Barrier islands are traditionally ephemeral places. Little more than towers of sand piled high in the ocean, these islands, which are often long and narrow, are constantly shaped and reshaped by battering waves and whipping winds. Near-constant erosion and deposition means barrier islands have a tendency to crawl across the ocean<\/a> like dunes in the desert. While Sable Island is farther from shore than a true barrier island, it\u2019s thought to be a remnant of one that formed in the last Ice Age\u2014and it\u2019s subjected to many of the same erosional processes. Transience is such a big part of barrier island dynamics that Byrne\u2019s discovery that some of Sable Island\u2019s dunes have scarcely changed in nearly 30 years has scientists puzzled.<\/p>\n Understanding what makes Sable Island so different from other barrier islands could yield important clues that may help protect against coastal erosion elsewhere. But to figure that out, scientists need to move quickly. In just the past few years<\/a> the Government of Canada has started to let tourists explore the sandy island, which is home to a population of wild horses<\/a>. There is a concern, says Byrne, that all of these extra trampling feet may finally force Sable Island\u2019s unusual dunes to shift.<\/p>\n Sable Island isn\u2019t completely unchanging. The eastern spit of the island, for example, grew five kilometers since 1996, but the sea has since reclaimed most of the new length. Yet according to Byrne\u2019s analysis, presented at a scientific conference in Montreal in May, some of the island, and its dunes, were right where she had observed them 28 years before.<\/p>\n Four of her initial surveys are almost identical to the new data, Byrne explains. \u201cThe heights of the dunes are the same, and the distribution of the peaks and valleys of the dune system across the island is very similar.\u201d<\/p>\n The island\u2019s recent stability isn\u2019t just a fluke. In 1992, David Gray<\/a>, a geodesist, compared six surveys taken over 200 years<\/a> and found that while the tips of the island have changed shape, the island itself hasn\u2019t moved much. This is in contrast to the other barrier islands along North America\u2019s Eastern Seaboard. From New York\u2019s Fire Island<\/a> to Cape Cod<\/a>, residents are being forced to face the reality of the transitory nature of barrier islands as lapping waves wash away their lands.<\/p>\n Sable Island is a barren place. Its name comes from the French word for sand, and unlike the million-dollar homes on Fire Island, that\u2019s pretty much all that\u2019s there now. Small freshwater ponds sustain the island\u2019s wildlife, including the famous Sable Island horses.\u00a0<\/em>Loose wisps of vegetation give the horses something to eat\u2014grasses that also help keep the sand in place. But according to Byrne, some of the dunes have no vegetation at all and nothing really anchoring them. Their relative constancy is a mystery.<\/p>\n Sable Island\u2019s horses are thought to be the descendants of those\u00a0confiscated from the Acadians expelled from the mainland during Le Grand Derangement<\/a>. Photo by\u00a0Pierre Perrin\/Zoko\/Sygma\/Corbis<\/p><\/div>\n The past 30 years have been kind to Sable Island\u2019s geography, but the next few decades may bring new challenges.<\/p>\n![](\"\/wp-content\/uploads\/aabj_horses.jpg\")
<\/a>