Stage 10 of the Cambrian is the still unnamed third and final stage of the

Furongian The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from to million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into thre ...

series. It follows the

Jiangshanian The Jiangshanian is the middle stage of the Furongian series. It follows the Paibian Stage and is succeeded by the still unnamed Stage 10 of the Cambrian. The base is defined as the first appearance of the trilobite '' Agnostotes orientalis'' whi ...

and precedes the Ordovician

Tremadocian The Tremadocian is the lowest stage of Ordovician. Together with the later Floian Stage it forms the Lower Ordovician Epoch. The Tremadocian lasted from to million years ago. The base of the Tremadocian is defined as the first appearance of the ...

Stage. The proposed lower boundary is the first appearance of the trilobite ''

Lotagnostus americanus ''Lotagnostus'' is a genus of very small trilobites in the order Agnostida, which lived on the outer continental shelves worldwide, during the late Upper Cambrian. It was described by Whitehouse in 1936, and the type species is ''Lotagnostus tris ...

'' around million years ago, but other fossils are also being discussed ( see below). The upper boundary is defined as the appearance of the

conodont Conodonts ( Greek ''kōnos'', " cone", + ''odont'', " tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, w ...

Iapetognathus fluctivagus ''Iapetognathus fluctivagus'' is a species of denticulate cordylodan conodonts belonging to the genus ''Iapetognathus''. It existed during the Tremadocian Age ( million years ago) of the Ordovician. It is an important index fossil in biostratig ...

'' which marks the beginning of the

and is radiometrically dated as million years ago.

Naming

The 10th stage of the Cambrian has not been formally named by the

ICS ICS may refer to: Computing * Image Cytometry Standard, a digital multidimensional image file format used in life sciences microscopy * Industrial control system, computer systems and networks used to control industrial plants and infrastructu ...

yet, although a number of

local names Local may refer to: Geography and transportation * Local (train), a train serving local traffic demand * Local, Missouri, a community in the United States * Local government, a form of public administration, usually the lowest tier of administrat ...

exist. Several authors favor the name "Lawsonian" after

Lawson Cove Lawson may refer to: Places Australia * Lawson, Australian Capital Territory, a suburb of Canberra * Lawson, New South Wales, a town in the Blue Mountains Canada * Lawson, Saskatchewan * Lawson Island, Nunavut United States * Lawson, Arkansas ...

, in the

Wah Wah Mountains The Wah Wah Mountains are a north-south trending range in west-central Utah, part of the larger Basin and Range Province. It is bounded by Pine Valley to the west, Wah Wah Valley to the east, the Escalante Desert to the south, and on trend with ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

. The lower part of the North American Skullrockian Stage corresponds roughly to the Cambrian Stage 10.

Stratotype

The

is still discussing which geological section and biostratigraphic marker will be used to define the base of the 10th Cambrian stage. Likely candidates for the section are still investigated. A first proposal was a section near Duibian,

Zhejiang Zhejiang ( or , ; , also romanized as Chekiang) is an eastern, coastal province of the People's Republic of China. Its capital and largest city is Hangzhou, and other notable cities include Ningbo and Wenzhou. Zhejiang is bordered by ...

province (China). Note recent publications favor

Steamboat Pass A steamboat is a boat that is propelled primarily by steam power, typically driving propellers or paddlewheels. Steamboats sometimes use the prefix designation SS, S.S. or S/S (for 'Screw Steamer') or PS (for 'Paddle Steamer'); however, thes ...

in the

House Range The House Range is a north-south trending mountain range in Millard County, of west-central Utah. The House Range was named in 1859 by James H. Simpson. It was named by Simpson because "...of its well-defined stratification and the resemblance ...

. If a conodont is used for the base the stage then many more sections would be likely candidates for the

GSSP A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted ...

, e.g. in Australia, Kazakhstan and Canada. Candidates for the biostratigraphic marker are the

first appearance In American comic books and other stories with a long history, first appearance refers to the first issue to feature a fictional character. These issues are often highly valued by collectors due to their rarity and iconic status. Reader interes ...

of a

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

species. The trilobite ''

'' was first suggested by the ICS, but has proven to be problematic. In 2006 another working group proposed the first appearance of ''

Cordylodus andresi ''Cordylodus'' is an extinct genus of conodonts in the family of Cordylodontidae. Use in stratigraphy It is suggested that ''Cordylodus andresi'' can be a marker of the Cambrian Stage 10. Distribution Fossils of ''Cordylodus'' have been f ...

''. Currently the first appearance of ''

Eoconodontus notchpeakensis ''Eoconodontus'' is an extinct genus of conodonts of the Late Cambrian. It is a two-elements (rounded and compressed) genus from the ''Proconodontus'' lineage. Use in stratigraphy It is suggested that ''Eoconodontus notchpeakensis'' can be a m ...

'' is favored by many authors because it is globally widespread and is independent of

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ...

(known from continental rise to peritidal environments). The ''

'' proposal would also incorporate a non-biostratigraphic marker to correlate the beginning of stage 10 globally. A carbon isotope excursion (the HERB-event) occurs in the lower part of the '' E. notchpeakensis'' range.

Subdivisions

Cambrian Stage 10 can be subdivided using different biostratigraphic zones. Several conodont zone and subzones can be distinguished. The same is true for trilobites.

References

{{Geological history, p, p, state=collapsed Cambrian geochronology Geological ages Cambrian Utah Furongian