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LOCATION:  Monument Valley Navajo Tribal Park is located in northern Arizona adjacent to the Utah Border.  The Visitor Center is found along Monument Valley Road, east of Route 163 and the town of Goulding, UT.

GEOLOGIC FEATURES: Cross-bedding (Aeolian Sand Dunes); Floodplain deposits; Unconformity; Pinnacles (Pillars, Spires, Towers); Mesas and Buttes.

DESCRIPTION: Monument Valley was formed from erosion by streams, rivers and wind during the last 50 million years into lands uplifted as a result of the Laramide Orogeny (Upper Cretaceous to Lower Tertiary).


Rocks in Monument Valley include the Lower Permian Organ Rock Shale, the Lower Permian de Chelly Sandstone, the Lower Triassic Moenkopi Fm. and the Upper Triassic Shinarump Conglomerate.


The dark red mudstone and siltstone of the Organ Rock Fm. represents floodplain and channel deposits.  The de Chelly Sandstone was formed from aeolian sand dunes.  The red-brown Moenkopi represents a floodplain environment while the Upper Triassic Shinarump Conglomerate of the Chinle Fm. preserves the deposits of braided streams.  The widespread unconformity at the base of the Upper Triassic Shinarump is one of the most prominent ones within the Colorado Plateau.


The resistance of the Shinarump to erosion is responsible for the vertical cliffs, pinnacles, and buttes of Monument Valley as running water more easily erodes the rock layers below the well-cemented, hard conglomerate.


(1) Explain the necessity of a resistant caprock, such as the Shinarump Fm., in the development of Monument Valley’s distinctive topography.

(2) Describe the geologic origin of the unconformity at the base of the Shinarump Conglomerate.

(3) Explain the red color found in rocks of Monument Valley.

(4) CHALLENGE – Explain the circumstances that might explain the shift in depositional environments from the those found in the Organ Rock Shale, the de Chelly Sandstone, and the Moenkopi Formations.


-Hull, D. Monument Valley Scenic Drive (Everything You Need to Know). My Itchy Travel Feet. Accessed on July 11, 2022 from

-Monument Valley: Ultimate Guide for First Time Visitors. Earth Trekkers. Accessed on July 11, 2022 from

-Monument Valley. Utah’s Canyon Country. Accessed on July 11, 2022 from Geology. Accessed on July 11, 2022 from


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Figure 1 - West Mitten, Right Mitten, and Merrick Buttes located near the entrance to the Park

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de Chelly Sandstone

Organ Rock Fm

Moenkopi Fm.

Shinarump Fm

Figure 2 - Merrick Butte, to the right, displays distinct geologic formations - The Organ Pipe Shale, de Chelly Sandstone, Moenkopi Fm. and Shinarump Conglomerate 

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Figure 3 - The 3 Sisters are pinnacles carved within the de Chelly Sandstone.  The Moenkopi and Shinarump cap the Butte to the right while the Organ Rock Formation underlies the de Chelly.

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IFigure 4 - "Totem Poles" are carved out of the de Chelly Sandstone. 

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Figure 5 - A view from John Ford's Point. John Ford was a Hollywood director who used parts of Monument Valley as a backdrop to his films.

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Figure 6 - A view from the North Window Overlook illustrating the four rock formations found in Buttes around the Park (see Figure 2).

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Figure 7 - View from North Window Overlook. The floodplain deposits of the Organ Rock Fm are seen in the foreground as they transition into the harder sandstones of the de Chelly Fm.

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Figure 8 - West Mitten Butte is seen in the right of the photo.

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Figure 9 - Pillars and buttes as viewed from North Window Overlook.

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Figure 10 - The distinctive silhouette of pinnacles, buttes, and mesa found in Monument Valley popularized by the movie Forrest Gump.  Forrest Gump point, with views from the movie, can be accessed along Route 163,  several miles north of the Park entrance.

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