THE 
AMERICAN GEOLOGIST. 
Vol. XXVI. DECEMBER, 1900. No. 6 
NOTES ON THE GEOLOGY AND PETROGRAPHY 
OF MONHEGAN ISLAND, MAINE.* 
By E. C. E. Lord, Washington, D. C. 
Plate XXIII. 
Monhegan is the most important member of a small group 
of islands, situated within the depressed coastal area of Maine, 
about 10 miles to the south of Saint George peninsula and 12^2 
miles almost due east of Book Bay harbor. 
The group may be considered geologically as a dissected 
plutonic mass forming a part of the Acadian province out- 
lined by professor Danat in his publications on the Archaean 
axis of North America. 
The orographic movements resulting in the submergence 
and re-elevation of the Maine coast have been carefully record- 
ed by Prof. Shaler in his study of the geology of Mount 
Desert,^ and some of his observations may be duplicated, on 
a smaller scale, in tracing the geologic history of Monhegan. 
Thus we find, at various elevations marine benches and water 
worn caves marking periodic changes of sea-level. It seems 
improbable, however, judging from the present work of the 
*The writer wishes to acknowledge his indebtedness to the author- 
ities of the United States National Museum for kindly allowing him 
the opportunity to work up the material. He is especially indebted to 
Prof. Geo. P. Merrill, head curator, Dept. of Geology in the Museum 
for the privilege of studying the collections, and to Mr. Geo. C. Cur- 
tis, of Cambridge, Mass., for valuable suggestions concerning the 
physiography of the island. 
fBuU. Geol. Soc. Amer., Vol. 7, p. 36 and Amcr. Jour. Sci. (3rd 
series). Vol. 39, p. 378. 
J8th Annual Rep't U. S. G. S., 1887, p. 993. 
