Tarns are lakes that form in glacially-carved cirques. They are often dammed by moraines. If they are still associated with moving glaciers, tarns are often full of tiny, glacially-ground sediment that scatter light and can make the water appear colorful.

Where are tarns found?

Dotted around the mountains of the UK and the rest of the world are the secluded bowls of mountain lakes, more commonly known as tarns. They are sheltered and high, providing habitats for animals and plants and enriching the world of mountain walkers, spectacularly offsetting the rocky peaks above.

How do cirques and tarns form?

Cirques are bowl-shaped, amphitheater-like depressions that glaciers carve into mountains and valley sidewalls at high elevations. Often, the glaciers flow up and over the lip of the cirque as gravity drives them downslope. Lakes (called tarns) often occupy these depressions once the glaciers retreat.