Geoscience Reference
In-Depth Information
MAINE BOASTS
more islands than anywhere else on the Atlantic coast, with 4,617 islands listed in the state's
Coastal Registry. Their granitic foundations were formed by molten rock that bubbled up from deep within the
Earth when the European and North American Plates collided 430 million years ago. Today, the islands them-
selves are formed of drowned ridges, hills, and mountaintops, but most have a low profile, since this coast has
rebounded only relatively recently from glacial pressure. An exception is Mount Desert Island, whose pink
granite heights at Great Head rise 44 meters (145 feet) above the pounding surf. Outer islands are exposed to
the full fury of the infamous nor'easters. On Monhegan Island—the name derived from the Algonquian, “out-
to-sea-island”—such storms send a veil of spray over top of the 30-meter-high (100-foot), spruce-clad White
Head.
Monhegan was an important landfall for early sailors and fishermen. In 1605, the explorer George Wey-
mouth described it as “woody, growen with Firre, Oke, and Beach, as far as we saw along the shore . . . The
water issued forth down the Rocky Cliffs in many places; and much fowle of divers kinds breed upon the shore
and rocks.” Still today, the island shelters a hardy community of winter fishers.
The many islands along Maine's rocky coast “look like so many wood chips scattered across the water,” the
dean of New England natural historians, John Hay, once wrote. This dense scattering of islands has an import-
ant biological effect, boosting productivity along the entire coastline.
As the water of the Gulf of Maine circulates among the islands, they help to mix and oxygenate it, as well as
causing local upwellings that draw the colder, nutrient-rich water from the bottom into the photic zone. The
volume of food available to filter feeders and their predators is also increased as tide-driven currents are
funneled between the islands.
Islands significantly increase the overall length of the Gulf of Maine coast, much of which is clothed in sea-
weeds that serve as the principal primary producers in the inshore environment. Lobsters, crabs, and fishes
make inshore migrations in spring and summer and find shelter in the underwater rockweeds and kelp forests
surrounding many of the islands. This habitat is particularly important in the life cycle of lobsters, when they
abandon their deep water winter grounds and begin to shed their shells. During this vulnerable period, rock-
weeds provide cover and a rich source of food as the lobsters transform themselves from scavengers to filter
feeders.
For these reasons, Maine islands are frequently rimmed by a garland of lobster traps, and in fact the largest
lobster harvests are found along sections of the coast with the largest number of islands.
