File:Entrada Sandstone (Middle Jurassic; Arches National Park, Utah, USA) (30494313656).jpg
Sandstones & siltstones in the Jurassic of Utah, USA. (photos by William Meikle; photo stitch by Mary Ellen St. John)
Date
Source
Entrada Sandstone (Middle Jurassic; Arches National Park, Utah, USA)
Author
James St. John
The principle scenery at Arches National Park consists of numerous natural arches developed in the Jurassic-aged Entrada Sandstone. The reddish-brown coloration is due to significant hematite impurity (Fe2O3 - iron oxide).
In the cliffs shown above, the massive-bedded upper part is relatively hard quartzose sandstones of the Slickrock Member. The thin-bedded interval below is relatively soft interbedded siltstones and mudshale of the Dewey Bridge Member. Differential weathering and erosion of these two units results in numerous natural arches and some balancing rocks.
Stratigraphy: Slickrock Member over the Dewey Bridge Member, Entrada Sandstone, Middle Jurassic
Locality: Arches National Park, next to the town of Moab, southern Grand County, eastern Utah, USALicensing
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/30494313656 (archive). It was reviewed on 6 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
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