesian minerals have entirely 
disappeared. The groundmass is trachytic in structure, with poorly 
developed flow structure. All that can safely be said of these rocks is 
that they are parts of a vesicular lava flow, probably belonging to the 
trachyte group. 
QUOGGY JOE gUAKTZ-TRACHYTE. 
Macroscopic ascription. — The entire mass of the Quoggy Joe group 
of hills is of this material, and the drift bowlders and widespread 
talus make it a very common fleld rock over a large area. It presents 
various aspects, owing to its state of alteration, but is easily distinguish- 
able from other rocks of the region by its white color when broken 
and by its method of weathering. The freshest material was found 
on the summit of the hill, where it has a whitish-gray or yellowish- 
chocolate color and is very dense and felsitic in appearance. The 
whole mass is cut by cleavage planes, and under the hammer a hand 
specimen breaks into rudely rectangular blocks, indicating numerous 
inconspicuous cleavages or planes of weakness. The fracture is uneven, 
and exposes a rough, trachytic surface with a certain silky sheen. The 
whole rock, weathered and fresh, is spotted with minute black and 
brown dots, which prove to be iron ore and alteration products. 
Besides the planes of fracture spoken of. the rock shows many little 
long and exceedingly narrow cavities arranged in parallel rows, which 
seem to indicate stress insufficient to form complete cracks, but which 
may represent original vesicles drawn out by flow or shearing. These 
