scholarly journals The Unconformity between the Millstone Grit and the Carboniferous Limestone at Ifton, Mon.

1921 ◽  
Vol 58 (4) ◽  
pp. 157-164 ◽  
Author(s):  
E. E. L. Dixon
Keyword(s):  
Detailed Examination ◽  
The Other ◽  
Geological Survey ◽  
Present Communication ◽  
The South ◽  
Large Area ◽  
Lower Carboniferous ◽  
South West ◽  
South Wales ◽  
Carboniferous Limestone

The object of the present communication is to place on record a section, apparently unique, in which the unconformity between the Millstone Grit and Carboniferous Limestone that exists in parts of South Wales and Monmouthshire is clearly displayed. The exposure was first examined at the suggestion of the brilliant worker who threw so much light on Lower Carboniferous problems, the late Dr. Vaughan. The writer had explained1 the attenuation of the Carboniferous Limestone Series in the Newport (Mon.) district as due to unconformable overstep by the Millstone Grit, similar to an overstep at this horizon that had already been observed near Haverfordwest, at the other end of the South Wales basin, by Professor O. T. Jones.1 The value of the Ifton section in demonstrating that this overstep was widespread was recognized, and photographs, two of which are here reproduced, were secured by H.M. Geological Survey. Since then the unconformity at the eastern end of the South Wales coalfield has been confirmed by the detailed examination of a large area by Mr. F. Dixey and Dr. T. F. Sibly,2 and has been found by the writer, in the course of work not yet published, to reach its greatest known extent in the Abergavenny district. Nevertheless, it seems desirable to describe the Ifton section because it is the clearest exposure known, in the whole of the South-West Province, of the unconformity between the Carboniferous Limestone and the Millstone Grit, and also on account of the remarkable inter-relations of the two formations which it reveals.

III.— Note on the Faunal Succession in the Carboniferous Limestone (Avonian) near Llantrisant Station in the Bridgend Area, South Wales

1910 ◽  
Vol 7 (2) ◽  
pp. 67-70
Author(s):  
G. Delépine
Keyword(s):  
Present Note ◽  
The South ◽  
South West ◽  
South Wales ◽  
Faunal Succession ◽  
Carboniferous Limestone

During the autumn of 1909, I made a short excursion into the Bridgend district and examined the Avonian sequence near Llantrisant. The present note embodies the results of a few traverses and suggests a correlation with the sequence already established at other points of the South-West Province.

scholarly journals IV.—On a New Species or Discites (Discites Hibernicus) from the Lower Carboniferous Limestone of Ireland

1893 ◽  
Vol 10 (6) ◽  
pp. 251-254
Author(s):  
Arthur H. Foord ◽  
G. C. Crick
Keyword(s):  
New Species ◽  
The Other ◽  
Present Communication ◽  
Lower Carboniferous ◽  
The Subject ◽  
Carboniferous Limestone ◽  
A New Species

The specimen which forms the subject of the present communication was obtained by one of the writers from the Carboniferous Limestone, near Dublin. Although one side of the specimen is covered by matrix, yet the other side and the periphery are so splendidly preserved, and the shell has not been distorted during fossilisation, that the characters of the fossil can be accurately determined (see Woodcut, p. 254).

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.

V.—On Coral Zones in the Carboniferous, Limestone

1910 ◽  
Vol 7 (4) ◽  
pp. 171-173 ◽  
Author(s):  
R. G. Carruthers
Keyword(s):  
Geological Survey ◽  
The South ◽  
Past Season ◽  
The Past ◽  
South West ◽  
Carboniferous Limestone

Amongst the corals collected by the Geological Survey during the past season, and submitted to me for determination, two specimens call for special remark, since they appear at first sight to occur out of their true zonal position. They were found by Mr. Dixon on the Pembrokeshire coast, to the south and south-west of Castle Martin. In each case Mr. Dixon gives the horizon as C2–S1, in the terms of Dr. Vaughan's classification. They are, accordingly, of Lower Visean age.

The Metamorphosed Limestones and Associated Contaminated Igneous Rocks of the Carlingford District, Co. Louth

1932 ◽  
Vol 69 (5) ◽  
pp. 209-233 ◽  
Author(s):  
G. D. Osborne
Keyword(s):  
Igneous Rocks ◽  
The South ◽  
Ordnance Survey ◽  
Igneous Complex ◽  
North East ◽  
The North ◽  
South West ◽  
Carboniferous Limestone ◽  
Contamination Effects

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

Description, distribution and ecology of endemic Tasmanian quillwort, Isoetes jarmaniae, sp. nov. (Isoetaceae; Lycopodiopsida)

Phytotaxa ◽  
2021 ◽  
Vol 522 (1) ◽  
pp. 27-37
Author(s):  
DANIEL F. BRUNTON ◽  
MICHAEL GARRETT ◽  
PAUL C. SOKOLOFF ◽  
GINTARAS KANTVILAS
Keyword(s):  
Diploid Species ◽  
Geographic Range ◽  
The Other ◽  
South American ◽  
The South ◽  
Triangular Shape ◽  
South West ◽  
Distribution And Ecology ◽  
River Valleys

Isoetes jarmaniae sp. nov. is described as a new lycophyte endemic to Tasmania, Australia, where it is confined to peat-bound karstic wetlands in several river valleys in the south-west wilderness. While seemingly morphologically closest to I. drummondii, this quillwort has features that are globally uncommon in Isoetes and unknown in other Australasian taxa. Most notable are its markedly flattened, strongly recurved leaves and disproportionately large sporangium ligules that are more suggestive of South American than Australian taxa. As well, the exceptionally thin and wide (alate) megaspore equatorial ridge is swollen at suture intersections, presenting a slightly triangular shape suggestive of the Indian taxon I. udupiensis. The microspores of I. jarmaniae exhibit exceptionally, perhaps uniquely, fine-papillate ornamentation. An original key placing I. jarmaniae in context with the other Tasmanian Isoetes species is provided. This diminutive, apparently diploid species is evidently maintaining a self-sustaining population within a regionally unique habitat and small geographic range.

V.—On the Shell-Structure of Chonetes Laguessiana, De Kon

1883 ◽  
Vol 10 (8) ◽  
pp. 368-371
Author(s):  
John Young
Keyword(s):  
Shell Structure ◽  
The Other ◽  
Lower Carboniferous ◽  
Carboniferous Limestone

The specimens selected for illustration of the shell-structure of this species of Chonetes were found in a bed of shale in the Lower Carboniferous Limestone series at Capelrig old quarry, in the parish of East Kilbride, Lanarkshire. The fossils in this shale have their structure generally well preserved, there being less change, through crystallization of the lime present in the shells of the various organisms, than is found in those obtained from most of the other fossiliferous localities in Western Scotland.

1. On Annelid Tracks in the Exploration of the Millstone Grits in the South-west of the County of Clare.

1857 ◽  
Vol 3 ◽  
pp. 294-295
Author(s):  
Robert Harkness
Keyword(s):  
The Other ◽  
Perfect State ◽  
The South ◽  
Great Abundance ◽  
South West ◽  
Soft State ◽  
The One ◽  
To Receive

The author remarks that the existence of Annelida during the Palæozoic formations is manifested in two conditions. In the one, we have the shelly envelope which invests the order Tubicola, in the form of Seapolites; and in the other, the tracks of the orders Abranchia and Dorsi-branchiata are found impressed on deposits which were, at one time, in a sufficiently soft state to receive the impressions of the wanderings of these animals.Among the strata which have hitherto afforded annelid tracks, those which, in the county of Clare, represent a portion of the equivalents of the Millstone Grit, contain such tracks, in their most perfect state of preservation in great abundance; and these strata also furnish evidence concerning the circumstances which prevailed during their deposition.

On Composite Lava Flows.

1931 ◽  
Vol 68 (4) ◽  
pp. 166-181 ◽  
Author(s):  
W. Q. Kennedy
Keyword(s):  
Lava Flow ◽  
Lava Flows ◽  
The Other ◽  
Geological Survey ◽  
Main Subject ◽  
Lower Carboniferous ◽  
Fluid State ◽  
Mutual Contact ◽  
The World ◽  
Probable Effect

For many years composite minor intrusions, both sills and dykes, have been known from various parts of the world and most petrologists must have speculated as to the probable effect produced in the event of such composite intrusions having reached the surface in the form of an effusion. For obvious reasons it has not been found possible to trace a composite dyke upwards into a lava flow. However, during the revision of 1 inch Sheet 30 (Renfrewshire) for the Geological Survey, the author encountered, in the neighbourhood of Inverkip, a small village on the Firth of Clyde south of Greenock, certain peculiar lava flows which are believed to represent the effusive equivalents of composite minor intrusions. These “composite lavas”, which form the main subject of the present paper, are of Lower Carboniferous age (Calciferous Sandstone Series) and occur interbedded among the more normal flows towards the base of the volcanic group. Two distinct rock varieties, one highly porphyritic, with large phenocrysts (up to 1·5 cms. long) of basic plagioclase, and the other non-porphyritic, are associated within the same flow. The porphyritic type always forms the upper part of the flow and overlies the non-porphyritic; the junction shows unmistakable evidence that both were in a fluid state along their mutual contact at the time of emplacement.

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