Something dramatic happened about 500 million years ago called the Cambrian "explosion," during which an incredible diversity ...

The age of the fossil must be determined so ... it is possible to work out the relative ages of rocks. In the Grand Canyon, the layers of strata are nearly horizontal. Most sediment is either ...

Bill Hatcher The Shamans' Gallery, a rock art panel that stretches ... I will just say, since the beginning of the ice age.” On our last day in the Grand Canyon, Bill, Greg and I made a ...

The Grand Canyon was carved out of rock by the Colorado River over millions ... but changed due to rising sea-levels following the Ice Age. How has glaciation shaped the landforms of the Northern ...