Tapeats Sandstone

rdf:langString Tapeats Sandstone

rdf:langString Early to Middle Cambrian

rdf:langString Muav Limestone- and Bright Angel Shale, resting on Tapeats and the Tonto Platform, inner canyon, Granite Gorge

rdf:langString Cambrian

rdf:langString northern Arizona , central Arizona, southeast California, southern Nevada, and southeast Utah

rdf:langString Except where underlain by the Sixtymile Formation, Cambrian Tapeats Sandstone is typically the lowest geologic unit, about 230 feet (70 m) thick, at its maximum, of the 5-member Tonto Group. It is famous for being the highly-resistant mostly-horizontal unit above the Great Unconformity expressed areally in the Grand Canyon of Arizona; also in other areas of Arizona and adjacent Nevada. The Tapeats Sandstone is the highly erosion-resistant unit laid upon the Vishnu Basement Rocks in the central, parts of east, and parts of west Grand Canyon, Arizona. The unit comprises the 'base horizontal unit' of the platform around Granite Gorge (Inner Gorge) on the Colorado River, and because of its hardness, creates the Tonto Platform upon which the slope-forming, Bright Angel Shale, (extensive, and distinctively soft drab-greenish), and above which low cliffs of Muav Limestone lie. The Tapeats unit is the basal unit of a typical marine transgression series of sandstone-(conglomerate)-shale-limestone, all part of a paleo sea, initially adjacent to land, the source of the Tapeats rocks-(conglomerates) and sand; (a regressing sequence has the reverse order). The Tapeats Sea at the late Cambrian ceased to deposit more Muav Limestone, and a period of erosion ensued, a deposition unconformity. The Tapeats Sandstone was laid upon the Vishnu Basement Rocks, after an unconformity of erosion, the Great Unconformity. Besides the erosion unconformity, the Grand Canyon Supergroup of the basement rocks are also at an angular unconformity, being an 7-member sequence tilted at 45 degrees. The horizontal Tonto Platform has hiking trails that cross it from the South Rim to North Rim, Grand Canyon for instance. The extensive Tonto Trail lies on parts of the Tapeats Sandstone, and the platform on the south side of Granite Gorge.

rdf:langString Noble

rdf:langString conglomeratic sandstone

rdf:langString Vishnu Basement Rocks, Unkar Group, Nankoweap Formation, Chuar Group, and Sixtymile Formation

rdf:langString sandstone and conglomerate