Maine’s coastline is made up of diverse geologic landscapes that were created by glaciers during and after the last Ice Age. Maine’s coastal landscape is also influenced by the tide, which ranges from about eight feet in southern Maine to over 18 feet along the Downeast coast.
The majority of the shoreline (58% or about 2,000 miles) is Maine’s characteristic cliffed rocky coast (what geologists call “consolidated bluffs”). However, about 40% or 1,400 miles are soft, loose (“unconsolidated”) bluffs that are vulnerable to erosion. Sand beaches make up only about 2% or 70 miles of the Maine coast, mostly in the southern part of the state.
Learn more about these coastal shoreline types and their associated hazards:
Geologists have classified the Maine coast into four major compartments. Each of these different shoreline types have different characteristics, and each their own inherent hazards.
Southwest Arcuate Embayments
Sandy beaches and salt marshes are most common from the New Hampshire border to Cape Elizabeth, where a sandy bays are separated by a series of rocky headlands.
South-Central Indented Shoreline
In Midcoast Maine from Casco Bay to Port Clyde, long, rocky peninsulas alternate with relatively deep but narrow estuaries that drain bedrock valleys.
North Central Island-Bay Coast
From Penobscot Bay to Cutler, numerous granite islands shelter broad embayments with mud and mixed mud-gravel flats in the intertidal zone.
Northeast Cliffed Coast
From Cutler to Cobscook Bay, a steep, straight bedrock coast is scoured by 20-foot tides and floored with extensive tidal flats.