Search

Thin, radiating, darker bands occur on pyritic internal moulds of the Early Jurassic ammonites Oxynoticeras and Cheltonia from Bishop's Cleeve, Gloucestershire. They closely resemble true colour patterns preserved in Early Jurassic Calliphylloceras from Kutch, India, and false colour patterns reported in Carboniferous and Triassic ammonoids. Up to five dark bands occur within the body chamber, suggesting that they do not represent serially repeated anatomical structures, but the same feature repeatedly formed during growth. Dark bands are interpreted as traces of black bands deposited on the inside of the shell at the aperture during pauses in growth. The angles between dark bands and between septa correlate strongly in Cheltonia, suggesting that pauses in growth coincided with septal secretion during the chamber formation cycle. There are, however, no other indications that growth was episodic in either genus. [ABSTRACT FROM AUTHOR]

Two types of ‘pseudobreccia’, one with grey and the other with brown mottle fabrics, occur in shoaling-upward cycles of the Urswick Limestone Formation of Asbian (Late Dinantian, Carboniferous) age in the southern Lake District, UK. The grey mottle pseudobreccia occurs in cycle-base packstones and developed after backfilling and abandonment of Thalassinoides burrow systems. Burrow infills consist of a fine to coarse crystalline microspar that has dull brown to moderate orange colours under cathodoluminescence. Mottling formed when an early diagenetic ‘aerobic decay clock’ operating on buried organic material was stopped, and sediment entered the sulphate reduction zone. This probably occurred during progradation of grainstone shoal facies, after which there was initial exposure to meteoric water. Microspar calcites then formed rapidly as a result of aragonite stabilization. The precipitation of the main meteoric cements and aragonite bioclast dissolution post-date this stabilisation event. The brown mottle pseudobreccia fabrics are intimately associated with rhizocretions and calcrete, which developed beneath palaeokarstic surfaces capping cycle-top grainstones and post-date all depositional fabrics, although they may also follow primary depositional heterogeneities such as burrows. They consist of coarse, inclusion-rich, microspar calcites that are always very dull to non-luminescent under cathodoluminescence, sometimes with some thin bright zones. These are interpreted as capillary rise and pedogenic calcrete precipitates. The δ18O values (−5‰ to −8‰, PDB) and the δ13C values (+2‰ to −3‰, PDB) of the ‘pseudobreccias’ are lower than the estimated δ18O values (−3‰ to −1‰ PDB) and δ13C values of (+2‰ to +4‰ PDB) of normal marine calcite precipitated from Late Dinantian sea water, reflecting the influence of meteoric waters and the input of organic carbon. [ABSTRACT FROM AUTHOR]

Presents a study that analyzed the fossils of acritarchs and prasinophyte algae from the Upper Bringewood, Lower Leintwardine, Upper Leintwardine and Lower Whitcliffe formations of the Ludlow type area and its surrounding regions in England. Taxa propositions for the organisms; Review of previous biostratigraphical schemes for the specimens; Suggestions on the possibility of using certain biozonal indicators.

We have in Cornwall Rocks of that grandeur, remarkable shape and surprising position, as can leave us in no doubt but that they must have been the Deities of people addicted so much to the superstition of worshipping Rocks (Revd W. Borlase 1973 [1754]: 171). [ABSTRACT FROM AUTHOR]

The geology of Portreath preserved both in the natural outcrop and as building stones is assessed as a potential resource for visiting educational groups. Portreath is a former mining port, its expansion and historical development being closely associated with local and regional geology. A fieldwork programme and complementary literature search revealed that this location contains a wide range of accessible rock types suitable for student analysis. [ABSTRACT FROM AUTHOR]

A classic British geological locality revisited. [ABSTRACT FROM AUTHOR]

The article presents a study about the Jurassic limestone grassland at the old stone quarries in Collyweston, Northamptonshire. It examines the geological formation and soil in the area and the role it plays on the vegetation occupying the area, including two grasses, Zerna erecta and Brachypodium pinnatum. The relative abundance of commoner plants in the area is discussed. A chart is also presented which shows the plant species available at Barnack and Collyweston and their approximate frequencies.

The article discusses the examination on the distribution of plant associations and their relation to the geological formations in several areas in Newbury and Berkshire in England. These formations are based on the chalk syncline which extends from the scarp of the north Hampshire and Wiltshire on the south locations of England. The primitive vegetation in several areas is examined which includes the formation of alluvium of the Kennet valley, terraces of river gravel, the tertiary sands and clays, and the plateau gravels. The residential settlements on the borders of the uninhabited heath is also discussed.

Or, how the‘Dudley Bug’ escapes from a town Museum in the English Midlands and tries to find its way back on to Dudley's Coat of Arms... [ABSTRACT FROM AUTHOR]

Recounts the existence of a Welsh slate quarry in the ridges of Brendon Hills on the northern slopes of Exmoor, England and describes the local geology then and thereafter. Sandstones, siltstones and slates of the Ilfracombe Beds; Rock cleavage; History of the Welsh enterprise.

Analyzes the structure of the Bude Formation in south-west England. Composition and features of the Bude Formation; Occurrence of deposition in a Westphalian lake with occasional connections; Growth of a series of subsea fan turbidite-systems across the basin floor on the northern, passive margin of a foreland basin.