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VIII.—The Lower Carboniferous Volcanic Rocks of East Lothian (Garlton Hills)

Published online by Cambridge University Press:  06 July 2012

Frederick H. Hatch
Affiliation:
Geological Survey

Extract

The rich agricultural tract of country that forms the north-western part of East Lothian, undulating uniformly from the foot of the chain of the Lammermuirs towards the Firth of Forth, swells near Haddington into the cluster of the Garlton Hills, and the neighbouring masses of Traprain Law and North Berwick Law.

The rocks that build up this elevated ground are lavas and tuffs that were produced during the period of volcanic activity that characterised the deposition of the Lower Carboniferous beds of Scotland. In East Lothian their eruption followed close on the deposition of the sandstones and marls that constitute the base of the calciferous sandstone group.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1895

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References

page 115 note * Geikie, A., Trans. Roy. Soc. Edin., vol. xxix., 1680, p. 447Google Scholar. See also his Presidential Address to the Geological Society, 1892.

page 115 note † Loc. cit.

page 116 note * A. Geikie, loc. cit.

page 116 note † Survey Memoir on East Lothian, p. 47, and Sir A. Geikie's Presidential Address already cited.

page 116 note ‡ The name limburgite was first applied by Rosenbusch to the rock of the Kaiserstuhl in Breisgau. Limburgites have since been described from numerous foreign localities, but are hitherto unrecorded in Great Britain. Quite recently I have been able to note the occurrence of a similar type among the basic rocks of the Carboniferous volcanic series in several places in Scotland besides that of Whitelaw Hill, e.g., Hill of Beath, Cowdenbeath (Fife); Pitandrew, Fordel Castle (Fife); Southdean Law, 7 miles south of Jedburgh.

page 116 note § A similar appearance is described by Bořický as characteristic for his “lichte Magmabasalt.”

page 117 note * Knop, A., Zeitschrift für Krystallographie, vol. x., 1885, p. 58Google Scholar.

page 117 note † No. 631 of the Survey Collection.

page 117 note ‡ The Kippie Law type is occasionally found in other areas occupied by the Carboniferous volcanic rocks of Scotland. Thus it occurs south of Jedburgh, at Neides Law and Bonchester Hill, also in the Campsie Hills, 1½ miles north of Lennoxtown. It is nearly allied to rocks of the Dalmeny type, which are abundantly distributed. It differs from these in the presence of porphyritic felspars.

page 118 note * No. 630 of the Survey Collection.

page 119 note * No. 629 of the Survey Collection.

page 120 note * The Puy de Dome trachyte has SiO2, 62·83; K2O, 8·88; Na2O, 5·03—one of the Rhön trachytes; SiO2, 63·40; K2O, 3·54; Na2O, 8·39 (Kalkowsky)—trachyte from Monte del' Imperatore, Italy; SiO2, 61·05; K2O, 5·28; Na2O, 5·94—trachyte from Monte Vettia; SiO2, 61·87; K2O, 6·51; Na2O, 5·07.—(J. Roth.)

page 121 note * Some North of England Dykes, Quart. Journ. Geol. Soc., 1884, p. 234.

page 122 note * Figured by Sir Archibald Geikie,, loc. cit.

page 122 note † These analyses were kindly made for me by Messrs G. Barrow and A. Dick, jun., in the Laboratory of the Geological Survey at 28 Jermyn Street, London.

page 123 note * The only phonolite that has hitherto been described in the British Isles is that of the Wolf Kock, off the coast of Cornwall.

page 123 note † In the Survey Memoir on East Lothian (p. 51), North Berwick Law is described as “a round or slightly oval plug of felstone, which comes up vertically through the ash, and when it reaches the surface of the ground tapers up into a cone, of which the top is 612 feet above the sea. The rock on the higher part of the hill is a compact and finely crystalline clinkstone, while further down it becomes more loose and granular in texture. At the foot of the cone, on the west side, sandstone and black shale (strata, probably in the ashy series) are seen to dip away from the felstone at an angle of 30°.”

page 124 note * This property, which appears to be a characteristic of the phonolites, was noticed in the Survey Memoir (p. 52), where the rock of Traprain Law is described as a “felstone (clinkstone).”

page 125 note * The low index of refraction, and the absence of a needle-form, serve as a distinction from apatite. Professor Rosenbusch of Heidelberg, to whom I submitted specimens, confirms the identification of the nepheline, and refers the rock to the trachytic phonolites of his classification.