AGENCY OF THE SEA. 145 
tinuation of those occurring on the main land, the 
most cautious reasoner can hardly avoid the con- 
clusion that such was the origin of this harbour. 
Nay, it is difficult to see why the same reasoning 
will not apply to the whole of Massachusetts Bay ; 
and when we see with what tremendous force the 
ocean must, for ages, have battered the hard syenitic 
rocks of Cape Ann, and what an immense accumu- 
lation of sand, gravel, and bowlders has been made 
along the south shore of this bay, we feel almost 
prepared to adopt this theory," &c. 
Lieutenant Mather, geologist to the first district 
of the State of New- York, thus speaks of the en- 
croachments of the sea upon the shores of Long 
Island : 
Vast masses of the cliffs of loam, sand, gravel, 
and loose rocks, of which Long Island is compo- 
sed, are undermined and washed away by every 
storm. The water on the ocean coast, to some dis- 
^tance from the shore, is almost always found to 
have more or less earthy matter in suspension, 
much of which, except during storms, is derived 
from the grinding up of the pebbles, gravel, and 
sand, by the action of the surf. This earthy matter 
is carried off during the flood tide, and in part de- 
posited in the marshes and bays, and the remainder 
is transported seaward during the ebb, and deposited 
in still water. After a close observation, I have es- 
timated that at least 1000 tons of matter is thus 
transported daily from the coast of Long Island, and 
probably that quantity, on an average, is daily re- 
moved from the south coast, between Montauk 
Point and Nepeaque Beach. This shore of 15 miles 
in length probably averages 60 feet in height, and 
is rapidly washing away. 1000 tons of this earth 
would be equal to about one square rod of ground, 
with a depth of 60 feet. Allowing this estimate to 
be within the proper limits, more than two acres 
would be removed annually from this portion of 
