Dunes and Buggies
Cape Cod sand dunes have been made famous in songs, in photographs, and in paintings. The dunes in Wellfleet and Truro rise up to 150 feet high; the ones at Nauset Beach are low and rolling.
There are three elements along the ocean shore, the beach, the sea cliffs, and the dunes. The sea cliffs were formed during glaciation and for some time after. As the sea rose from retreating glaciers, it was wave action that moved the glacial deposits inland to form the sea cliffs. Waves and currents redeposit this material and beaches are formed.
Dunes, on the other hand, are created by wind. Strong winds pick up the dry beach sand and blow it around. When the wind bearing its load of sand hits any obstruction, it slows down and swirls around the obstruction. Slow wind cannot carry the sand, so the sand is dropped in the lee of the obstruction. When the pile is big enough to be an obstruction on its own, more sand is dropped, and a dune is formed. The dune has a steep side leeward, and a sloping side facing the wind. The wind continues to carry sand up the dune and deposits it at the top. Eventually, the dune becomes unstable and some sand slides down again, reshaping the dune. The sand forming the dune is whiter than the beach sand, since the finer sand is picked up more easily, leaving the rougher grains behind.
Dunes are fragile creations. Vegetation helps stabilize them. Beach grass is the most common plant to thrive on the dunes. You might also see Dusty Miller, Sea Rocket, Beach Heather, and Beach Plum.
Oh, and the buggies. Few animals inhabit the dunes. The insects you may notice are the Dune Grasshopper, the Wolf Spider, some flies and wasps.
Nature is amazing!