What do the three have in common? They all share the same unique rock formation. It is so rare that you can only find it at these three locations at Gilbert Hill in Mumbai India, the Devils Postpile in California, and in Devils Tower in Wyoming.

Geologists date some of these rock formations back 65 million years. The dinosaurs became extinct around this time. If these rock walls could talk, they could tell us so much about our Earth's history. The rocks at the Gilbert Hill are the oldest dating back 66 million years. The National Park Service has dated Devils Tower back 50 million years. As far as Devils Postpile, it's a baby as it was only created 100 thousand years ago.

The best geologic theories believe a process called intrusion created these three natural monuments. Intrusion means magma injected itself between two layers of softer rock. The surrounding rock is more vulnerable to erosion from wind and water. Then the inner layer which is a harder igneous rock stays intact much longer. In the case of Devils Tower, the softer rock layer disintegrated away about 10 million years ago leaving the monolith as it is today.