scholarly journals X. The fossil flora of the culm measures of North-west Devon, and the palœobotanical evidence with regard to the age of the beds

1905 ◽  
Vol 197 (225-238) ◽  
pp. 291-325 ◽  
Keyword(s):  
Carbonaceous Material ◽  
Physical Structure ◽  
Fossil Flora ◽  
The South ◽  
Lower Carboniferous ◽  
Red Sandstone ◽  
North West ◽  
The North ◽  
South Wales ◽  
Plant Remains

The deposits of Upper Palæozoic age in the south-west of England differ remarkably in their general characters from those developed on the north side of the Bristol Channel. This conclusion applies not only to the Devonian rocks, but also to the succeeding Carboniferous series. In South Wales and Monmouth, the Devonian beds are of the Old Red Sandstone type, whereas, the Devonian succession of North Devon exhibits a marked, though not an entire change, in both petrological characters and palæontological facies; a change which becomes even more marked in the series of limestones, volcanic, and detrital deposits developed in the southern portion of that county. The South Wales coalfield, the largest and most important productive measures in this country, consists of a sequence of coal-bearing strata, resting upon beds of Lower Carboniferous age, for the most part similar in character to those occurring in our other English coalfields. In Devonshire, and in portions of the neighbouring counties of Somerset and Cornwall, a Carboniferous basin of considerable size is developed, occupying more than 1,200 square miles. In many important respects these rocks again differ somewhat markedly from their equivalents in South Wales. They form a succession of deposits of a somewhat abnormal type; being composed of sediments of extremely varied nature and origin, both detrital and organic. They are especially characterised by a general absence of carbonaceous material of any economic importance. These Carboniferous rocks are spoken of as the Culm Measures, a name first applied to them by Sedgwick and Murchison in 1837. These authors in their classic memoir, published in 1840, gave the first accurate description of the physical structure of the beds, and proved conclusively their Carboniferous age. It may be pointed out, however, that De la Beche, in 1834, was the first to indicate the Upper Carboniferous age of that portion of the Culm Measures which forms the subject of this memoir; his conclusion being based on plant remains identified by Professor Lindley. De la Beche also added considerably to our knowledge of the Culm Measures in his ‘Report on the Geology of Cornwall and Devon,’ published in 1839. Since then, John Phillips, Holl, T. M. Hall, and others, and, in more recent times, Messrs. Hinde and Fox, and Mr. Ussher, have all contributed important information on this subject.

scholarly journals VIII. On the fossil flora of the forest of Dean Coalfield (Gloucestershire), and the relationships of the Coalfields of the West of England and South Wales

1912 ◽  
Vol 202 (282-293) ◽  
pp. 233-281 ◽  
Keyword(s):  
Great Basin ◽  
Point Of View ◽  
Fossil Flora ◽  
The South ◽  
The West ◽  
North West ◽  
The North ◽  
South Wales ◽  
Below Ground ◽  
Coal Measures

The Forest of Dean lies in a somewhat out-of-the-way corner of Gloucestershire, West of the Severn, and is bounded on the North-west by Herefordshire, and on the West and South by Monmouthshire and the Wye. The nearest coalfield is to the North, where a small area of Upper Carboniferous rocks occurs at Newent, also in Gloucestershire. The Bristol and Badstock coalfields lie some little distance to the South, and still further to the West is the great basin of South Wales. The Forest of Dean is remarkable for the simplicity of the structure of the Carboniferous area. As is well known, the basin is the most symmetrical in England, the beds, very little disturbed by faulting or folding, having, for the most part, a very regular outcrop. From the mining point of view, the entire absence of fire-damp and the consequent use of naked lights below ground, as is also the case in the Badstock coalfield, is remarkable. The Coal Measures, which occupy an area of about 16,700 acres, overlie beds which have long been spoken of as Millstone Grits, and these, with the Carboniferous Lime­-stone, form the elevated rim of the field, except for a short distance in the South-east, where the Coal Measures overstep both the so-called Millstone Grits and the Carboniferous Limestone (see p. 269). The latter has a much less regular distribution than the “Millstone Grits,” and a considerable development of the Limestone series is found to the North and West of the Forest, and this is continuous with a long tongue of Lower Carboniferous stretching South to Chepstow, and then South-west in the direction of Newport.

scholarly journals VI.—On the Old Red Sandstone and Carboniferous Rocks of the North—East of the Island of Arran

1896 ◽  
Vol 3 (5) ◽  
pp. 222-227
Author(s):  
James Neilson
Keyword(s):  
Fossil Flora ◽  
The West ◽  
Geological Society ◽  
Red Sandstone ◽  
North East ◽  
The North ◽  
Plant Remains ◽  
Sandy Shale ◽  
Marine Fossils ◽  
Carboniferous Limestone

In the Transactions of the Edinburgh Geological Society (vol. v, p. 316) will be found a notice of a section at Lochrim Burn, a quarter of a mile south of Corrie, where is exposed a bed of red sandy shale containing marine fossils. The catalogue contains fifteen species (certified by Mr. John Young, LL.D.), and every one of these is common in the Carboniferous Limestone series of the West of Scotland. This bed is overlain by another bed containing abundant plant-remains, of which a list of seven species is given. The Rev. D. Landsborough, of Kilmarnock, found here another, viz. Carpolithes sulcatus, L. and H. (“Fossil Flora,” pl. ccxx), which Mr. Kidston considers to be characteristic of the Calciferous Sandstone series. It seems to me, however, that the evidence is rather in favour of these beds belonging to the Limestone series. Then, as already noted, there are the fireclays, of which I have observed several distinct beds along the Corrie shore. There is also a bed of fireclay in the old quarry behind Corrie Hotel (within 100 feet of the Productus giganteus limestone); this overlies a bed of fine white sandstone. Fireclays also occur in the gap between the northern and the great eastern cliff.

II.—A Note on Fossil Plants from the Carboniferous Limestone of Chepstow

1907 ◽  
Vol 4 (1) ◽  
pp. 4-5 ◽  
Author(s):  
E. A. Newell Arber
Keyword(s):  
Trinity College ◽  
Left Bank ◽  
Fossil Plants ◽  
Lower Carboniferous ◽  
Red Sandstone ◽  
The North ◽  
Plant Remains ◽  
Sandy Shale ◽  
Carboniferous Limestone ◽  
Lime Stone

The occurrence of plant-remains in the Lower Carboniferous rocks of England is so rare that the recent discovery of impressions in beds belonging to that series at Chepstow, by my friend and pupil Mr. M. P. Price, B.A., of Trinity College, Cambridge, is worthy of record. Mr. Price has obtained several examples of a Sphenopterid frond and other plant fragments from a bed of sandy shale of about 4 feet in thickness, lying between a red sandstone below and lime-stone beds above, in one of the Pen Moel quarries on the left bank of the Wye, immediately to the north of Chepstow. This locality is mentioned in Dr. Vaughan's recent paper on the palæontological sequence in the Carboniferous Limestone of the Bristol area. That author informs me that he refers the beds in question to the lower portion of the Seminula-zone (S1 of his classification) on the evidence of the fauna.

The Chambered Barrow in Parc Le Breos Cwm, S. Wales

1937 ◽  
Vol 3 (1-2) ◽  
pp. 71-86 ◽  
Author(s):  
Glyn Daniel
Keyword(s):  
The South ◽  
The West ◽  
Valley Bottom ◽  
North West ◽  
The North ◽  
South Wales ◽  
The Subject ◽  
G 11 ◽  
Happy Valley ◽  
Small Valley

Parc Le Breos House stands in the south and centre of the Gower peninsula in West Glamorgan, about a mile north-west of Parkmill and a mile north of Penmaen, two small villages on the main road from Swansea westwards to Port Eynon and Rhossili. In the extensive woods surrounding the house is a small valley leading from Llethrid in the north to Parkmill in the south, and variously known as Parc le Breos Cwm, Parc Cwm, Green Cwm, and Happy Valley. A rough track leads up this valley from Parkmill to Green Cwm cottage, and, immediately to the west of this track and a little over half-a-mile north-west of Parkmill is the chambered barrow which forms the subject of this paper. Iron railings run round the greater part of the barrow, and inside these railings the barrow is covered with a heavy growth of trees. The sides of the Cwm are heavily wooded but the valley bottom is free from trees and the barrow thus stands out very clearly. It lies about a mile and a half from the sea at Oxwich Bay, and a little over fifty feet above sea-level. It is in the parish of Penmaen and is marked as ‘Tumulus’ on the current 6 inch (Glam. 22 S.W.) and 1 inch (100 G 11) maps; it is number IOI on the recently published Map of South Wales showing the distribution of Long Barrows and Megaliths, and number 122 in Mr Grimes's recent paper in these Proceedings.

Geological Studies in the Dublin District. I. The Heavy Minerals of the Granite and the Contiguous Rocks in the Ballycorus District

1928 ◽  
Vol 65 (1) ◽  
pp. 12-25 ◽  
Author(s):  
F. Smithson
Keyword(s):  
Geological Structure ◽  
Heavy Minerals ◽  
East Side ◽  
The South ◽  
Large Area ◽  
Lower Carboniferous ◽  
North West ◽  
The North ◽  
South West ◽  
The Hill

From the southern shores of Dublin Bay there stretches to the south-west a broad granite intrusion with rocks of supposed Ordovician age on both sides of it. These rocks are metamorphosed near the granite, and the belt of metamorphism is wider on the south-east than on the north-west side, indicating, no doubt, that the plane of junction dips more steeply on the latter side. Near Dublin the Lower Carboniferous rocks rest unaltered upon the granite. On the south-east side, in the northern part of the county of Wicklow, the belt of Ordovician rocks is only some 2 miles wide, and a large area of supposed Cambrian rocks lies between it and the sea. Around the hill of Carrickgollogan a. patch of similar rocks appears incongruously in the middle of the Ordovician belt. After a study of the region to the south of Dublin one seems to be naturally drawn towards this small area around Carrickgollogan, for it presents a problem, the key to which may explain the geological structure of a much wider area.

THE GEOLOGY OF THE BONAPARTE GULF BASIN

1966 ◽  
Vol 6 (1) ◽  
pp. 7
Author(s):  
T. J. Brady ◽  
W. Jauncey ◽  
C. Stein
Keyword(s):  
Upper Devonian ◽  
The South ◽  
Continuous Section ◽  
Lower Carboniferous ◽  
North West ◽  
Eastern Margin ◽  
South Eastern ◽  
North East ◽  
The North ◽  
Lower Ordovician

An estimated total of over 20,000 feet of Palaeozoic sediments accumulated in the Bonaparte Gulf Basin. The thickest known continuous section is that in Bonaparte No. 1 Well, abandoned at 10,530 feet in Upper Devonian sandstone and shale. Rocks of the Basin margins are mainly sandstones and limestones (in part reef), whereas a thick shale section has been discovered in the deeper parts. Data from recent seismic surveys indicate that the seaward extension of the Basin is considerable and that a thick pile of sediments is preserved there.The Bonaparte Gulf Basin formed as a result of subsidence of the north-eastern part of the Kimberley Block along fault lines associated with the Halls Creek Mobile Zone. This zone borders the south-eastern margin of the Basin and trends north-east. One basement block, represented by the presentday Pincombe Range, remained relatively high. The Bonaparte Gulf Basin can be divided into two subsidiary basins, the Carlton Basin to the west and north-west and the Burt Range Basin in the east and south-east. The Pincombe Range separates the two.Marine sediments were deposited in the Carlton Basin during the Middle and Upper Cambrian, Lower Ordovician, Upper Devonian and Lower Carboniferous epochs. Angular unconformities have been mapped between the Lower Ordovician and Upper Devonian rocks, and between Upper Devonian and Lower Carboniferous rocks. In the Burt Range Basin, deposition began in the Upper Devonian and continued with minor breaks through the Lower Carboniferous. Faults along the south-eastern margin were active through this period and affected the character of the sediments.Permian sediments are widely distributed and lie with unconformity on older units.

Quartz Microfracturing in the North Crop of the South Wales Coalfield

1965 ◽  
Vol 102 (1) ◽  
pp. 59-72 ◽  
Author(s):  
J. C. Roberts
Keyword(s):  
Microscopic Study ◽  
Wide Area ◽  
The South ◽  
Red Sandstone ◽  
The North ◽  
South Wales ◽  
Micro Structures ◽  
Quartz Grains

AbstractA microscopic study of sandstones of Old Red Sandstone and Carboniferous ages along a part of the North Crop of the South Wales Coalfield reveals that the rocks are extensively fractured. The fractures occur in the quartz grains and are often filled with bubble-like inclusions. These planes of inclusion were studied in specimens over a wide area, and are related to the directions of faulting and jointing. The consistency in trend between the macro and micro-structures suggests a homogeneity of the deforming stresses.

The Millstone Grit of Gower

1931 ◽  
Vol 68 (12) ◽  
pp. 529-543 ◽  
Author(s):  
Emily Dix
Keyword(s):  
South Coast ◽  
The South ◽  
North West ◽  
Small Areas ◽  
The North ◽  
South Wales ◽  
Swansea Bay

THE Millstone Grit described in this paper forms a belt of country about a mile wide, stretching from west-north-west to east-south-east across the north of the Gower Peninsula. Reference is also made to small areas of Millstone Grit preserved in synclines at Oxwich and Porteynon on the south coast of Gower. These areas form the most important outcrops of this formation on the south of the South Wales Coalfield. Further east the Millstone Grit is thinner and it is not exposed for some miles to the east of Swansea Bay, as it is concealed by Mesozoic rocks.

Depositional Environment Drive as Overpressure Generation: Study Case in “Gap” Field, North West Java Basin

2020 ◽  
Author(s):  
A., C. Prasetyo
Keyword(s):  
Clay Mineral ◽  
Depositional Environment ◽  
Mineral Content ◽  
Hydrocarbon Generation ◽  
Well Test ◽  
Burial History ◽  
The South ◽  
North West ◽  
The North ◽  
Geological Processes

Overpressure existence represents a geological hazard; therefore, an accurate pore pressure prediction is critical for well planning and drilling procedures, etc. Overpressure is a geological phenomenon usually generated by two mechanisms, loading (disequilibrium compaction) and unloading mechanisms (diagenesis and hydrocarbon generation) and they are all geological processes. This research was conducted based on analytical and descriptive methods integrated with well data including wireline log, laboratory test and well test data. This research was conducted based on quantitative estimate of pore pressures using the Eaton Method. The stages are determining shale intervals with GR logs, calculating vertical stress/overburden stress values, determining normal compaction trends, making cross plots of sonic logs against density logs, calculating geothermal gradients, analyzing hydrocarbon maturity, and calculating sedimentation rates with burial history. The research conducted an analysis method on the distribution of clay mineral composition to determine depositional environment and its relationship to overpressure. The wells include GAP-01, GAP-02, GAP-03, and GAP-04 which has an overpressure zone range at depth 8501-10988 ft. The pressure value within the 4 wells has a range between 4358-7451 Psi. Overpressure mechanism in the GAP field is caused by non-loading mechanism (clay mineral diagenesis and hydrocarbon maturation). Overpressure distribution is controlled by its stratigraphy. Therefore, it is possible overpressure is spread quite broadly, especially in the low morphology of the “GAP” Field. This relates to the delta depositional environment with thick shale. Based on clay minerals distribution, the northern part (GAP 02 & 03) has more clay mineral content compared to the south and this can be interpreted increasingly towards sea (low energy regime) and facies turned into pro-delta. Overpressure might be found shallower in the north than the south due to higher clay mineral content present to the north.

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