III.—A remarkable instance of Rock Differentiation

1908 ◽  
Vol 5 (8) ◽  
pp. 344-352
Author(s):  
Harford J. Lowe
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
The South ◽  
Different Parts ◽  
The Hamlet

Upon Sheet 339 (Devonshire) of the new Geological Survey maps, one instance out of the very numerous outcrops of igneous rocks thereon indicated proves to be of unusual interest by reason of its peculiar constitutional modifications in different parts of the same mass. The rockin question occurs about four and a quarter miles 15° north of west from Newton Abbot, near to the hamlet of Bickington, within the limits of a farm named Lurcombe. It is an intrusive amidst the shales and grits of the Culm, occurring almost on the junction-line between that series and the Devonian, whose massive limestones and volcanics dominate it in elevation within a quarter of a mile on the south-east.

scholarly journals IV.—On the Lower Silurian Rocks of Galashiels

1870 ◽  
Vol 7 (71) ◽  
pp. 204-209 ◽  
Author(s):  
Charles Lapworth
Keyword(s):  
The Other ◽  
Geological Survey ◽  
The South ◽  
Lower Silurian ◽  
The Government ◽  
Different Parts ◽  
Made In

The Lower Silurian rocks of Scotland, largely developed as they are in the south, and in spite of the great labour that has been bestowed upon them, are by far the least known of all the fossiliferous formations of that country. While the maps of the Government Geological Survey are coloured in all the subdivisions of the strata of the other formations included in their area, the Lower Silurians are merely indicated by a common purple tint, and not the slightest attempt at a subdivision is made. Even the single bed of Limestone they contain, below the horizon of that of the W. coast, is doubtfully referred to the Llandeilo, and the sign of interrogation is carefully placed before its title. Nicol, Harkness, J. C. Moore, and many other eminent geologists, have worked different portions of these ancient deposits since the publication of “The Silurian System,” but as yet very little progress has really been made in correlating its different parts with those of the type formation of the sister country.

VI.—The Picrite of Foel lwyd, Carnarvonshire

1913 ◽  
Vol 10 (3) ◽  
pp. 108-109
Author(s):  
J. E. Wynfield Rhodes
Keyword(s):  
Volcanic Rocks ◽  
Igneous Rocks ◽  
Geological Survey ◽  
The South ◽  
North Wales

During a short holiday to North Wales in Whit-week, 1910, I was investigating the igneous rocks to the south of Llanfairfechan, more particularly the intrusive greenstones of the Geological Survey map. Since the publication of this map, over fifty years ago, several districts within it have been investigated in greater detail, especially as to the volcanic rocks, but much remains to be done petrographically. One of these greenstones turned out to be of exceptional interest, being of a type of rock hitherto, I believe, unrecorded in North Wales, so another visit was made to it in August, 1912.

scholarly journals III.—An Irish Augitite

1892 ◽  
Vol 9 (8) ◽  
pp. 348-350 ◽  
Author(s):  
Bernard Hobson
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
The South ◽  
Isle Of Man ◽  
Coal Measures

When writing my paper “On the Igneous Rocks of the South of the Isle of Man,” I was led to compare a Manx melaphyre, from Scarlet Point, with a rock described by Prof. E. Hull as a melaphyre, occurring at Ballytrasna, near Limerick, and belonging to the “Upper Trap-band,” a little below the basal shales of the Coal-measures. Through the kindness of Prof. Hull, a chip of the rock was sent to me by the Irish Geological Survey. The specimen was black and basaltic-looking. I did not obtain satisfactory sections of it in time for my paper, but have since had excellent ones made. On examining them I was immediately struck by the resemblance of the rock to the augitite of Paschkapole, between Velmin and Boreslau, in Bohemia, with a section of which I compared it. Professor Hull describes the rock of Ballytrasna as containing “numerous large crystals and groups of banded felspar”; but I failed to find a single felspar in four sections, nor did I observe any in Allport's section, No. 1902, from the same locality, which agrees with my sections.

scholarly journals Tertiary volcanic rocks from Bontekoe Ø, East Greenland

1983 ◽  
Vol 116 ◽  
pp. 1-13
Author(s):  
A Noe-Nygaard ◽  
A.K Pedersen
Keyword(s):  
Volcanic Rocks ◽  
Igneous Rocks ◽  
Geological Survey ◽  
The South ◽  
East Greenland ◽  
The Third ◽  
The North

In East Greenland Tertiary igneous rocks are found from Kap Gustav Holm (66°30'N) in the south to Shannon (75°30'N) in the north. Within this region three areas are covered by plateau basalts; (a) south of Scoresby Sund (700N), (b) far inland on the nunataks at 74°N and (c) along the coast between 73° and 75°30'N. Bontekoe ø belongs to the third region (fig. 1). The geology of this part of East Greenland is largely known from the activities of Lauge Koch's expeditions during which, curiously enough, the areas dominated by Tertiary volcanism were almost neglected. To remedy this the Geological Survey of Greenland supported some reconnaissance work that was carried out in connection with other geological activity in the region over the last few years. Results of this work were given by NoeNygaard & Pedersen (1974), Upton & Emeleus (1977), Hald (1978), Brooks et al. (1979) and Upton et al. (1980, 1982, in press).

Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996

1997 ◽  
pp. 66-74
Author(s):  
Henrik Stendal ◽  
Wulf Mueller ◽  
Nicolai Birkedal ◽  
Esben I. Hansen ◽  
Claus Østergaard
Keyword(s):  
Mineral Exploration ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Field Work ◽  
Igneous Rocks ◽  
Border Zone ◽  
The South ◽  
East Greenland ◽  
North West ◽  
Arc Setting

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stendal, H., Mueller, W., Birkedal, N., Hansen, E. I., & Østergaard, C. (1997). Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 66-74. https://doi.org/10.34194/ggub.v176.5064 _______________ The multidisciplinary SUPRASYD project (1992–96) focused on a regional investigation of the Palaeoproterozoic Ketilidian orogenic belt which crosses the southern tip of Greenland. Apart from a broad range of geological and structural studies (Nielsen et al., 1993; Garde & Schønwandt, 1994, 1995; Garde et al., 1997), the project included a mineral resource evaluation of the supracrustal sequences associated with the Ketilidian orogen (e.g. Mosher, 1995). The Ketilidian orogen of southern Greenland can be divided from north-west to south-east into: (1) a border zone in which the crystalline rocks of the Archaean craton are unconformably overlain by Ketilidian supracrustal rocks; (2) a major polyphase pluton, referred to as the Julianehåb batholith; and (3) extensive areas of Ketilidian supracrustal rocks, divided into psammitic and pelitic rocks with subordinate interstratified mafic volcanic rocks (Fig. 1). The Julianehåb batholith is viewed as emplaced in a magmatic arc setting; the supracrustal sequences south of the batholith have been interpreted as either (1) deposited in an intra-arc and fore-arc basin (Chadwick & Garde, 1996), or (2) deposited in a back-arc or intra-arc setting (Stendal & Swager, 1995; Swager, 1995). Both possibilities are plausible and infer subduction-related processes. Regional compilations of geological, geochemical and geophysical data for southern Greenland have been presented by Thorning et al. (1994). Mosher (1995) has recently reviewed the mineral exploration potential of the region. The commercial company Nunaoil A/S has been engaged in gold prospecting in South Greenland since 1990 (e.g. Gowen et al., 1993). A principal goal of the SUPRASYD project was to test the mineral potential of the Ketilidian supracrustal sequences and define the gold potential in the shear zones in the Julianehåb batholith. Previous work has substantiated a gold potential in amphibolitic rocks in the south-west coastal areas (Gowen et al., 1993.), and in the amphibolitic rocks of the Kutseq area (Swager et al., 1995). Field work in 1996 was focused on prospective gold-bearing sites in mafic rocks in South-East Greenland. Three M.Sc. students mapped showings under the supervision of the H. S., while an area on the south side of Kangerluluk fjord was mapped by H. S. and W. M. (Fig. 4).

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.

Bridge River tephra: revised distribution and significance for detecting old carbon errors in radiocarbon dates of limnic sediments in southern British Columbia

1980 ◽  
Vol 17 (11) ◽  
pp. 1454-1461 ◽  
Author(s):  
Rolf W. Mathewes ◽  
John A. Westgate
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lacustrine Sediments ◽  
Igneous Rocks ◽  
The South ◽  
Radiocarbon Dates ◽  
Carbon Contamination ◽  
Horseshoe Lake ◽  
Tephra Beds

Ash-grade Bridge River tephra, identified as such on the basis of shard habit, modal mineralogy, and composition of ilmenite, occurs in sedimentary cores from three lakes located to the south of the previously documented plume and necessitates a significant enlargement of the fallout area of that tephra in southwestern British Columbia.These new, more southerly occurrences are probably equivalent to the ~2350 year old Bridge River tephra, although it can be argued from the evidence at hand that the 14C dates and biotite-rich nature support relationship to a slightly earlier Bridge River event.Large differences exist in the 14C age of sediments immediately adjacent to the Bridge River tephra at these three lake sites; maximum ages of 3950 ± 170 years BP (GX-5549) and 3750 ± 210 years BP (I-10041) were obtained at Phair and Fishblue lakes, respectively, whereas the corresponding age at Horseshoe Lake is only 2685 ± 180 years BP (GX-5757). The two older dates are considered to be significantly affected by old carbon contamination for the bedrock locally consists of calcareous sedimentary rocks and the lacustrine sediments are very calcareous. The 14C date from Horseshoe Lake, which occurs in an area of igneous rocks, appears to be only slightly too old relative to the ~2350 year old Bridge River tephra.Well-dated tephra beds, therefore, can be very useful in assessing the magnitude of old carbon errors associated with radiocarbon dates based on limnic sediments. Calcareous gyttja deposits beneath Bridge River tephra within the study area exhibit old carbon errors of the order of 1350–1550 years.

scholarly journals On the Geology of the Beaufort and Ebbw Vale District of the South Wales Coal-Field

The Geologist ◽  
1858 ◽  
Vol 1 (4) ◽  
pp. 124-129
Author(s):  
George Phillips Bevan
Keyword(s):  
Bituminous Coal ◽  
Health It ◽  
Coal Field ◽  
The South ◽  
Great Demand ◽  
South Wales ◽  
Burning Coal ◽  
Coal Measures ◽  
Different Parts ◽  
General Appearance

In my former paper I endeavoured to describe the general appearance and characteristics of the limestone, millstone grit, and Pennant rocks of this coal-field, and shall now proceed to give a brief outline of the coal measures themselves and their fossil contents. As I stated before, the character of the coal is materially different in different parts of the basin; for instance, if a line be drawn from Merthyr to the sea in a south-western direction, it will divide the basin into two unequal portions, the eastern one containing bituminous coal, and the western the anthracite. I do not mean to say that there is an exact line of demarcation between the two kinds of coal, but merely that such a boundary will seem to show pretty well where the two qualities pass into one another. Curiously enough, too, in the western or anthracite portion the seams are anthracitic in the northern bassets, while the southern outcrops of the same veins are bituminous. The anthracite is now in very great demand; but, formerly, people would have nothing to do with it, and there was even a law passed to prevent its being burned in London, on account of its supposed noxious qualities, and the idea that it was detrimental to health. It differs from the bituminous coal principally in containing more carbon, less bituminous matter, and less ashes; and, as a consequence, is a much cleaner-burning coal. We may, however, dismiss the anthracite, as this portion of the field is destitute of it.

scholarly journals XV.—On some new Species of Fossil Scorpions from the Carboniferous Rocks of Scotland and the English Borders, with a Review of the Genera Eoscorpius and Mazonia of Messrs Meek and Worthen

1881 ◽  
Vol 30 (1) ◽  
pp. 397-412 ◽  
Author(s):  
B. N. Peach
Keyword(s):  
New Species ◽  
Great Britain ◽  
Geological Survey ◽  
Director General ◽  
The South ◽  
Coal Measures

In the progress of the Geological Survey of the South of Scotland, specimens referable to the genus Eoscorpius have been gradually accumulating. In 1876 J. Bennie, Fossil Collector to the Survey, obtained an example from the Coal-measures of Fife. Since then fragments have been disinterred by him and by A. Macconochie, also Fossil Collector to the Survey, from the Calciferous Sandstone series in the counties of Edinburgh, Berwick, Roxburgh, Dumfries, and Northumberland and Cumberland. It was not till the spring of last year (1880) that they began to be found in such a state as to necessitate a description of the fossils. In the summer of that year A. Macconochie obtained an almost entire example from the neighbourhood of Langholm, in Dumfriesshire. This year (1881) J. Bennie has secured several good though fragmentary specimens from the neighbourhood of Edinburgh, while A. Macconochie has sent in several from the counties of Berwick and Northumberland. In my capacity of Acting Palæontologist, I have had an opportunity of studying these remains, and by the permission of A. C. Ramsay, LL.D., F.R.S., Director General of the Geological Survey of Great Britain, and Professor A. Geikie, LL.D., F.R.S., Director of the Geological Survey of Scotland, I have been allowed to describe them.

scholarly journals X.—On the Greenstone and Associated Rocks of the Manacle Point, Lizard

1889 ◽  
Vol 6 (9) ◽  
pp. 425-427
Author(s):  
Alexander Somervail
Keyword(s):  
Good Reason ◽  
Geological Survey ◽  
The South ◽  
Main Mass ◽  
Considerable Distance ◽  
The North ◽  
North Side ◽  
South Wall

On De La Beche's Geological Survey Map of Cornwall are three colours representing the associated rocks at, and on each side of the Manacle Point. The Point itself and for a considerable distance south of it is represented as a greenstone. Partially encased in the greenstone and to the south of it is gabbro, which forms the main mass of this rock in the Lizard district. On the north side of the greenstone which forms the extreme south wall of Porthonstock Cove is hornblende-schist, which with some serpentine and other rocks terminates against the killas, or slates near Porthalla.Several observers with seeming good reason have drawn attention to the fact that the greenstone as represented on the map is made to cover much too large an area to the south, and that any one walking from this direction, or the reverse, finds gabbro where the former rock was expected to occur.

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