1880 .] 
109 
[Crosby. 
General Meeting. December 15, 1880. 
The President, Mr. S. H. Scudder, in the chair. Forty-seven 
persons present. 
The following papers were read : 
GEOLOGY OF FRENCHMAN’S BAY, MAINE. 
BY W. O. CROSBY. 
Frenchman’s Bay is a well defined though shallow body of water 
indenting the coast of Maine in a north-north-west direction and 
lying between the main land of Sullivan and Gouldsborough on 
the east and Mount Desert Island on the west. The length of the 
bay, measured from its mouth to Sullivan Falls, is fourteen 
miles, and its average breadth is about five miles. Two 
prominent peninsulas, Crabtree’s Neck and Wankeag Neck, 
project into the bay from the north ; and from the southern end 
of the latter, which lies nearest the eastern shore, a semi-circular 
belt of about fifteen islands stretches first in a south-east direction 
to the Gouldsborough shore, and then directly across the bay 
south-westerly to Bar Harbor on Mount Desert. 
The geology of the region adjacent to Frenchman’s Bay pre- 
sents a strong general resemblance to that of eastern Massachu- 
setts. Except on the islands, and in the immediate vicinity of the 
shore of the bay itself, the rocks are all ancient crystallines, includ- 
ing both stratified and eruptive varieties, which may be classified 
as follows : — 
1. Stratified rock, — mica schist, quartzite, etc. 
2. Eruptive diorite. These basic eruptives are sometimes, 
probably, augitic, and should then be classed as diabase. 
3. Granite. 
The stratified group has its best development in Sullivan, Han- 
cock, and Trenton, i. e ., about the northern end of the bay. The 
prevailing strike in Sullivan is N. W. — S. E., with a variable north- 
east to vertical dip, while elsewhere a N. E. — S. W. strike is 
common ; and, generally, we observe an entire want of conformity 
