Early Late Cambrian Dendroid Graptolites from the northern Yukon

1976 ◽  
Author(s):  
W B N Berry ◽  
B S Norford
Keyword(s):  
Late Cambrian ◽  
Early Late

scholarly journals Reconstruction of the enigmatic Late Cambrian Climactichnites

1992 ◽  
Vol 6 ◽  
pp. 321-321 ◽  
Author(s):  
E.L. Yochelson ◽  
M. Parrish
Keyword(s):  
New York ◽  
Cross Section ◽  
Individual Variation ◽  
Short Distance ◽  
Loose Sand ◽  
Desiccation Cracks ◽  
Late Cambrian ◽  
Anterior Flap ◽  
Considerable Individual Variation ◽  
Early Late

Climactichnites Logan, 1860, is known only from its large trail up to 20 cm in width, a trace superficially resembling a rope ladder. Prominent lateral ridges are parallel throughout the length of the trail; they may be smooth and hemispherical in cross-section or crenulated, much like a pie crust. Between these ridges is a series of raised dune-like bars and furrows dug into the substrate. The bars and furrows show considerable individual variation between trails and also variation along a trail. Ovoid impressions are known which occur at the start of trails. The posterior of these impressions is well rounded; the anterior is triangular, and for a short distance from the impression, the trail is developed on only one side. One exceptionally preserved impression shows curved, closely spaced, fine lines parallel to the posterior.The trails are found only in sandstone, and where they are present, they are abundant. Slightly equivocable evidence indicates a Dresbachian (early Late Cambrian) age for the occurrences in New York, Missouri, and Wisconsin; trails in Ontario and Quebec are less certainly dated. Desiccation cracks and air escape hole suggest that the trail was fully exposed to the atmosphere.From this data, a large number of sketches were made to reconstruct an animal able to make such a trail. Each attempt produced new speculation on the morphology. In the final rendition, the animal is bilaterally symmetrical, broad and low. The integument is tough, and the sole bears a subcentral mouth anteriorward. Lateral flaps scraped and compressed damp sand to make the parallel ridges. The anterior was strongly musculated and thin. This anterior flap grasped the sediment, alternating on either side of the animal to pull the form forward when the lateral flaps were relaxed. Curved rows of cilia on the posterior moved loose sand into dunes between the furrows formed by the anterior flaps.This reconstruction is like that of no other animal known in the Vendian or the Phanerozoic.

scholarly journals Early Late Cambrian Trilobites OF Australo-Sinian Aspect From The Montagne Noire, Southern France

Palaeontology ◽  
2000 ◽  
Vol 43 (4) ◽  
pp. 599-632 ◽  
Author(s):  
John H. Shergold ◽  
Raimund FEIST ◽  
Daniel Vizcaino
Keyword(s):  
Southern France ◽  
Late Cambrian ◽  
Montagne Noire ◽  
Early Late

Biostratigraphic significance and paleogeographic implications of Cambrian fossils from a deep core, Warren County, Ohio

1994 ◽  
Vol 68 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Loren E. Babcock
Keyword(s):  
Trace Fossils ◽  
Inner Shelf ◽  
Middle Cambrian ◽  
Late Cambrian ◽  
Warren County ◽  
Eau Claire ◽  
Early Late

A deep core from Warren County, Ohio, has yielded numerous fossils of Cambrian age. The specimens, which are among the first recorded from Cambrian rocks of Ohio, suggest revisions in the inferred ages of the Eau Claire and Mount Simon Formations in the Cincinnati Arch region. Trilobites indicative of Dresbachian (late Middle Cambrian to early Late Cambrian) and possibly Franconian (Late Cambrian) age are present in the upper Eau Claire Formation. By implication, the underlying Mount Simon Formation must be of earlier Dresbachian age or perhaps older. Identified trilobites from the Eau Claire Formation seem to be characteristic of inner-shelf lithofacies of Laurentia. Other body fossils from the Eau Claire Formation include inarticulate brachiopods and a graptolite. Body fossils in the lower Knox Dolomite include trilobite sclerites and echinoderm ossicles. Trace fossils are present in both units.

Early Palaeozoic history of the upper Beardmore Glacier area: implications for a major Antarctic structural boundary within the Transantarctic Mountains

1989 ◽  
Vol 1 (3) ◽  
pp. 249-260 ◽  
Author(s):  
A.J. Rowell ◽  
Margaret N. Rees
Keyword(s):  
Volcanic Rocks ◽  
Glacier Area ◽  
Late Cambrian ◽  
History Of ◽  
Lower Palaeozoic ◽  
Transantarctic Mountains ◽  
Early Palaeozoic ◽  
Middle And Late Cambrian ◽  
Structural Boundary ◽  
Early Late

The central and western Transantarctic Mountains appear to be divided longitudinally by one or more terrane boundaries that separate two regions characterized by different Lower Palaeozoic successions. Re-examination of the upper Beardmore Glacier area and reinterpretation of its Early Palaeozoic stratigraphy emphasizes the strong similarity between it and the Byrd Group outcrops in the area between the Byrd and Nimrod glaciers. This similarity demonstrates that for several hundred kilometres the Cambrian succession of an inboard region is largely devoid of volcanic rocks but includes fossiliferous Lower Cambrian platformal limestones that are overlain unconformably by coarse basin-fill deposits. The latter probably include beds of Middle and perhaps early Late Cambrian age that were themselves deformed prior to the Devonian. Erratic blocks indicate that comparable successions may have been developed as far west as the Whichaway Nunataks. The inferred geological history of this part of the continental margin, which is commonly regarded as autochthonous, stands in contrast to that of more outboard regions where thick volcanic sequences occur in expanded stratigraphic sections that include shallow-marine Middle and Late Cambrian deposits. We consider that these regions, predominantly the Queen Maud and Theil mountains and the Neptune Range of the Pensacola Mountains, constitute one or more displaced crustal blocks. The boundary between them and the inboard sequence adjacent to the craton is probably a series of large strike-slip faults that may have been initiated during the Early Palaeozoic and have been active episodically since then.

scholarly journals Cambrian - Middle Ordovician stratigraphy of the Adams Gletscher region, south-west Peary Land, North Greenland

1979 ◽  
Vol 88 ◽  
pp. 29-39
Author(s):  
J.S Peel
Keyword(s):  
Substantial Part ◽  
Middle Cambrian ◽  
Middle Ordovician ◽  
Late Cambrian ◽  
South West ◽  
Lower Ordovician ◽  
Field Notes ◽  
Early Late ◽  
North Greenland ◽  
Cambrian System

Previous geological descriptions of the Adams Gletscher region (fig. 9) have been given by J. C. Troelsen (unpublished field notes in GGU) and Dawes (1976) - the latter based on a three day reconnaissance during 1975. The sequence contains a much fuller record of the Cambrian system than is present in the geologicaIly better described area near Jørgen Brønlund Fjord to the east (Christie & Peel, 1977; Jepsen, 1971), where only Lower Cambrian strata are present. A sample with trilobites collected by Dawes established the occurrence of Middle Cambrian rocks near Adams Gletscher (Peel in Dawes, 1976), but it would now appear that a substantial part of the sequence is of this age. In addition, the location in 1978 of early Late Cambrian trilobites near the base of a 900 m thick unit overlain by the Wandel Valley Formation of Early-Middle Ordovician age, suggests that the upper sub-division of the Cambrian is also well represented. An unconformity of regional extent separates the Cambrian from the overlying Wandel Valley Formation. This formation maintains the same generallithology at Adams Gletscher as that described by Christie & Peel (1977) to the east, although a tentative lithologicallink to the late Lower Ordovician of western North Greenland is established.

Middle to Upper Cambrian linguliformean brachiopods from the Deadwood Formation of subsurface Alberta and Saskatchewan, Canada

2003 ◽  
Vol 77 (2) ◽  
pp. 201-211 ◽  
Author(s):  
Sean P. Robson ◽  
Godfrey S. Nowlan ◽  
Brian R. Pratt
Keyword(s):  
New Species ◽  
Valid Species ◽  
Upper Cambrian ◽  
Late Cambrian ◽  
Two New Species ◽  
Brachiopod Fauna ◽  
Early Late

Limestone beds intercalated within a succession of sandstones, siltstones, and shales of the subsurface Deadwood Formation, cored in two wells in Alberta and Saskatchewan, yielded twelve species assigned to eight genera of organophosphatic brachiopods (Subphylum Linguliformea). The nine species recovered from the Alberta well are Marjuman (late Middle to early Late Cambrian) in age. Three of these species, Neotreta davidi Popov, Berg-Madsen, and Holmer, 1994; Picnotreta debilis Henderson and MacKinnon, 1981; and Stilpnotreta magna Henderson and MacKinnon, 1981, are associated with the Mindyallan (early Late Cambrian) of Queensland, and are previously unknown from Laurentia. This brachiopod fauna occurs with a diverse fauna of paraconodont species. The Saskatchewan well yielded three species of Linnarssonella, belonging to the upper Steptoean to the lower Sunwaptan (middle Late Cambrian). One new subfamily, Neotretinae, is erected, and two new species, Rhondellina albertensis, and Linnarssonella tubicula are described. Linnarssonella elongata Bell, 1941, is reinstated as a valid species. This fauna occurs with a diverse fauna of paraconodont species and is overlain, 226 feet higher, by conodonts of the Early Sunwaptan Proconodontus Zone.

Sign in / Sign up

Export Citation Format

Share Document