#872 Perito Moreno Glacier, Argentina

In any tourist brochure of Argentina, it is likely that there will be a photo of the Perito Moreno Glacier in Los Glaciares National Park. Perito Moreno isn't the largest glacier, nor the widest, but it's unique feature is that it buttresses up against a peninsula making it very easy to see it from above, allowing visitors to imagine how all glaciers calved valleys and lakes across the world. The other really cool thing about it is that when it hits the peninsula it forms a natural dam, causing the southern arm of Lago Argentino to be dammed and blocked from releasing its water into the main lake. Over time of course, the pressure builds up -- occasionally this breaks in a spectacular burst as the water pushes through all at once, but more often this carves a river under the glacier forming an ice-bridge (see pictures above) which eventually falls, also spectacularly, as it becomes too weak to support the weight of ice above. 

The north side of the glacier from the water -- the peninsula can be seen to the left side.

The peninsula forms a super lookout point from which to watch and hear the glacier calving - because it is a glacier that is growing, this happens often. The many kilometers of trails also hide native plants, animals and birds. We were lucky enough to see a woodpecker up close. The glacier can also be seen from air, boat (on both north and south sides of the glacier), and some visitors even walk on parts of it.

It is just one of many glaciers in Los Glaciares National Park that come from the Southern Patagonian Ice Field (shared with Chile) -- one of the largest masses of ice in the world. The glacier was named after important 19th Century Argentinian naturalist and explorer, Francisco Moreno.

Source: http://en.wikipedia.org/wiki/Perito_Moreno_Glacier