Wheeler Shale | |
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Stratigraphic range: Middle Cambrian ~ | |
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Elrathia kingii, famed trilobite of the Wheeler Shale. | |
Type | Geological formation |
Thickness | 100–200 m (330–660 ft) |
Lithology | |
Primary | Calcareous shale |
Other | Mudstone, shaley limestone and limestone |
Location | |
Coordinates | 39°15′N 113°20′W / 39.25°N 113.33°W |
Region | House Range and Drum Mountains, Millard Co., west Utah |
Country | United States |
Type section | |
Named for | House Amphitheater (Geographic feature and type locality) |
Named by | Charles Doolittle Walcott |
Part of a series on |
The Cambrian explosion |
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The Wheeler Shale (named by Charles Walcott) is a Cambrian ( c. 507 Ma) fossil locality world-famous [1] for prolific agnostid and Elrathia kingii trilobite remains (even though many areas are barren of fossils) [2] and represents a Konzentrat-Lagerstätte. Varied soft bodied organisms are locally preserved, a fauna (including Naraoia, Wiwaxia and Hallucigenia) and preservation style ( carbonaceous film) normally associated with the more famous Burgess Shale. [3] As such, the Wheeler Shale also represents a Konservat-Lagerstätten. [4]
Together with the Marjum Formation and lower Weeks Formation, the Wheeler Shale forms 490 to 610 m (1,610 to 2,000 ft) of limestone and shale exposed in one of the thickest, most fossiliferous and best exposed sequences of Middle Cambrian rocks in North America. [5]
At the type locality of Wheeler Amphitheater, House Range, Millard County, western Utah, the Wheeler Shale consists of a heterogeneous succession of highly calcareous shale, shaley limestone, mudstone and thin, flaggy limestone. [6] The Wheeler Formation (although the Marjum & Weeks Formations are missing) extends into the Drum Mountains, northwest of the House Range where similar fossils and preservation are found. [6]
Detailed work recognises a number of ~10 m thick lagerstätten sequences in the formation, each of which formed at a sea-level high stand [7] in deep water. [8] The lagerstätte were deposited by turbidities and mudslides onto an oxygenated sea floor. [7] The productive layers comprise mud and clay particles, with a tiny fraction of wind-blown quartz. [9]
The Wheeler Shale spans the Ptychagnostus atavus [10] and uppermost-Middle Cambrian Bolaspidella trilobite zones (See House Range for full stratigraphy).
Incomplete list of the fauna of the Wheeler Shale: [6] [11] [12] [13] [14] [15] [16] (Note: the preservation of hard bodied trilobite remains and soft bodied animals seems to be mutually exclusive within particular horizons.) [4] [17]
Wheeler Shale | |
---|---|
Stratigraphic range: Middle Cambrian ~ | |
![]()
Elrathia kingii, famed trilobite of the Wheeler Shale. | |
Type | Geological formation |
Thickness | 100–200 m (330–660 ft) |
Lithology | |
Primary | Calcareous shale |
Other | Mudstone, shaley limestone and limestone |
Location | |
Coordinates | 39°15′N 113°20′W / 39.25°N 113.33°W |
Region | House Range and Drum Mountains, Millard Co., west Utah |
Country | United States |
Type section | |
Named for | House Amphitheater (Geographic feature and type locality) |
Named by | Charles Doolittle Walcott |
Part of a series on |
The Cambrian explosion |
---|
![]() |
The Wheeler Shale (named by Charles Walcott) is a Cambrian ( c. 507 Ma) fossil locality world-famous [1] for prolific agnostid and Elrathia kingii trilobite remains (even though many areas are barren of fossils) [2] and represents a Konzentrat-Lagerstätte. Varied soft bodied organisms are locally preserved, a fauna (including Naraoia, Wiwaxia and Hallucigenia) and preservation style ( carbonaceous film) normally associated with the more famous Burgess Shale. [3] As such, the Wheeler Shale also represents a Konservat-Lagerstätten. [4]
Together with the Marjum Formation and lower Weeks Formation, the Wheeler Shale forms 490 to 610 m (1,610 to 2,000 ft) of limestone and shale exposed in one of the thickest, most fossiliferous and best exposed sequences of Middle Cambrian rocks in North America. [5]
At the type locality of Wheeler Amphitheater, House Range, Millard County, western Utah, the Wheeler Shale consists of a heterogeneous succession of highly calcareous shale, shaley limestone, mudstone and thin, flaggy limestone. [6] The Wheeler Formation (although the Marjum & Weeks Formations are missing) extends into the Drum Mountains, northwest of the House Range where similar fossils and preservation are found. [6]
Detailed work recognises a number of ~10 m thick lagerstätten sequences in the formation, each of which formed at a sea-level high stand [7] in deep water. [8] The lagerstätte were deposited by turbidities and mudslides onto an oxygenated sea floor. [7] The productive layers comprise mud and clay particles, with a tiny fraction of wind-blown quartz. [9]
The Wheeler Shale spans the Ptychagnostus atavus [10] and uppermost-Middle Cambrian Bolaspidella trilobite zones (See House Range for full stratigraphy).
Incomplete list of the fauna of the Wheeler Shale: [6] [11] [12] [13] [14] [15] [16] (Note: the preservation of hard bodied trilobite remains and soft bodied animals seems to be mutually exclusive within particular horizons.) [4] [17]