Even the balmy tropics may have once been crushed by colossal masses of ice.

A shallow sea advances and retreats several times during this period, leaving behind the layers named Kaibab Limestone, Toroweap Formation, and Hermit Shale. The Coconino Sandstone layer was ...

The fossils included plant imprints, animal tracks, and pieces of evidence of water bodies that were well-preserved between ...

As you might have guessed, sandstone started out as sand on the surface, but is compacted together by different activities, such as grains in rivers becoming buried by layers and layers of silt.

Sedimentary rock like sandstone is laid down in layers. Changes in the size and chemistry of the layers can tell us about climate conditions millions of years ago. Rocks and fossils can be studied ...