Natural Bridges - Sipapu Bridge

Sipapu Bridge is carved into the Cedar Mesa Sandstone of Early Permian age. The Cedar Mesa Sandstone consists most of a light colored, fine-grained, quartz sandstone. It is tightly cemented by calcium carbonate (calcite) cement. Sedimentary structures preserved in the rock, particularly the thick layers of cross-bedded sandstone, are some of the obvious evidence that the sand was deposited in dunes. We can see similar sedimentary features forming in sand erg (dune field) environments today. The original sediments were deposited as "wind-blown dunes with mudstones on stream and floodplain surfaces" (Huntoon and others, 2000). Although fossils are extremely rare, tiny wind-transported fragments of shells can be seen in microscopic examination of some rock samples.