Condensed Geology: Arches, Utah [Map] Arches NP

Geology of Arches is defined by sandstone fins, forming at the top of a salt and gypsum anticlines.

Story.

Figure 1
Figure 1

500-280 MYA. Utah is covered by sea (1) that becomes isolated and hypersaline toward the Pennsylvanian.

 

Figure 2
Figure 2

280 MYA. The sea evaporates during the Pennsylvanian; a thick layer of salt and gypsum (2) is deposited and covered by other sediments.

 

Figure 3
Figure 3

250-150 MYA. A series of huge deserts cover Utah with windblown sand, depositing thick layers of sandstone (3) during Triassic and Jurassic.

 

Figure 4
Figure 4

50(?) MYA. Under the pressure of overlying rocks the salt and gypsum flow to where the overburden is locally thinner, forming anticlines (4) and doming the sandstone.

 

Figure 5
Figure 5

Today. Sandstone domes form parallel cracks (5) along the top of the anticline ridges.

 

Figure 6
Figure 6

Today. Erosion deepens the cracks, forming rows of parallel sandstone fins. In some places the central portions of the fins are eroded (6) forming windows and arches.

 

References.

Halka Chronic Roadside Geology of Utah (Roadside Geology Series) Mountain Press Publishing Company, 1990, ISBN: 0-87842-228-5

Attribution.

© October 28, 2014, Yuri Wolf / YuriKira.com

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