The other night, I started reading the book "A Dune Adrift: the strange origins and curious history of Sable Island" by Marq De Villiers and Sheila Hirtle. An amazing book that explores the history, folklore, geography, geology and biology of this small cresent shaped island balanced on the edge of the continental shelf off the coast of Nova Scotia.
There are many reasons why Sable Island is such fodder for the imagination. The two reasons it is most well known for are 1/ its wild horses (brought there by mariners in the 1750s), and 2/ it is notorious for being the graveyard of the Atlantic as ships have become stranded and shipwrecked since the 1500s on the shallow bars that extend far from each end of the isle. But, what I'm discovering in reading this book is a greater understanding of the forces that shape the physical profile of this island: "a beach in the middle of nowhere attached to nothing and apropos of nothing, a beach attached to nothing but beach". "Sable is probably kept in place by the currents. But its mass still depends on the winds".
The island is completely made up of sedimentary sand with no bedrock. The sand dunes are very vulnerable and what hold them (somewhat) in place is the vegetaion of maram grass and other bushes. A single wind storm can drastically re-shape the terrain. And because of a combination of ocean currents and winds, the island is moving further and further eastwards, and may one day be pitched over the edge of the continental shelf.