sandstone - Navajo sandstone teaching student specimens - Unit of 5 specimens

The Navajo Sandstone makes up the cross-bedded cliffs at Zion National Park in Utah. Locally it is poorly to moderately well cemented with silica cement. These specimens are moderately cemented and will stand up to student examination, though grains of sand can be rubbed off.  Sand grains in the Navajo are entirely frosted quartz dune sand, as the depositional environment of this sand was an immense inland sand sea or erg on the western edge of the supercontinent of Pangea. The erg covered much of what is now Utah and parts of Colorado, Wyoming, New Mexico and Arizona. The grains essentially sandblasted each other as they were blown by the wind. These are large enough that with a 10x hand lens, a student can see the frosted surface, a characteristic of this sandstone.  The Navajo was deposited during the Jurassic. Detrital zircon geochronology indicates that the Navajo erg received some of its sediments from the Appalachians via a Mississippi-scale river system. Near Hurricane, Utah th