1880 .] 
117 
[Davis. 
The general conclusion which I reach is that the Frenchman’s 
Bay series belongs somewhere between the top and bottom of 
the Cambrian, with the chances in favor of its being near the 
latter. In other words, my observations only tend to corroborate 
the suggestions made by Professor Hitchcock twenty years ago. 
The resemblance of these rocks to the Acadian slates of the Boston 
basin and St. Johns is very marked ; and I join with Professor 
Hitchcock in anticipating the discovery on the Maine coast of char- 
acteristic Primordial fossils. There is something noteworthy in the 
distribution of the Primordial sediments of this part of the world, 
occurring as they do only in arms of the Gulf of Maine, and no 
where far above the present level of the sea; and thus indicating 
that the existing coast-line, at least in its main features, is ol very 
great antiquity and stability. 
Mr. W. M. Davis made a statement of work done on Mt. Desert 
by Messrs. Chas. Eliot, H. A. De Windt and himself during a few 
weeks in the past summer. The range of mountains extending 
E. N. E. across the island was found to consist of a rather coarse 
hornblendic granite ; the limits of this rock on the north were not 
traced, but on the south it was found to be eruptive through a 
diorite, of which it contains many fragments at various places 
along the southern shore. The grain of the granite is distinctly 
finer where the diorite fragments occur than in the range. At 
Bar Harbor, and for some miles along the northeastern coast, a 
series of metamorphosed shales and sandstones dip north or 
northeast under the waters of Frenchman’s Bay: no fossils were 
found in them. 
It would, therefore, seem that the granite of the range is like 
a great dike, several miles in width, breaking through preexistent 
rocks, carrying fragments of the older diorites on the south, and 
probably affecting the position of the stratified rocks on the north : 
part of the height of the mountains is probably due to this 
eruption. 
The inefficiency of the range as a watershed is remarkable. In 
a length of some fourteen miles it contains ten summits averaging 
