TOPOGRAPHY. 
The rocky areas or ledges of Cohasset and Nantasket are 
characterized, considering their diversified geologic structure, 
by aremarkable uniformity of elevation, indicating that in pre- 
glacial times this region was worn down nearly if not quite to 
its base-level ; and the deeply incised and generally abrupt 
character of the valleys now dividing this old peneplain shows 
that it must have shared in the general and marked elevation of 
the land at the dawn of the great ice age; while the fact that 
the deeper valleys are now to a large extent occupied by the sea 
or its deposits, 7. e., are or have been true fiords, is sufficient evi- 
dence of a subsequent subsidence ; and, finally, the extensive 
beach and marsh formations prove that the present level of 
the land has been maintained for a very long time. The mod- 
ern base-level is strongly accentuated, not alone through the 
constructive action of the sea, but marine erosion has made ex- 
tensive inroads upon the drumlins and other drift deposits, 
especially of the Nantasket peninsula and adjacent islands, de- 
veloping the prominent sea-eliffs of Telegraph Hill, Point Aller- 
ton, Strawberry and Green Hills, etc.,as well as broad submarine 
platforms or shoals, the outlines of which сап be traced on the 
Coast Survey chart. 
Since even the most typical peneplain must slope gently sea- 
ward, the average elevation of the rock-surface of eastern Mass- 
achusetts increases gradually as it recedes from the coast ; and 
Nantasket and Cohasset are, therefore, one of the lower portions 
of it. In the valleys, the rock-contours are, of course, carried 
down to and below sea-level; but the ledges and rocky hills 
Separating the depressions, the real remnants of the ancient 
peneplain, are, even in the Nantasket area and alone the Co- 
hasset shore, rarely below 50, and usually from 75 to 100 feet, 
in height; and the elevation, increasing very slightly inland, 
attains its maximum of 125 to, possibly, 150 feet in the broad 
