(in Glen Canyon Group)
Figure 1: Paleogeographic map of the Early Jurassic, Wingate Sandstone, Navajo Sandstone, and Kayenta Formation. (Blakey, 2008)
Early Jurassic, 199.6 million years ago to 175.6 million years ago
Fluvial (river) environment
The Wingate erg was reworked by river currents in the time period when the Kayenta formation was being deposited.
Seasonal climate, rainy summers and dry winters
The Kayenta Formation is Jurassic in age and makes up the middle third of the three-part section that make up the Glen Canyon Group. The Wingate Sandstone is below the Kayenta, while the Navajo Sandstone is above it. The Kayenta Formation is about 350 feet thick and range in color from red, to maroon, to brown (Mathis, 2000).
The Kayenta is composed of sandstones, siltstones, and conglomerates that interbed (or alternate) within each other (Bates et al., 1984). At the top of the Kayenta, where it meets the Wingate, and the bottom of the Kayenta, where it meets Navajo, are contacts that are gradational (Mathis, 2000). Due to this, sometimes it is challenging to differentiate between the Wingate and the Kayenta formations but there are some clues that might aid in discerning the two. The Wingate Sandstone is eolian in origin meaning it was formed/deposited by the wind. In contrast, the Kayenta formation represents a fluvial (pertaining to a river) environment (Bates et al., 1984). According to Friz 1980, the rivers that formed the Kayenta were traveling in a westward to southwestward direction. In the Kayenta, there are small cross-beds (layers of sediment that are tilted at an angle) in contrast to the Navajo and Wingate, which have large cross-beds (Morris et al., 2003). Cross-beds that look like lenses (lenticular) often are indicative of the Kayenta. The Wingate fractures vertically, while the Kayenta fractures horizontally. This fracturing is readily apparent in “the castle” rock structure seen at the Visitors Center of the park (Figure 1). The Kayenta usually weathers as low cliffs and ledges (Morris et al., 2003).
Sites Best to See it:
Stop 2-7: “The Castle”
Figure 2: “The castle” rock structure is north of the Visitors Center of the park. The Wingate (upper light tan colored rock) fractures vertically, whereas the Kayenta (reddish brown, overlying the Wingate as shown to the far right of the Wingate in the background) breaks horizontally.
For a complete list of references please go to the References page.
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Disclaimer: The information is property of the University of Utah. Unless cited, images and files found on this site have been taken or created by the Geology and Geophysics Department at the University of Utah. Any use of these images should be cited appropriately. The stratigraphic column is from: Mathis, A. C. 2000. Capitol Reef National Park and Vicinity Geologic Road Logs, Utah, in: P.B. Anderson and D.A. Sprinkel (eds.) Geologic Road, Trail, and Lake Guides to Utah’s Parks and Monuments Utah Geological Association Publication 29. http://www.utahgeology.org/uga29Titles.htm
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