scholarly journals IV. The lignite of bovey tracey

The lignite of Bovey Tracey, in Devon, was fully described by Oswald Heer and Pengelly in these ‘ Transactions,' and there is no need to repeat their description. The conclusion Heer came to, from the study of the fossil plants (except a single beetle there were no other fossils), was that the deposit “must be referred to the Lower Miocene division and to the Aquitanian stage of it,” or as we should now put it, the strata were Upper Oligocene or, perhaps, Lower Miocene. Heer also considered it to be equivalent to the Hamstead Beds of the Isle of Wight, which we now know are somewhat earlier than the Aquitanian and are of Middle Oligocene date. Doubt has since been thrown on these conclusions by Mr. Starkie Gardner, who considered that the flora collected by Heer and Pengelly is identical with that of the Bournemouth Beds (Middle Eocene). Mr. Gardner appears to have made no collections at Bovey, and in his Bournemouth collections (now in the Museum of Natural History) we can find nothing to justify this statement. Perhaps this extreme view is somewhat modified by later changes in the identification of some of the plants.

In 1863, Heer and Pengelly published in the ‘Phil. Trans.’ an account of these lignite-beds and their flora. Heer classed the lignite as Lower Miocene, considering it equivalent to the Aquitanian of Prance and to the Hamstead Beds of the Isle of Wight. These latter are now referred to the Middle Oligocene, and many of the other deposits called Lower Miocene in Heer’s day are now classed as Upper Oligocene. A statement by Mr. Starkie Gardner, that Heer’s Bovey plants are the same as those found in the Bournemouth Beds (Middle Eocene), has caused the Bovey Beds to be classed as Eocene in recent text-books and on recent maps of the Geological Survey, leaving a great gap in the geological record in Britain. Every division, from Upper Oligocene to Upper Miocene, was supposed to be missing.


Geosciences ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
Santiago Moliner-Aznar ◽  
Manuel Martín-Martín ◽  
Tomás Rodríguez-Estrella ◽  
Gregorio Romero-Sánchez

The Cenozoic Malaguide Basin from Sierra Espuña (Internal Betic Zone, S Spain) due to the quality of outcropping, areal representation, and continuity in the sedimentation can be considered a key-basin. In the last 30 years, a large number of studies with very different methodological approaches have been done in the area. Models indicate an evolution from passive margin to wedge-top basin from Late Cretaceous to Early Miocene. Sedimentation changes from limestone platforms with scarce terrigenous inputs, during the Paleocene to Early Oligocene, to the deep basin with huge supplies of turbidite sandstones and conglomerates during the Late Oligocene to Early Miocene. The area now appears structured as an antiformal stack with evidence of synsedimentary tectonics. The Cenozoic tectono-sedimentary basin evolution is related to three phases: (1) flexural tectonics during most of the Paleogene times to create the basin; (2) fault and fold compartmentation of the basin with the creation of structural highs and subsiding areas related to blind-fault-propagation folds, deforming the basin from south to north during Late Oligocene to Early Aquitanian times; (3) thin-skin thrusting tectonics when the basin began to be eroded during the Late Aquitanian-Burdigalian. In recent times some works on the geological heritage of the area have been performed trying to diffuse different geological aspects of the sector to the general public. A review of the studies performed and the revisiting of the area allow proposing different key-outcrops to follow the tectono-sedimentary evolution of the Cenozoic basin from this area. Eight sites of geological interest have been selected (Cretaceous-Cenozoic boundary, Paleocene Mula Fm, Lower Eocene Espuña-Valdelaparra Fms, Middle Eocene Malvariche-Cánovas Fms, Lowermost Oligocene As Fm, Upper Oligocene-Lower Aquitanian Bosque Fm, Upper Oligocene-Aquitanian Río Pliego Fm, Burdigalian El Niño Fm) and an evaluation has been performed to obtain four parameters: the scientific value, the educational and touristic potential, and the degradation risk. The firsts three parameters obtained values above 50 being considered of “high” or “very high” interest (“very high” in most of the cases). The last parameter shows always values below 50 indicating a “moderate” or “low” risk of degradation. The obtained values allow us considering the tectono-sedimentary evolution of this basin worthy of being proposed as a geological heritage.


2021 ◽  
Vol 118 (37) ◽  
pp. e2105956118
Author(s):  
Kenneth E. Campbell ◽  
Paul B. O’Sullivan ◽  
John G. Fleagle ◽  
Dorien de Vries ◽  
Erik R. Seiffert

The Santa Rosa fossil locality in eastern Perú produced the first Paleogene vertebrate fauna from the Amazon Basin, including the oldest known monkeys from South America. This diverse paleofauna was originally assigned an Eocene age based largely on the stage of evolution of the site’s caviomorph rodents and marsupials. Here, we present detrital zircon dates that indicate that the maximum composite age of Santa Rosa is 29.6 ± 0.08 Ma (Lower Oligocene), although several zircons from Santa Rosa date to the Upper Oligocene. The first appearance datum for Caviomorpha in South America is purported to be the CTA-27 site in the Contamana region of Perú, which is hypothesized to be ∼41 Ma (Middle Eocene) in age. However, the presence of the same caviomorph species and/or genera at both CTA-27 and at Santa Rosa is now difficult to reconcile with a >11-My age difference. To further test the Middle Eocene age estimate for CTA-27, we ran multiple Bayesian tip-dating analyses of Caviomorpha, treating the ages of all Paleogene species from Perú as unknown. These analyses produced mean age estimates for Santa Rosa that closely approximate the maximum 29.6 ± 0.08 Ma composite date provided by detrital zircons, but predict that CTA-27 is much younger than currently thought (∼30 Ma). We conclude that the ∼41 Ma age proposed for CTA-27 is incorrect, and that there are currently no compelling Eocene records of either rodents or primates in the known fossil record of South America.


1943 ◽  
Vol 80 (3) ◽  
pp. 107-110
Author(s):  
M. Avnimelech

Several years ago I wrote a number of papers on the results of my investigations in a synclinal area near Megiddo, south-east of Mount Carmel, which I called “ the syncline of Megiddo ”. In the thick Eocene series of this syncline two distinct horizons of Lower and Upper Lutetian have been recognized. Above the Lutetian beds some patches of transgressive Upper Oligocene are preserved. Unfortunately the publications were based on investigations of only the north-eastern border of the whole synclinal region, further field explorations having been made impossible by the riots in 1936−39. In the summer of 1942 I renewed my fieldwork, which has led to a discovery of an Upper Eocene transgression over a probable Middle Eocene series.


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