Ischigualasto

Argentina's Valley of the Moon is a strange geological formation protected in a national park in the San Juan province in the northwestern region of the country, near the border that it shared with Chile. The Ischigualasto Provincial Park is huge at more than 230 square miles and is high above sea level at more than 4,000 feet.

The park features all of the vegetation you would typically find in this area - some small trees, cacti, and bushes - and is very dry with extreme temperatures. A near constant wind and little rainfall (almost all of which occurs during the summer) make this a harsh environment that is easy to visit but difficult to live in.

The park gets its nickname, the Valley of the Moon, because of the rugged, otherworldly geological structures that dot the landscape. Millions of years ago, this area was a floodplain dominated by strong rivers and rainfall. In the time of the dinosaurs, these rock deposits were formed slowly over time and have stood ever since. Some of these rocks are as round and smooth as marbles because of the constant wind that has shaped them through erosion. Among the rocks, giant (some more than 130 feet tall) petrified tree trunks attest to the rich vegetation that once fed the similarly giant creatures that walked among them.

Today, an area around the Valley of the Moon is known as holding some of the world's oldest dinosaur remains. It is a popular - and important - site for paleontological research.