« PreviousContinue »
From 4 to 3.
1. Faraday's researches on gold-leaf best illustrate this; but I hold that my explanation of them by masses of two degrees of complexity only is sufficient without his conclusion (Researches in Chemistry,' p. 417), that they exist "of intermediate sizes or proportions.
From 3 to 2.
1. Sulphur-vapour first gives a continuous spectrum at the blue end; on heating, this breaks up into a channelled space-spectrum. 2. The new spectra of K and Na (more particularly referred to in the third note) make their appearance after the continuous absorption in the blue and red vanishes.
From 2 to 1.
1. In many metalloids the spectra, without the jar, are channelled; on throwing the jar into the circuit the line-spectrum is produced, while the cooler exterior vapour gives a channelled absorption-spectrum.
2. The new spectra of K and Na change into the line-spectrum (with thick lines which thin subsequently) as the heat is continued.
[Continued from p. 153.]
March 25th, 1874.-John Evans, Esq., F.R.S., President,
The following communications were read :—
1. "On the Upper Coal-Formation of Eastern Nova Scotia and Prince Edward Island, in its relation to the Permian." By Principal Dawson, LL.D., F.R.S., F.G.S.
The author described the Carboniferous district of Pictou County as showing the whole thickness of the Carboniferous system arranged in three synclinals, the easternmost consisting of the Lower series up to the Middle Coal-formation, and including all the known workable Coal-measures in the district,-the second towards the west of the middle and the lower part of the Upper Coal-formation,and the third showing in its centre the newest beds of the latter. On the north the bounding anticlinal of the first depression brings up the New-Glasgow Conglomerate, which contains boulders 3 feet in diameter, often belonging to Lower Carboniferous rocks, and represents the upper part of the Millstone-grit or the lower part of the Middle Coal-formation. The author regards this as representing an immense bar or beach, which protected the swamps in which the Pictou main coal was formed.
The succession of the deposits above the Conglomerate was described in some detail as seen in natural sections. The Upper Coal-formation, as shown in the section west of Carribou Harbour, consists of:-1. Red and grey shales and grey, red, and brown sandstones; and 2. Shales, generally of a deep red colour, alternating
with grey, red, and brown sandstones, the red beds becoming more prevalent in the upper part of the section. In Prince-Edward Island beds apparently corresponding to these are found, and also gradually become more red in ascending. These are overlain, apparently conformably, by the Trias.
The author gave a tabular list of 47 species of plants found in the Upper Coal-formation of Nova Scotia and Prince-Edward Island, and stated that all but about ten of these occur also in the Middle Coal-formation. The number of species decreases rapidly towards the upper part of the formation; and this is especially the case in Prince-Edward Island, some of the beds in which are considered by the author to be newer than any of those in Nova Scotia. The plants contained in the upper deposits were compared with those of the European Permian, and a correlation was shown to exist between them; so that it becomes a question whether this series was not synchronous with the lower part of the Permian of Europe, although in this district there is no stratigraphical break to establish a boundary between Carboniferous and Permian. The author therefore proposes to name these beds Permo-Carboniferous, and regards them as to some extent bridging over the gap which in Eastern America separates the Carboniferous from the Trias.
2. Note on the Carboniferous Conglomerates of the eastern part of the Basin of the Eden." By J. G. Goodchild, Esq. Communicated, by permission of the Director-General of the Geological Survey of the United Kingdom, by H. W. Bristow, Esq., F.R.S., F.G.S.
The author commenced by describing in detail the series of beds between the true Basement series of the Carboniferous and the Mountain Limestone as shown in sections at Ash Fell. The general sequence in descending order is as follows:
a. Carboniferous Limestone, with a few thin beds of stained sandstone and shale; thickness not less than 1000 feet;
b. Obliquely laminated soft red sandstones, with coal-measure plants, frequently conglomeratic, alternating with fossiliferous shales and beds of limestone; thickness about 500 feet;
c. Limestone, 500 or 600 feet thick, passing down into
d. Shales with thin impure limestones, passing down through calcareous conglomeratic beds into a series of apple-geeen quartz conglomerates and chocolate and grey shales, succeeded without any clear line of separation by the drift-like red conglomerates, sandstones, and shales forming the lower part of the Carboniferous Basement beds, which has been regarded as the equivalent of the Upper Old Red elsewhere.
The author described the mode of occurrence of these deposits in various parts of the district under consideration, and the disturbances which have affected their surface distribution. Along the Cross-Fell escarpment a group of sandstones and conglomerates occupies an exceedingly prominent position, especially at and near
Roman Fell, whence the author proposes to call these deposits the Roman-Fell beds. These beds represent the series b, and also the lower part of a, at Ash Fell. Following their outcrop towards Cumberland, the conglomeratie beds from the middle downwards increase much in thickness and become much coarser. The author regards the Roman-Fell beds as approximately on the horizon of the Calciferous Sandstone series of the south of Scotland; and he remarks that they are locally undistinguishable from much of the Basement series, and have been described by authors as undoubted Old Red Sandstone.
3.An Account of a Well-section in the Chalk at the North end
of Driffield, East Yorkshire." By R. Mortimer, Esq. Communicated by W. Whitaker, Esq., F.G.S.
In this paper, which was in continuation of a former communication to the Society (Q. J. G. S. vol. xxix. p. 417), the author stated that the well-section referred to passed through 7 feet of clay and 47 feet of chalk, the upper 3 or 4 feet of the latter very rubbly and broken. The chalk was bedded in lamine of from in. to 16 in. thick. From a depth of 20 feet downwards the well exposed many nearly vertical partings running in all directions through the Chalk; and the surfaces of the blocks thus marked out showed numerous striæ, such as were described in the author's former paper. These striæ were in most cases horizontal; but some surfaces showed them at an angle of 45° to the horizon. The lamina of which the chalk was composed were separated by layers of a softer substance like fuller's earth, containing 1-67 per cent. of organic matter, 7.05 per cent. of oxide of iron, 10-23 per cent. of alumina, and 34-80 per cent. of silica. The author regards this soft substance as formed by the disintegration of chalk, shells, &c., caused probably by the periodical prevalence of great waves or other disturbances in the Cretaceous sea. The effect of its formation he considers would be to check the upward growth of the mass of chalk, which he now, as formerly, ascribes to the direct secreting action of numerous zoophytes, In support of this view he states that the surfaces of the chalk laminæ are more or less irregular-and not even, as if produced by quiet sedimentary deposition. The paper contained detailed analyses of the chalk and of the soft partings.
4. "On Slickensides or Rock-striations, particularly those of the Chalk." By Dr. Ogier Ward. Communicated by Prof. Morris, F.G.S. The author referred to previous communications on this subject, and maintained that the striæ observed in chalk are to be regarded as slickensides caused by disturbance and movement of the rock. He described the appearances in detail, and mentioned the occurrence of similar striations in various rocks.
April 15th, 1874.-John Evans, Esq., F.R.S., President,
The following communications were read :—
1. "About Polar Glaciation." By J. F. Campbell, Esq., F.G.S. The author commenced by referring to a reported statement of
Prof. Agassiz, to the effect that he supposed the northern hemisphere to have been covered in glacial times from the pole to the equator by a solid cap of ice. He described his observations made during 33 years, and especially those of last summer, when he travelled from England past the North Cape to Archangel, and thence by land to the Caucasus, Crimea, Greece, and the South of Europe. His principal results were as follows:-In advancing southwards through Russia a range of low drift hills occurs about 60° N. lat., which may perhaps form part of a circular terminal moraine left by a retreating polar ice-cap; large grooved and polished stones of northern origin reach 55° N. lat. at Nijni Novgorod, but further. east and south no such stones could be seen. The highest drift beds along the whole course of the Volga seem to have been arranged by water moving southwards. In America northern boulders are lost about 39°, in Germany about 55°, and in Eastern Russia about 56° N. lat., where the trains end and fine gravel and sand cover the solid rocks. Ice-action, in the form either of glaciers or of icebergs, is necessary to account for the transport of large stones over the plains, and the action of moving water to account for drift carried further south. There are no indications of a continuous solid ice-cap flowing southward over plains in Europe and America to, or nearly to, the Equator; but a great deal was to be found on shore to prove ancient ocean circulation of equatorial and polar currents, like those which now move in the Atlantic, and much to prove the former existence of very large local ice-systems in places where no glaciers now exist.
2. "Note regarding the occurrence of Jade in the Karakash Valley, on the southern borders of Turkestan." By Dr. Ferdinand Stoliczka, F.G.S., Naturalist attached to the Yarkund Mission.
In this paper the author described the jade-mines on the right bank of the Karakash river formerly worked by the Chinese. There are about 120 holes in the side of the hill; and these at a little distance look like pigeon-holes. The rocks are a thin-bedded rather sandy syenitic gneiss, mica- and hornblende-schists, traversed by veins of a white mineral, apparently zeolitic, which in turn are traversed by veins of jade.
April 29, 1874.-John Evans, Esq., F.R.S., President, in the Chair. The following communications were read:
1. "On the Gault of Folkestone." By F. G. H. Price, Esq., F.G.S. The author divided the Gault into two great sections, Upper and Lower Gault, which he again subdivided into eleven well-defined zones, mostly named after characteristic Ammonites. Each of these zones or beds is numbered, commencing with No. XI., the zone of Ammonites interruptus, which bed forms the base of the Gault, reposing upon the Folkestone beds of the Upper Neocomian.
He found the thickness of the deposit at Copt Point to be 99 feet 4 inches.
He had collected as many as 228 species from the beds, including the following new species-Avellana pulchella, Natica obliqua, and Nucula De Rancei-which he described.
The paper was accompanied by a table of species, setting forth the various beds in which the particular fossils have been met with.
2. "On the Cretaceous Rocks of Beer Head and the adjacent Cliff-sections; and on the relative Horizons therein of the Warminster and Blackdown Fossiliferous deposits." By C. J. A. Meyer, Esq., F.G.S.
The author remarked that in advancing westward from the Isle of Wight the Cretaceous rocks diminish steadily, although unequally, in thickness, and change slightly both in mineral character and fossil contents, while the base of the series rises gradually in the cliff-sections. The chalk-cliffs of Beer Head, the most westerly chalk promontory in England, owe their preservation, in his opinion, partly to a local synclinal arrangement of the strata. The Cretaceous rocks of the district include the following, in descending order ::-
Upper Chalk (in part)?
The author described in detail the minor subdivisions of these series, and gave lists of the fossils found in them in situ. The base of the section is occupied by beds which he identified with those of Blackdown, certainly underlying the Upper Greensand, and apparently occupying the position of the Gault or of the Gault and Upper Neocomian in part. The Warminster beds, on the contrary, were said to cap the Upper Greensand, and to be in reality Chloritic Marl. The author suggested that the term Upper Greensand should be applied exclusively to beds between the Gault and Chloritic Marl, and that the latter should be considered a distinct division.
May 13th, 1874.-John Evans Esq., F.R.S., President,
The following communications were read :-
1. "Note on some of the Generic Modifications of the Plesiosaurian Pectoral Girdle." By Harry G. Seeley, Esq., F.L.S., F.G.S.
The author stated that Plesiosauria differ from all living reptilia, except Chelonians, in wanting a sternum, and pointed out the resemblance between the plesiosaurian coracoid and the coracoid and precoracoid of Chelonians, inferring that the plesiosaurian scapulæ had been carried forward by the potential ossification which elonPhil. Mag. S. 4. Vol. 49. No. 324. March 1875. R