Stop 3: An Ancient River
Walk up the trail and you are walking through an ancient riverbed. The water is gone, but you can reach out and feel the smooth river pebbles. Conglomerate is a type of sedimentary rock made up of rounded fragments cemented within a matrix of fine grain material.

All the water-worn river rocks you feel are embedded in sandstone. Sandstone is a sedimentary rock whose presence tells us a great deal about what the land was like when its sandy particles were deposited. Have you ever touched the soft, silty bottom of a river? That is what this stone once felt like, before it was cemented and compacted into rock over millions of years.

There are high concentrations of petrified wood deposits here because of the river, too. A dense forest surrounded the ancient river, much like the rain forest that today hugs Amazon River shores. When the trees died, some fell into the water. The “forests” of Petrified Forest National Park are actually petrified log jams where the dead trees were collected, buried, and petrified. Rainbow Forest is an example of where these log jams are eroding to the present surface.