The blue lias of the devon and dorset coasts

Lang, W. D.

doi:10.1016/s0016-7878(24)80032-9

Cited by 55 publications

(28 citation statements)

References 8 publications

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“…1B), approximately 195 million years old, was collected from Bed 32 of the Blue Lias Formation (early Jurassic, Lower Sinemurian) at Lyme Regis, Dorset (UK) (38). The Blue Lias Formation consists of decimeterscale cyclical alternations of fossiliferous mudstone and tabular or nodular argillaceous limestones (38).…”

Section: Methodsmentioning

confidence: 99%

Direct chemical evidence for eumelanin pigment from the Jurassic period

Glass

Ito

Wilby

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

172

168

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Melanin is a ubiquitous biological pigment found in bacteria, fungi, plants, and animals. It has a diverse range of ecological and biochemical functions, including display, evasion, photoprotection, detoxification, and metal scavenging. To date, evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. Here, we apply direct chemical techniques to categorically demonstrate the preservation of eumelanin in two >160 Ma Jurassic cephalopod ink sacs and to confirm its chemical similarity to the ink of the modern cephalopod, Sepia officinalis. Identification and characterization of degradation-resistant melanin may provide insights into its diverse roles in ancient organisms.

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Section: Methodsmentioning

confidence: 99%

Direct chemical evidence for eumelanin pigment from the Jurassic period

Glass

Ito

Wilby

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

172

168

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“…Lateral thickness variations of the Pre-planorbis Beds are probably partly due to the diachronous appearance of P. planorbis (Hodges, 1994). At Pinhay Bay they are 2.7 m thick (Lang, 1924).…”

Section: Stratigraphymentioning

confidence: 96%

“…The first Jurassic ammonite Psiloceras planorbis (J. de C. Sowerby) appears some distance above the base of the Blue Lias (Hodges, 1994), with the result that basal beds of this unit are known as the Pre-planorbis Beds, or sometimes the Ostrea Beds due to the abundance of the oyster Liostrea hisingeri (Nilsson) at this level (Lang, 1924). Lateral thickness variations of the Pre-planorbis Beds are probably partly due to the diachronous appearance of P. planorbis (Hodges, 1994).…”

Section: Stratigraphymentioning

confidence: 99%

“…Sections 2 to 5 consist of a discontinuous series of cliff exposures, whereas section 6 is seen on the foreshore immediately to the west of Seven Rocks Point. Lang's (1924) bed numbering scheme for the Blue Lias is readily applicable and is utilized here. Hallam (1960a) provided bed numbers for the White Lias in section 1, but such is the rapid lateral variation that they are difficult to apply in the other sections.…”

Section: Study Techniquesmentioning

confidence: 99%

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Sedimentology of the Triassic-Jurassic boundary beds in Pinhay Bay (Devon, SW England)

Wignall

2001

Proceedings of the Geologists' Association

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in Pinhay Bay (SE Devon) of the White Lias (Langport Member of the Lilstock Formation) and basal Blue Lias reveal rapidly changing palaeoenvironments during the Triassic-Jurassic (T-J) boundary interval. During deposition of the topmost White Lias a soft seafloor of micritic mudstone was lithified and bored. The resultant hardground was locally eroded, probably in a shallow marine setting, to form a spectacular intraformational conglomerate that was itself lithified. Brief subaerial emergence then followed and produced a fissured and pitted top surface to the White Lias. The regression was short lived and rapid transgression at the base of the Blue Lias established organic-rich shale deposition with a small framboidal pyrite population and low Th/U ratios indicative of a stable, sulphidic lower water column (euxinic conditions). The White Lias/Blue Lias contact thus records a short duration, high amplitude relative sea-level change. This sea-level oscillation has also been postulated for other T-J boundary sections in Europe, although the failure to identify it in regional-scale sequence stratigraphic studies is probably due to its brief duration. Deposition of the basal beds of the Blue Lias was marked by a discrete phase of syn-sedimentary folding and small growth fault activity that may record a regional pulse of extensional tectonic activity.

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“…1) This section is based on the work of Lang (1924) and his bed numbers are used. The base of the section, bed HI, is marked by the Paper Shales.…”

Section: D Section At Lymementioning

confidence: 99%

The base of the Jurassic System: new data on the first appearance of Psiloceras planorbis in southwest Britain

Hodges

1994

Geol. Mag.

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Recent collecting in the Lower Lias of localities at StAudrie's Bay, north Somerset, Sedbury Cliff, Gloucester and Lavernock Point, South Glamorgan has yielded Psiloceras planorbis (J. de C. Sowerby) in beds considered by some to be of Rhaetian, Triassic age. These are the earliest records of this ammonite to date in southwest Britain. Evidence is provided of a major facies change at the top of the pre-planorbis beds followed by the diachronous first occurrence of Psiloceras planorbis. These new data have implications for the use of earliest occurrence of Psiloceras planorbis as a chronostratigraphic marker in defining the base of the Jurassic System, and for the definition of the base of the Hettangian Stage in the recently proposed candidate Global Stratotype Section at St Audrie's Bay.

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The blue lias of the devon and dorset coasts

Cited by 55 publications

References 8 publications

Direct chemical evidence for eumelanin pigment from the Jurassic period

Direct chemical evidence for eumelanin pigment from the Jurassic period

Sedimentology of the Triassic-Jurassic boundary beds in Pinhay Bay (Devon, SW England)

The base of the Jurassic System: new data on the first appearance of Psiloceras planorbis in southwest Britain

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