The broad flat areas of sand on the Beach were very susceptible to the whims of the wind. Now and then, as the wind eroded the sand particles from one place, and blew them to another, it piled them up against the base of some beach plant. Collecting here, the sand began to form a gentle slope with a sharp drop-off downwind. Continuation of this action sometimes built up a huge mound, which we call a dune. This process of erosion and deposition still goes on. Usually you can tell the general direction of the prevailing wind by observing which way it builds the gentle slope as it piles the sand into ripples or mounds. If you should mark a dune’s position today and return in several years, you might find that the dune had moved several yards from its original position. Dunes move slowly downwind, such movement being termed “migration.” With a normal dune, during windy periods the sand is blown up its gentle slope and dropped over its crest, whence it slides down the lee side. In this way the dune migrates with the wind. THE FUTURE OF CASTLE NECK Eventually, of course, the dunes might migrate the entire length of the Neck and again be blown into the sea, which would carry the sands farther south, mayhap to become part of Coffin and Wingaersheek Beaches. In fact, we might expect the eventual removal of the entire Neck if sand wasn’t constantly being added from similar erosion going on farther north. Obviously there is a very delicate balance here, adding and subtracting sand. The future of Castle Neck is entirely dependent upon the sand supply from the north. Too little may eventually diminish Crane’s Beach; while an increase could create an even larger and more beautiful Neck. Actually, it is impossible to predict the future of a beach, at the mercy, as it is, of changes in any of the several factors controlling its form—sand supply, waves, currents, and position of sea level. Anyway, what has been so long taking shape will not be altered drastically overnight. As a matter of fact, if you really wish to know the future of Crane’s Beach, you will have to be patient. Another million and a half years will probably tell the story! GEOLOGICAL DISCOVERIES YOU CAN MAKE _Ventifacts_ These small, faceted pebbles found in the dunes have been blasted by the windblown sand. They show the powerful abrasive action of the wind. Most of those you will find here were faceted just after they had been deposited by retreating glacial ice. A migrating dune or a blowout in the sand has left them uncovered. _Erratics_ Large rocks occasionally found in the dunes are called “erratics.” In this world of tiny particles they appear very much out of place, but they were carried here by the glacier a million years ago. They have been uncovered by the migration of some dune. _Fulgurites_