Most of the Maine coastline is rocky, and erosion isn’t a major problem. But 40% or 1,400 miles of coast have loose or “unconsolidated” rock, clay, sand, or gravel bluffs that slope steeply down to just above the high tide line and are easily eroded.
Bluffs form where the rising sea has encountered piles of sediment left behind by the glaciers during or soon after the last Ice Age. Storms, coastal floods, waves, and tides all work to remove bluff sediments and redistribute them in the coastal zone. Bluff stability varies based on the frequency of waves and storms and whether or not the base of the bluff is protected by a wetland or marsh. Bluffs will continue to erode and move landward due to rising sea levels.