Arches National Park

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay

	Entrance to the park. Europeans are fascinated with the American West. I heard more French and German here than English.
	Left and below: views on the way from I-70 to Moab. The drab tan rocks are Cretaceous and Jurassic Mancos, Dakota and Morrison Formations.



	Left and below: views near Moab just south of Arches National Park.

	Triassic-Jurassic strata dipping into the Colorado River.

Park Avenue Area

Map based on National Park Service map

	Fault near Visitor Center Below: Park Avenue is lined by vertical rectangular slabs that reminded someone of Manhattan. The Entrada Sandstone is the principal cliff-forming unit.


	Two of the Three Gossips. The left one looks like a character from the Alien films. Below: views of Park Avenue. Cliffs are Entrada Sandstone, the valley floor and base of the cliffs is Carmel Formation.

	The Three Gossips. To the right is Sheep Rock. The inward curve of the left side suggests that Sheep Rock was part of an arch at one time.
	Left and below: Tower of Babel (right) and The Organ (left).


	Courthouse Towers: the lower end of Park Avenue.
	Cross-bedded Navajo dune sand near the Visitor Center
	View from above the Visitor Center looking toward Moab. The valley is the trace of the Moab Fault.

Map based on National Park Service map

	The first stage in the development of the arches is fracturing along parallel joints. The fracturing is especially well developed in certain areas near Moab and may be due to solution or flow of salt beneath the surface.
	The longer-lasting joint blocks remain as vertical fins
	Weathering attacks the lower more sheltered parts of the fins and creates arches. North Window at left is in a largely intact fin, South Window at right is in a much more degraded one that may eventually look like Delicate Arch.
	Collapse of arches may leave pinnacles.
	This and similar landscapes probably inspired the pod race landscape in Phantom Menace.







	Left and below: Double Arch


	End view of Parade of Elephants.
	Parade of Elephants.
	Late afternoon views of the La Sal Mountains. The resistant rocks of the La Sal Mountains are Tertiary intrusives.

Map based on National Park Service map

	There are two ways to see Delicate Arch. The longer way involves a trail directly to the arch. There is a shorter trail to a viewpoint. When they say you can't get to the arch from the viewpoint, they're not kidding. The arch is on the cliff at left.

	Left and below, views of the arch. This is obviously not a former bridge over a stream, but formed by weathering of a thin rock fin.

Below: cross-bedding in sandstone.

	An abandoned ranch at the Delicate Arch trailhead.

	A bright green conglomerate layer crops out near the ranch.

	Left, Closely jointed rocks of the Fiery Furnace. Below: Distant views of the canyon separating Delicate Arch from the Overlook.

Map based on National Park Service map



	Left and below: Skyline Arch

	Trailhead for Devil's Garden


	Weathered log on the trail.

	Left and Below: Tunnel Arch


	Landscape arch. Enjoy it while you can because nothing is forever in geology, and this is about as ephemeral as geology gets. Signs warn visitors to flee if they start hearing sounds from the rock.


	Left and below: General views of the Devil's Garden area.







	Left and below: views of the La Sal Mountains.

Created 7 April 2003, Last Update 08 June 2020