Coal seam in the Blackhawk Formation, Skyline Mine
The Blackhawk Formation is a geological formation in east-central Utah, USA. It was named for the former town of Blackhawk on the east side of the Wastach Plateau, Carbon County.[1] The formation is composed of mostly light-brown, light-gray and brownish-gray, thin- to medium-bedded, fine- to medium-grained quartzose sandstone that is interbedded with shaly siltstone, shale, carbonaceous shale, and coal.[2] There are many thin to thick bituminous coal seams, including several economically important beds, such as the Sunnyside Coal. The formation thickness ranges from about 120 m (400 ft) to about 270 m (900 ft). It conformably overlies the Star Point Sandstone and unconformably underlies the Castlegate Sandstone.
The Blackhawk Formation is the withdrawal (regressive) phase of the Cretaceous Seaway in eastern Utah.
The sediments that formed the Blackhawk Formation originated from erosion of the Sevier Uplift in western Utah.[2] This sediment was transported eastwards by rivers and deposited on the western coast of the Cretaceous Seaway. At this time, the Seaway was also withdrawing (regression) eastwards, but this was irregular, with occasional episodes of the sea advancing (transgression) to cover coastal lands. This transgression was partially as a result of fluctuating (eustatic) global sea level changes and partly as a result of the shift position of the deltas.[3][4] These events created wedges of terrestrial sedimentary rock between wedges of marine sedimentary rock (Mancos Shale). These wedges of the Blackhawk Formation have been given names and many of them contain economically important bituminous coal zones, such as the Kenilworth Coal that is up to 11 m (37 feet) thick.[3] The coast probably resembled the Gulf Coast today, being composed of a broad coastal plain, with meandering rivers that ended in wave-dominated deltas. These deltas were flanked by sandy beaches.[4] Swamps were probably developed on the delta plains and on the floodplain (bottomlands) adjacent to the meandering rivers, rather than in brackish-water of lagoons because of the low sulfur content of the coals.[4]
Hadrosaur track in the ceiling of a coal mine.
Paleontology
Fossil plants are extremely common in the Blackhawk Formation.[5] Their distribution is closely tied to specific environments, just like plants are today. The plant community of the swamp environment was dominated by the evergreen conifer Sequoia cuneata and a deciduous angiosperm tree Rhamnites eminens. Other, less abundant trees include Protophyllocladus polymorpha, Moriconia cyclotoxon, Brachyphyllum squammnosum, Podozamites sp., and the angiosperms “Cissus” marginata, Platanus raynoldsii, "Cornus” praetimpressa, Dryophyllum subfalcatum, “Ficus” planicostata, and Myrtophyllum torreyii.[6] Near the swamp margins a small palm, Phoenocites imperialis, grew in thickets. The palm Sabalites grayanus was also present, although not in abundance. The herbaceous understory was composed entirely of two ferns, Cyathea pinnata and Onoclea herbridica. The aquatic plants include a water lily, Nymphaeites dawsoni, a water chestnut, Trapa paulula, and a cattail, Cyperacites. The bottomland community was dominated by the angiosperm trees Platanus raynoldsii and Dryophyllum subfalcatum. Other angiosperm trees also present, but in lesser abundance include Phoenocites, “Cercidophyllum” arcticum, “Ficus” laurophylla, Laurophyllum coloradensis, Manihotites georgiana, Platanus alata, Menispermites sp., and “Viburnum” antiquum; conifers were absent. Ferns were the only understory plants. Overall, the plant communities looked similar to those along the Gulf Coast, although the Blackhawk communities had a larger proportion of conifers and few, if any herbaceous angiosperms in the swamp and bottomland forest understories.[6] Based on angiosperm leaf physiognomy (leaf size, leaf margins and dripping tips), the predominance of medium-size leaves with entire (non-serrated) margins and dripping tips, indicate that the climate was warm temperate- to subtropical, but not tropical.[5] Growth rings in conifer logs and leaf mats from seasonal shedding, also suggests the climate was seasonal. Charcoal occurs indicating that wildfires occasionally swept through the area during the dry season.
Map of dinosaur tracks in a coal mine in the Blackhawk Formation. Also visible are tree roots and large branches and logs.
Various vertebrates are known to have inhabited the Blackhawk paleoenvironments. These include rare bone fossils of fishes, turtles and crocodiles in the collections of the Prehistoric Museum in Price Utah. The most abundant vertebrate fossils are the tracks of dinosaurs, including the blunt, three-toed hadrosaurs, long, slendered toed theropods, and the short-wide, four-toed ceratopsians.[7][8] Most of these tracks are found in the mine roof when the coal is removed. They formed when the foot of the living animals pressed into the peat of the swamp bottom. Later, sheets of sand were deposited across the swamp during floods filling in the footprints. Thus, the footprints seen represent the bottom of the foot. The larger tracks used to be removed because of their tendency to fall from the roof and many houses in Carbon and Emery Counties in Utah had a footprint or two in their yards.
Some tracks have elongated heels, which indicate the individuals slipping on exposed wet mud (slipping does not happen in standing water). One of these elongated hadrosaur tracks was named Dinosauropodes and heralded as the footprint of the world's biggest dinosaur.[9] The largest hadrosaur tracks are over 62 cm (24 in.) wide, indicating the presence of huge hadrosaurs the size of Shantungosaurus from China. As yet, no bones of hadrosaurs this size are not known from the Blackhawk Formation. Possible pterosaur tracks have been reported[10] from the Kenilworth Mine near Helper, Utah. Problematically, however, these tracks seem to be only those of the wing-hand and do not include any foot (pes) tracks. These asymmetrical three-digit tracks were previously thought to belong to the aquatic bird Hesperornis.[7] A few, rare dinosaur bones have been recovered from the mines, including ceratospian and possibly hadrosaur.[11]
The hadrosaur tracks from the Blackhawk Formation provide insights into the behavior of these dinosaurs that is not available from their skeletons.[8] These tracks provide a snapshot into the lives of these dinosaurs. First, hadrosaur tracks are by far the most abundant of the track types, which supports the observation from bone beds that hadrosaurs were numerically the most abundant dinosaurs during the Late Cretaceous of North America. We can see this in a map of tracks from the Kenilworth Mine. Although one individual milling around can leave hundreds of tracks, the abundance of different sized tracks and that some trackways indicate individuals passing through suggests that a herd of different-sized hadrosaurs had made the tracks. Some of the tracks seems to show individuals standing at the base of conifer trees, whose spreading roots indicate trees in growth position (see red tracks on map). These individuals may have been feeding,[8] thus supporting the hypothesis by Yale paleontologist John Ostrom that hadrosaurs fed on conifers. The map also shows numerous isolated tracks due in part to the removal of some tracks by the miners or to the differential firmness of the swamp floor. Firmer mud, such as late in the dry season or during prolonged droughts, would not leave deep tracks; in support of this, mud cracks are known from the mines,[7] as is charcoal from fires (called fusain). The hadrosaur tracks from the Blackhawk Formation also contain some of the smallest known tracks. Assuming that the smallest ones, ~3.5 cm (1.25 in) are real and not carved, these would indicate hatchling-sized individuals around 40 cm (16 in,) long.[8] Other, slightly larger tracks preserved on a rock slab are reliably 4 to 5 cm (1.5-2 in.) wide and made by individuals a little less than a meter long. The presence of these small tracks from coal swamp deposits are important because they indicate the presence of nearby nesting grounds, which unfortunately, have not yet been found. The full size range of tracks from the coal mines indicate individuals from 0.4 m (1.25 ft.) to 16 m (52.5 ft.) and that this species spent its entire life in the swamps.
Unfortunately, because of the use of long-wall mining now, which is less wasteful than the old room-and-pillar method, the recovery of dinosaur tracks and bones from mines in the Blackhawk Formation, has all but dried-up.
The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation stretches over portions of Montana, North Dakota, South Dakota, and Wyoming. In Montana, the Hell Creek Formation overlies the Fox Hills Formation. The site of Pompeys Pillar National Monument is a small isolated section of the Hell Creek Formation. In 1966, the Hell Creek Fossil Area was designated as a National Natural Landmark by the National Park Service.
The Dinosaur Park Formation is the uppermost member of the Belly River Group, a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 76.9 and 75.8 million years ago. It was deposited in alluvial and coastal plain environments, and it is bounded by the nonmarine Oldman Formation below it and the marine Bearpaw Formation above it.
The Fruitland Formation is a geologic formation found in the San Juan Basin in the states of New Mexico and Colorado, in the United States of America. It contains fossils dating it to the Campanian age of the late Cretaceous.
The Laramie Formation is a geologic formation of Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States. It was deposited on a coastal plain and in coastal swamps that flanked the Western Interior Seaway. It contains coal, clay and uranium deposits, as well as plant and animal fossils, including dinosaur remains.
The Naturita Formation is a classification used in western Colorado and eastern Utah for a Cretaceous Period sedimentary geologic formation. This name was "applied to the upper or carbonaceous part of Dakota Group" by R.G. Young in 1965, naming it for Naturita, Colorado. The name was not generally accepted for that strata, and it has not been used by U.S. Geological Survey authors.
The St. Mary River Formation is a geologic formation of Late Cretaceous age of the Western Canada Sedimentary Basin in southwestern Alberta and northwesternmost Montana. It was first described from outcrops along the St. Mary River by George Mercer Dawson in 1883, and it takes its name from the river.
Gething Formation is a stratigraphic unit of Lower Cretaceous (Aptian) age in the Western Canada Sedimentary Basin. It is present in northeastern British Columbia and western Alberta, and includes economically important coal deposits.
The Crevasse Canyon Formation is a coal-bearing Cretaceous geologic formation in New Mexico and Arizona.
The Menefee Formation is a lower Campanian geologic formation found in Colorado and New Mexico, United States.
The Mowry Shale is an Early Cretaceous geologic formation. The formation was named for Mowrie Creek, northwest of Buffalo in Johnson County, Wyoming.
The Chacarilla Formation is an Oxfordian to Early Cretaceous geologic formation of the Tarapacá Basin in northern Chile, close to the border with Bolivia. The marine and fluvial formation preserves several dinosaur trackways and has been declared a Natural Sanctuary in 2004.
Kosmoceratops is a genus of ceratopsid dinosaur that lived in North America about 76–75.9 million years ago during the Late Cretaceous period. Specimens were discovered in Utah in the Kaiparowits Formation of the Grand Staircase-Escalante National Monument in 2006 and 2007, including an adult skull and postcranial skeleton and partial subadults. In 2010, the adult was made the holotype of the new genus and species Kosmoceratops richardsoni; the generic name means "ornate horned face", and the specific name honors Scott Richardson, who found the specimens. The find was part of a spate of ceratopsian discoveries in the early 21st century, and Kosmoceratops was considered significant due to its elaborate skull ornamentation.
Paleontology in West Virginia refers to paleontological research occurring within or conducted by people from the U.S. state of West Virginia. West Virginia's fossil record begins in the Cambrian. From that time through the rest of the early Paleozoic, the state was at least partially submerged under a shallow sea. The Paleozoic seas of West Virginia were home to creatures like corals, eurypterids, graptolites, nautiloids, and trilobites at varying times. During the Carboniferous period, the sea was replaced by lushly vegetated coastal swamps. West Virginia is an excellent source of fossil plants due to these deposits. These swamps were home to amphibians. A gap in the local rock record spans from the Permian to the end of the Cenozoic. West Virginia was never the site of glacial activity during the Ice Age, but the state was home to creatures like mammoths, mastodons, and giant ground sloths. One local ground sloth, Megalonyx jeffersonii, was subject to the scholarly investigations of Thomas Jefferson, who misinterpreted the large-clawed remains as belonging to a lion-like predator. In 2008, this species was designated the West Virginia state fossil.
Paleontology in Georgia refers to paleontological research occurring within or conducted by people from the U.S. state of Georgia. During the early part of the Paleozoic, Georgia was largely covered by seawater. Although no major Paleozoic discoveries have been uncovered in Georgia, the local fossil record documents a great diversity of ancient life in the state. Inhabitants of Georgia's early Paleozoic sea included corals, stromatolites, and trilobites. During the Carboniferous local sea levels dropped and a vast complex of richly vegetated delta formed in the state. These swampy deltas were home to early tetrapods which left behind footprints that would later fossilize. Little is known of Triassic Georgia and the Jurassic is absent altogether from the state's rock record. During the Cretaceous, however, southern Georgia was covered by a sea that was home to invertebrates and fishes. On land, the tree Araucaria grew, and dinosaurs inhabited the state. Southern Georgia remained submerged by shallow seawater into the ensuing Paleogene and Neogene periods of the Cenozoic era. These seas were home to small coral reefs and a variety of other marine invertebrates. By the Pleistocene the state was mostly dry land covered in forests and grasslands home to mammoths and giant ground sloths. Local coal mining activity has a history of serendipitous Carboniferous-aged fossil discoveries. Another major event in Georgian paleontology was a 1963 discovery of Pleistocene fossils in Bartow County. Shark teeth are the Georgia state fossil.
Paleontology in Alabama refers to paleontological research occurring within or conducted by people from the U.S. state of Alabama. Pennsylvanian plant fossils are common, especially around coal mines. During the early Paleozoic, Alabama was at least partially covered by a sea that would end up being home to creatures including brachiopods, bryozoans, corals, and graptolites. During the Devonian the local seas deepened and local wildlife became scarce due to their decreasing oxygen levels.
Paleontology in Alaska refers to paleontological research occurring within or conducted by people from the U.S. state of Alaska. During the Late Precambrian, Alaska was covered by a shallow sea that was home to stromatolite-forming bacteria. Alaska remained submerged into the Paleozoic era and the sea came to be home to creatures including ammonites, brachiopods, and reef-forming corals. An island chain formed in the eastern part of the state. Alaska remained covered in seawater during the Triassic and Jurassic. Local wildlife included ammonites, belemnites, bony fish and ichthyosaurs. Alaska was a more terrestrial environment during the Cretaceous, with a rich flora and dinosaur fauna.
The Minnes Group, originally named the Minnes Formation, is a geologic unit of latest Jurassic to earliest Cretaceous age in the Western Canada Sedimentary Basin. It is present in the northern foothills of the Canadian Rockies and the adjacent plains in northeastern British Columbia and west-central Alberta. Its strata include natural gas reservoirs and minor coal deposits. Fossil dinosaur tracks have been described from one of its formations.
The Ferron Sandstone Member of the Mancos Shale is a geologic unit in Utah. It preserves fossils dating back to the Cretaceous period; and more specifically the middle Turonian.
The Mesaverde Group is a Late Cretaceous stratigraphic group found in areas of Colorado, New Mexico, Utah, and Wyoming, in the Western United States.
The geology of Alberta encompasses parts of the Canadian Rockies and thick sedimentary sequences, bearing coal, oil and natural gas, atop complex Precambrian crystalline basement rock.
References
↑ Spieker, E.M., and Reeside, J.B., Jr., 1925, Cretaceous and Tertiary formations of the Wasatch Plateau, Utah: Geological Society of America Bulletin, v. 36, no. 3, p. 435-454.
1 2 Weiss, M.P., Witkind, I.J. and Cashion, W.B., 2003. Geologic Map of the Price 30ʹ X 60ʹ Quadrangle, Carbon, Duchesne, Uintah, Utah, and Wasatch Counties, Utah. Utah Geological Survey Map 198DM.
1 2 Chan, M.A., Newman, S.L. and May, F.E., 1991. Deltaic and shelf deposits in the Cretaceous Blackhawk Formation and Mancos Shale. Grand County, Utah: Utah Geological Survey, Miscellaneous Publication 91-6.
1 2 3 4 5 Balsley, J.K., 1983. Cretaceous Wave-Dominated Delta Systems: Book Cliffs, East Central Utah. Oklahoma City Geological Society, Short Course. 219 p.
1 2 3 Parker, L.R., 1976. The paleoecology of the fluvial coal-forming swamps and associated floodplain environments in the Blackhawk Formation (upper Cretaceous) of Central Utah. Bigham Young University Geology Studies v. 22, pt. 3, pp. 99-116.
1 2 3 Tidwell, W.D., Britt, B.B. and Tidwell, L.S., 2007. A review of the Cretaceous floras of east-central Utah and western Colorado. In Willis, G.C., Hylland, M.D, Clark, D,L, and Chidsey, T.C., editors, Central Utah: Diverse Geology of a Dynamic Landscape, Utah Geological Association Publication 36, pp/ 467-482.
1 2 3 Parker, L.R., and Balsley, J.K., 1989, Coal mines as localities for studying dinosaur trace fossils, in Gillette, D.D., and Lockley, M.G., editors, Dinosaur tracks and traces: New York, Cambridge University Press, p. 353–359.
1 2 3 4 Carpenter, K., 1992, Behaviour of hadrosaurs as interpreted from footprints in the “Mesaverde” Group (Campanian) of Colorado, Utah, and Wyoming: Contributions to Geology, University of Wyoming, v. 29, p. 81–96.
↑ Strevell, CN. 1932. Dinosauropodes. Self-published, Salt Lake City, 16 p.
↑ Lockley, M.; Harris, J.D.; and Mitchell, L. 2008. "A global overview of pterosaur ichnology: tracksite distribution in space and time." Zitteliana. B28. p.187-198
1 2 some specimens are on display at the Prehistroic Museum in Price Utah.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
United States 
