330 Tlic American Geologist. December, 1900 
waves, which is silnply that of cutting back the salients, and 
slightly modifying the re-entrant features of the coast, that the 
topography of the island is to any great extent, the result 
of marme erosion. 
Monhegan Island is of rectangular shape, measuring about 
i^ miles in length, by 3-5 of a mile in width. The smaller 
members of the group (Ma nana. Duck Rock, etc.) lie to the 
west of Monhegan and have with it a N. E.-S. W. trend, cor- 
responding with that of the continental coast-line. 
The topography of the group, as seen by the accompany- 
ing geologic map* is clearly that of a highly glaciated region 
but slightly modified by marine encroachment. 
A very striking feature and one not hitherto noted on other 
islands in this vicinity, is the bold relief of the eastern head- 
lands which rise almost perpendicularly to a hight of more 
than 150 feet above sea-level, thus producing coastal features 
of great scenic beauty and grandeur. These elevations with 
their broad and rounded summits and gentle slopes landward, 
extend in an E-W direction, across the island, broadening out 
and gradually falling away to the western coast-line. They are 
separated by low, broad valleys, or by irregular, basin-shaped 
depressions in which surface waters collect to form small 
ponds and marshes. 
It is of interest to note that these valleys are almost at right 
angles to the direction of the ice-flow, which, as imperfectly 
indicated by glacial groves and markings is but a few degrees 
east of north. This main ice-movement has resulted in the 
excavation of the channel separating Ma nana island from 
Monhegan, as well as of the minor longitudinal gorges so 
common on the island. No direct evidence of glaciation was 
observed in the broad transverse depressions, owing to the 
abundance of vegetation, but it seems probable, judging by 
their peculiar form and the occurrence of erratic bowlders in 
them, that they were produced by ice-currents moving in an 
easterly direction across the island, along lines of structural 
weakness in the underlying rock. 
Since the withdrawal of the ice-sheet marine erosion has 
*This map is based upon a reproduction from an enlarged and 
corrected copy of sheet No. 312 of the U. S. Coast and Geodetic Sur- 
vey prepared by Mr. Geo. C. Curtis, of Cambridge. Mass.. and kindly 
placed at the disposal of the author. 
