Cycles of Wind and Sand

A home on Edgartown’s Katama Bay
gracefully embodies its dynamic surroundings

The shape of Katama Bay, winding between Edgartown and Chappaquiddick, is one of the defining features on a chart or map of Martha’s Vineyard. Depending on one’s perspective, it could resemble a sea lion rising up on its front flippers or the likeness of the hookah-smoking caterpillar from “Alice in Wonderland.” To further complicate the Rorschach Test of this estuary is the fact that its boundaries undergo constant fluctuation and change, and this is only at its surface. On the bay’s floor, beneath its shallow, tidal-driven and wind-frothed water, the sand shifts and rolls in whorls that resemble the cascading petals of giant peonies—the flowers that Marco Polo once described as “roses, big as cabbages.” To view aerial photos documenting the shape of the sandy floor over a span of months and years is akin to returning to a flower garden year after year and studying its patterns, its spiraling calyces and corollas. 

In 2011, the Woods Hole Oceanographic Institution (WHOI) began charting the bottom of Katama Bay using a Sea-Doo jet ski and sonar technology. The project immediately showed benefits for the harbormaster and oyster farmers who had been operating for decades with outdated charts. The U.S. Department of Defense also became interested, as the data could help the Navy to operate in other such inlets around the world. WHOI explains that the sands shift so dramatically because Katama Bay has two inlets. According to the report, “Water pours in from Vineyard Sound through Edgartown Channel, and from the Atlantic Ocean through Katama Inlet. The size of Katama Inlet runs on a 10-15-year cycle, ranging from an opening a few kilometers wide, to a very narrow opening, to completely closed.” This variation in size causes circulation patterns to change, thus altering the underwater landscape. Some years the sand peonies look neat, almost manicured, while other years they seem to explode. In 2007, the Atlantic broke through near Norton Point. The cut then migrated east at a rate of about 500 yards per year until 2014, when only a small outlet existed in the far corner next to Chappaquiddick. In April 2015, the sands made another surge and sealed it off completely, so that it now resembles its appearance in 2006.