| Illtyd Formation | |
|---|---|
| Stratigraphic range: Cambrian | |
| Type | Formation |
| Underlies | Slats Creek Fm |
| Location | |
| Region | Yukon |
| Country | Canada |
The Illtyd Formation is an up to 1000-m thick geologic formation in Yukon. It preserves fossils dating back to the Dyerian subdivision of the Cambrian period, which spans the Stage 3 / Stage 4 boundary; it's considered to belong to the mid-upper Bonnia-Olenellus trilobite Zone. Top of the unit corresponds, more or less, to the top of Stage 4. [1] [2] These fossils include Lower Cambrian trilobites'. [3]
The type section is in the Wernecke Mtns; it corps out also in and to the S/SW of the Rochardson Moutnars. It possibly corresponds to the Sekwi Fm in the Macxkenzie mtns. [1]
Lowermost of the Palaeozoic strata west of the Richardson Mountains, angular unconformity at base, overlying various Precambrian strata. Silty limestones and massive dolomites. In places rhythmically bedded. Colour: Tan, brownish grey muds; sandier layers orange. Upper layers include oolites and oncolites. Trace fossils include burrows and 'worm trails'. In some places unit is massively faulted and altered / weathered, approaching marble grade metamorphism near faults. [1]
Olenellus is an extinct genus of redlichiid trilobites, with species of average size. It lived during the Botomian and Toyonian stages (Olenellus-zone), 522 to 510 million years ago, in what is currently North-America, part of the palaeocontinent Laurentia.
Laudonia is an extinct genus of trilobites that lived during the early part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. There are currently two named species assigned to it.
Elliptocephala is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived from the later part of the Tommotian to the upper Botomian. Elliptocephala can easily be confused with Ellipsocephalus, a trilobite genus of the Ptychopariida order.
The Cathedral Formation is a stratigraphic unit in the southern Canadian Rockies of Alberta and British Columbia, on the western edge of the Western Canada Sedimentary Basin. It is a thick sequence of carbonate rocks of Middle Cambrian age. It was named for Cathedral Mountain in Yoho National Park by Charles Doolittle Walcott, the discoverer of the Burgess shale fossils.
The Tonto Group is a name for an assemblage of related sedimentary strata, collectively known by geologists as a Group, that comprises the basal sequence Paleozoic strata exposed in the sides of the Grand Canyon. As currently defined, the Tonto groups consists of the Sixtymile Formation, Tapeats Sandstone, Bright Angel Shale, Muav Limestone, and Frenchman Mountain Dolostone. Historically, it included only the Tapeats Sandstone, Bright Angel Shale, and Muav Limestone. Because these units are defined by lithology and three of them interfinger and intergrade laterally, they lack the simple layer cake geology as they are typically portrayed as having and geological mapping of them is complicated.
Except where underlain by the Sixtymile Formation, the Tapeats Sandstone is the Cambrian geologic formation that is the basal geologic unit of the Tonto Group. Typically, it is also the basal geologic formation of the Phanerozoic strata exposed in the Grand Canyon, Arizona, and parts of northern Arizona, central Arizona, southeast California, southern Nevada, and southeast Utah. The Tapeats Sandstone is about 70 m (230 ft) thick, at its maximum. The lower and middle sandstone beds of the Tapeats Sandstone are well-cemented, resistant to erosion, and form brownish, vertical cliffs that rise above the underlying Precambrian strata outcropping within Granite Gorge. They form the edge of the Tonto Platform. The upper beds of the Tapeats Sandstone form the surface of the Tonto Platform. The overlying soft shales and siltstones of the Bright Angel Shale underlie drab-greenish slopes that rise from the Tonto Platform to cliffs formed by limestones of the Muav Limestone and dolomites of the Frenchman Mountain Dolostone.
Bristolia is an extinct genus of trilobite, fossil marine arthropods, with eight or more small to average size species. It is common in and limited to the Lower Cambrian shelf deposits across the southwestern US, which constitutes part of the former paleocontinent of Laurentia.
Bolbolenellus is an extinct genus of trilobites, fossil marine arthropods, with five species attributed to it currently. It can be easily distinguished from all other trilobites by the combination of the absence of dorsal sutures in the head shield like all Olenellina, and a distinctly bulbous frontal lobe (L4) of the raised axial area in the head called glabella. The species lived at the end of the Lower Cambrian.
The Shackleton Limestone is a Cambrian limestone formation of the Byrd Group of Antarctica. The age of the formation is established to be Cambrian Stage 3, dated at ranging from 520 to 516 Ma. This period correlates with the End-Botomian mass extinction. Fossils of trilobites and Marocella mira and Dailyatia have been found in the formation, named after Ernest Shackleton, who led a failed expedition into Antarctica. At time of deposition, the Antarctic Plate has been established to be just south of the equator as part of the supercontinent Pannotia, contrasting with its present position at 82 degrees southern latitude.
The Bright Angel Shale is one of five geological formations that comprise the Cambrian Tonto Group. It and the other formations of the Tonto Group outcrop in the Grand Canyon, Arizona, and parts of northern Arizona, central Arizona, southeast California, southern Nevada, and southeast Utah. The Bright Angel Shale consists of locally fossiliferous, green and red-brown, micaceous, fissile shale (mudstone) and siltstone with local, thicker beds of brown to tan sandstone and limestone. It ranges in thickness from 57 to 450 ft. Typically, its thin-bedded shales and sandstones are interbedded in cm-scale cycles. They also exhibit abundant sedimentary structures that include current, oscillation, and interference ripples. The Bright Angel Shale also gradually grades downward into the underlying Tapeats Sandstone. It also complexly interfingers with the overlying Muav Limestone. These characters make the upper and lower contacts of the Bright Angel Shale often difficult to define. Typically, its thin-bedded shales and sandstones erode into green and red-brown slopes that rise from the Tonto Platform up to cliffs formed by limestones of the overlying Muav Limestone and dolomites of the Frenchman Mountain Dolostone.
The Kinzers Formation is a geologic formation in Pennsylvania. It preserves fossils dating back to the Cambrian Period.
The Gog Group is a stratigraphic unit in the Western Canada Sedimentary Basin. It is present in the eastern and western main ranges of the Canadian Rockies in Alberta and British Columbia. It was named by C.F. Deiss in 1940 after Gog Lake near its type locality at Wonder Pass near Mount Assiniboine.
The Survey Peak Formation is a stratigraphic unit of latest Cambrian to earliest Ordovician age. It is present on the western edge of the Western Canada Sedimentary Basin in the Canadian Rockies of Alberta and British Columbia. It was named for Survey Peak near Mount Erasmus in Banff National Park by J.D. Aitken and B.S. Norford in 1967. The Survey Peak Formation is fossiliferous and includes remains of trilobites and other marine invertebrates, as well as conodonts, stromatolites, and thrombolites.
The Mount Whyte Formation is a stratigraphic unit that is present on the western edge of the Western Canada Sedimentary Basin in the southern Canadian Rockies and the adjacent southwestern Alberta plains. It was deposited during Middle Cambrian time and consists of shale interbedded with other siliciclastic rock types and limestones. It was named for Mount Whyte in Banff National Park by Charles Doolittle Walcott, the discoverer of the Burgess shale fossils, and it includes several genera of fossil trilobites.
The Miette Group is an assemblage of metamorphosed sedimentary rocks of latest Precambrian (Neoproterozoic) age. It is present in the Canadian Cordillera from the Lake Louise area of Alberta to the Yukon. The Miette rocks include Ediacaran fossils, stromatolites, and trace fossils.
One of the major depositional strata in the Himalaya is the Lesser Himalayan Strata from the Paleozoic to Mesozoic eras. It had a quite different marine succession during the Paleozoic, as most parts of it are sparsely fossiliferous or even devoid of any well-defined fossils. Moreover, it consists of many varied lithofacies, making correlation work more difficult. This article describes the major formations of the Paleozoic – Mesozoic Lesser Himalayan Strata, including the Tal Formation, Gondwana Strata, Singtali Formation and Subathu Formation.
The Random Formation is a rock unit in Newfoundland dating to the early Cambrian period, dominated by tidal quartz arenites deposited in a near-shore environment, but also incorporating intertidal and open-shelf deposits, including glauconitic and mud-cracked mudstones, and red channel sandstones. It was deposited quickly and is approximately 175 m (574 ft) thick. The Blue Pinion Formation was originally recognized as a separate formation, but is now interpreted as an expression of the Random Formation.
The Vampire Formation is a formation of delta-front siliciclastics deposited in the early Cambrian. The upper unit is trilobitic Cambrian. Some authors place the underlying Ingta formation at least partially in the Cambrian; in places it overlies the sub-Cambrian unconformity.
William Harold Fritz was a geologist who worked for the Geological Survey of Canada. He is known for his work in stratigraphy and on olenelloid trilobites.
The geology of the Ellsworth Mountains, Antarctica, is a rock record of continuous deposition that occurred from the Cambrian to the Permian periods, with basic igneous volcanism and uplift occurring during the Middle to Late Cambrian epochs, deformation occurring in the Late Permian period or early Mesozoic era, and glacier formation occurring in the Cretaceous period and Cenozoic era. The Ellsworth Mountains are located within West Antarctica at 79°S, 85°W. In general, it is made up of mostly rugged and angular peaks such as the Vinson Massif, the highest mountain in Antarctica.
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