Tombolo is an Italian name—accent on the tom—derived from the Latin for burial mound. A tombolo is a pile of sediment that, unlike any other formation on a beach, leads straight offshore from the mainland to an island (or sometimes from one island to another).
Perhaps the most famous tombolo is the one that connects Mont St. Michel to the French mainland. (See it in the photo gallery of this article.) Until a causeway was built upon it, crossing to the island and its ancient monastery was a perilous journey because the 14-meter tides can move in swiftly upon a pedestrian. Across the English Channel, a very similar tombolo connects St. Michael's Mount to the coast of Cornwall. And a particularly large one, Chesil Beach, leads from Britain to the Isle of Portland.
Scotland has its share, too. One of them is in the photo gallery. And my favorite tombolo on the Web has got to be the one in the Shetland Islands in eastern Scotland, connecting St. Ninian's Isle to the larger Isle of Mainland.
You may be thinking that an island connected to the mainland isn't truly an island, just a peninsula of some sort. And indeed, the French have a name, presqu'île, almost-island, for that. There's a tombolo involved at Presqu'Île Provincial Park on Lake Ontario, Canada, for instance. But a peninsula is usually bedrock of the same sort as the land around it, whereas a tombolo is a pile of sediment.
Tombolos are temporary things, mostly because the islands don't last long. The sea makes quick work of them, geologically speaking, wearing them down to the waterline in a few thousand years. Then the tombolo loses its protection and disappears.
Canada has a goodly share of tombolos because of its Ice Age history. The glaciers that recently covered Canada left behind great quantities of sand. Moreover, the land and sea have been sinking and rising with respect to each other there over the last 10,000 years as the ice came and went. So the shoreline has not been stable long enough for little offshore islands to be eroded away. The explanation to this photo from Newfoundland gives a hint of the tectonic shenanigans behind the tombolo there. That site, "Landforms of Canada," shows other tombolos—just search from the home page.
The last tombolo I'll show is in the Hawaiian Islands, at Poipu Beach on Kauai. What I love about this picture is not only that it's a tombolo, of course, but that it was taken (by Prof. Charles Benton) with a camera hanging from a kite. The things you find on the Web!
I've been collecting tombolo photos from readers and elsewhere in a tombolo gallery. Enjoy them and contribute!
PS: If you go tombolo hunting, be prepared to find lots and lots of sites about the other tombolo—a kind of Italian lace that is as labor-intensive as it is beautiful. I don't know why it has that name . . . do you?
