Summerville Formation | |
---|---|
Stratigraphic range: Oxfordian | |
Type | Geological formation |
Unit of | San Rafael Group |
Sub-units | Bluff Sandstone |
Underlies | Morrison Formation |
Overlies | Todilto & Curtis Formations |
Thickness | 100 m (330 ft) |
Lithology | |
Primary | Mudstone, sandstone |
Other | Gypsum |
Location | |
Coordinates | 39°12′58″N110°32′38″W / 39.216°N 110.544°W |
Approximate paleocoordinates | 31°54′N54°42′W / 31.9°N 54.7°W |
Region | Four Corners, (Southwestern United States) |
Country | United States |
Extent | Henry Mountains, Paradox Basin |
Type section | |
Named for | Summerville Point, Emery County, Utah |
Named by | James Gilluly & J.B. Reeside Jr. |
Year defined | 1928 |
Summerville Formation outcrops in Utah, Colorado and New Mexico |
The Summerville Formation is a geological formation in New Mexico, Colorado, and Utah of the Southwestern United States. It dates back to the Oxfordian stage of the Late Jurassic. [1]
The formation consists of up to 100 meters (330 ft) of red mudstone, with thin interbeds of green and red sandstone. The lower portion of the formation shows polygonal desiccation cracks and localized salt-hopper casts while the upper portion contains considerable gypsum, consistent with deposition in a sabkha on the margin of the Sundance Sea.It is exposed in the San Rafael Reef, the Waterpocket Fold, in the Henry Mountains, with additional exposures scattered across the region from the San Rafael Reef to the Paradox Basin, [2] and in north-central New Mexico. [3] The thin bedding is characteristic throughout the formation, but gypsum is not found in the San Juan Basin and some conglomerate is found on the south and southwestern margins of the formation. [4] The correlation of late Jurassic beds in northwestern New Mexico with the Summerville Formation in Utah has been questioned, and it has been suggested that they be assigned to the Beclabito Formation instead. [5]
The Summerville Formation rests conformably on the underlying Curtis Formation (Utah and western Colorado) or Todilto Formation (southwest Colorado and New Mexico) but is separated from the overlying Morrison Formation by the regional J5 unconformity. [1] It thins significantly in the Moab-La Sal area, the likely area of the divide between the marine Curtis basin to the northwest and the salina lake Todilto basin to the southeast. Here the formation is just 1.2 meters (3.9 feet) thick and rests directly on Entrada Sandstone. In many locations the Summerville is separated from the Morrison by eolian sandstones, such as the Bluff Sandstone, variously assigned to the Morrison Formation or the San Rafael Group. The Morrison Formation represents a return to more humid conditions with increased clastic input. [6]
The Bell Ranch Formation of northeastern New Mexico is correlative with the Summerville Formation. [7]
The Summerville Formation is interpreted as recording a regression of the Sundance Sea to the north, with simultaneous infilling of both the Curtis and Todilto basins. This produced a depositional environment of very low relief, in which occasional encroachments of eolian sand during times of drought were subsequently worked into thin strata by wave action in ephemeral saline lakes. [6]
The formation is almost completely lacking in body fossils. [8] However, theropod tracks were found in the formation in Utah, New Mexico, and Colorado. [9]
Avemetatarsalians of the Summerville Formation | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Pteraichnus [10] | P. saltwashensis [10] | Arizona [10] | Pterosaur trackways. Includes the P. saltwashensis type locale. [10] Specimens housed at the University of Utah. [10] These tracks may actually be from the Morrison Formation. [10] | |||
Indeterminate | Arizona, near Summerville [10] Also present in Colorado (Cactus Park, Furnish Canyon, Colorado National Monument) and Utah (Delmonte Mines, Starr Springs, Flaming Gorge, Ferron, Moab, Duchesne County). [10] | Summerville, Furnish Canyon, Cactus Park, Delmonte Mines, Starr Springs, Ferron, and Moab specimens are housed in the University of Colorado's Dinosaur Tracks Museum in Denver. [10] The Flaming Gorge and Colorado National Monument tracks remains in the field. [10] Ferron specimens are also housed at the University of Utah. [10] | ||||
Color key
| Notes Uncertain or tentative taxa are in small text; |
The formation was first defined in 1928 for exposures in the San Rafael Reef. [2] Similar beds in northeastern Arizona and the San Juan Basin are assigned to the Wanakah Formation, [11] but continue to be assigned to the Summerville Formation in north-central New Mexico. [7] [3]
The Entrada Sandstone is a formation in the San Rafael Group found in the U.S. states of Wyoming, Colorado, northwest New Mexico, northeast Arizona, and southeast Utah. Part of the Colorado Plateau, this formation was deposited during the Jurassic Period sometime between 180 and 140 million years ago in various environments, including tidal mudflats, beaches, and sand dunes. The Middle Jurassic San Rafael Group was dominantly deposited as ergs in a desert environment around the shallow Sundance Sea.
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
The Navajo Sandstone is a geological formation in the Glen Canyon Group that is spread across the U.S. states of southern Nevada, northern Arizona, northwest Colorado, and Utah as part of the Colorado Plateau province of the United States.
The Moenkopi Formation is a geological formation that is spread across the U.S. states of New Mexico, northern Arizona, Nevada, southeastern California, eastern Utah and western Colorado. This unit is considered to be a group in Arizona. Part of the Colorado Plateau and Basin and Range, this red sandstone was laid down in the Lower Triassic and possibly part of the Middle Triassic, around 240 million years ago.
The Glen Canyon Group is a geologic group of formations that is spread across the U.S. states of Nevada, Utah, northern Arizona, north west New Mexico and western Colorado. It is called the Glen Canyon Sandstone in the Green River Basin of Colorado and Utah.
The San Rafael Group is a geologic group or collection of related rock formations that is spread across the U.S. states of New Mexico, Arizona, Utah and Colorado. As part of the Colorado Plateau, this group of formations was laid down in the Middle Jurassic during the Bajocian, Bathonian and Callovian Stages.
The Carmel Formation is a geologic formation in the San Rafael Group that is spread across the U.S. states of Wyoming, Utah, Colorado, north east Arizona and New Mexico. Part of the Colorado Plateau, this formation was laid down in the Middle Jurassic during the late Bajocian, through the Bathonian and into the early Callovian stages.
The Wingate Sandstone is a geologic formation in the Glen Canyon Group of the Colorado Plateau province of the United States which crops out in northern Arizona, northwest Colorado, Nevada, and Utah.
The Kayenta Formation is a geological formation in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. Traditionally has been suggested as Sinemurian-Pliensbachian, but more recent dating of detrital zircons has yielded a depositional age of 183.7 ± 2.7 Ma, thus a Pliensbachian-Toarcian age is more likely. A previous depth work recovered a solid "Carixian" age from measurements done in the Tenney Canyon. More recent works have provided varied datations for the layers, with samples from Colorado and Arizona suggesting 197.0±1.5-195.2±5.5 Ma, while the topmost section is likely Toarcian or close in age, maybe even recovering terrestrial deposits coeval with the Toarcian Oceanic Anoxic Event. This last age asignation also correlated the Toarcian Vulcanism on the west Cordilleran Magmatic Arc, as the number of grains from this event correlate with the silt content in the sandstones of the upper layers.
Cedar Mesa Sandstone is a sandstone member of the Cutler Formation, found in southeast Utah, southwest Colorado, northwest New Mexico, and northeast Arizona.
The Bell Ranch Formation is a Late Jurassic (Kimmeridgian) geologic formation in eastern and northeastern New Mexico and the western Oklahoma panhandle. Fossil theropod tracks have been reported from the formation.
The Nugget Sandstone is a Late Triassic to Early Jurassic geologic formation that outcrops in Colorado, Idaho, Wyoming, and Utah, western United States.
The Todilto Formation is a geologic formation in northern New Mexico and southeastern Colorado. It preserves fossils dating back to the Callovian stage of the middle Jurassic period.
The Curtis Formation is a geologic formation in Utah. It preserves fossils dating back to the Callovian age of the Jurassic period.
The Sinbad Formation is a geologic formation in Utah initially named and described by James Gilluly and J. B. Reeside Junior in the 1920s. It is known for preserving fossils dating back to the Early Triassic epoch.
The Zuni Sandstone is a geologic formation in west-central New Mexico. It marks the southernmost limit of Jurassic fluvial and lacustrine sedimentary formations, which pinch out to leave a single sandstone body.
The Bluff Formation is a geological formation found in the Four Corners area. It was deposited in the late Jurassic Period.
The Beclabito Formation is a late Jurassic sedimentary geologic formation, found in northwestern New Mexico and northeastern Arizona.
Wild Horse Butte is a 5,760-foot (1,756-meter) elevation summit located in Goblin Valley State Park, in Emery County, Utah. Wild Horse Butte is situated 2.3 mi (3.7 km) west of Mollys Castle, and the top of this geological feature rises over 800 feet above its surrounding terrain, with precipitation runoff from Wild Horse Butte entering the Colorado River drainage basin. John C. Frémont's fifth expedition (1853–1854) stopped at Wild Horse Butte in January 1854, when Solomon Nunes Carvalho recorded a daguerreotype image of this butte.