| 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. Although fossils are extremely rare, tiny sand-sized fragments of shells can be seen in microscopic examination of rock samples. Regional evidence indicate that the original sediments were deposited as "wind-blown dunes with mudstones on stream and floodplain surfaces" (Huntoon and others, 2000). 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, because we can see similar sedimentary features forming in sand erg (dune field) environments today. |
