"The Mount" was once an island but is now connected to the mainland by a narrow neck of dune sand (a tombolo) covered with high-rise apartments, shops, restaurants and houses.
A tombolo forms when a beach or sand spit joins up with an offshore island.
Those little islands in Boston Harbor are ice-age remnants called drumlins, some of them connected by sand spits called tombolos.
There are two scoria cones, Macey Cone and Red Island, the latter joined by a tombolo to Laurens Peninsula.
