Tombolo!

I love this word. Almost as much a thalweg.

A Tombolo is a narrow neck of land that forms between the mainland and an island, or between two islands, as sand and sediment deposit between them. Waves hit a landform at a specific angle determined by surrounding currents. Over time this can build up to a sandbar or sand spit. If there happens to be an island or a rock nearby, and if the sediment builds up at exactly the right angle, then the two can join as one. Vegetation may take hold on the new land and further anchor a tombolo into place.


Apostle Islands, Wisconsin, USA

The first time I came across this phenomenon was during a trip to the Apostle Islands in Lake Superior. Stockton Island has a wonderful tombolo. Notice the distinctive sandy beach along the eastern side of the tombolo and the tuft of trees perched atop the islet that has been joined to Stockton.

A similar sandy beach formed on nearby Raspberry Island (map), although not quite as impressive. Here’s how it appeared on the ground:

Raspberry Island sandspit. Photo by howderfamily.com; (CC BY-NC-SA 2.0)
Raspberry Island shoreline

Saint Pierre and Miquelon, France

Then I came across another one as I researched my recent entry on the Territorial Collectivity of Saint Pierre and Miquelon. This tombolo joins two islands of approximately equal size, Miquelon, and Langlade. The remarkable thing about this tombolo is that it has formed eastern and western crescents to enclose a lagoon called the Grand Barachois.

There is also a much smaller tombolo at the northern end of this group that appears by zooming out the image. It joins the former islet of Le Cap to the others. The set of three combined take the name of the middle landmass, Miquelon.


Maria Island, Tasmania, Australia

Suitably sensitized to the phenomenon, I stumbled upon yet a third tombolo on Maria Island off the coast of Tasmania. In a bit of foreshadowing I’ll let you know I was checking this remote spot while researching what will become the next page in my Ferry Map series, expanded to include Australia. Indeed a ferry connects Maria Island to the mainland.


Mont Saint-Michel, France

Perhaps the most famous and recognizable tombolo of them all is the one that connects Mont Saint-Michel to the French mainland. This is an impressive and iconic structure known throughout the world. Notice the shadow of the castle clearly visible against the background of the surrounding terrain.


Cheung Chau, Hong Kong

Finally, a tombolo does not have to be in a remote and inaccessible location. Cheung Chau in Hong Kong is the home to more than 30,000 people.

Haven’t had enough of tombolos yet? There’s a big list of them on Wikipedia.

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