62 



NATURE 



[January 12, 1922 



Societies and Academies. 



LONDOiN. 



Geological Society, December 21, 1921. — Mr. R. D. 

 Oldham, president, in the chair.— H. B. Milner : The 

 nature and origin of the Pliocene deposits of the 

 County of Cornwall and their bearing on the Pliocene 

 geography of the south-west of England, Tertiary 

 deposits of Cornwall at St. Agnes, St. Erth, Lelant 

 Downs, Polcrebo, and St. Keverne have been provi- 

 sionally assigned to the Pliocene period ; except those 

 of St. Erth, all are unfossiliferous. The average com- 

 position of the St. Agnes, St. Erth, and St. Keverne 

 deposits is substantially the same. On this basis 

 correlation of the deposits is effected by (a) the fre- 

 quency of occurrence of individual species, (b) their 

 persistence or distribution, and (c) the constancy of 

 crystallographical, physical, and optical properties of 

 grains of the same mineral, wherever met. The 

 source of the material is essentially local. The gradual 

 "swamping" of sediment-bearing rivers by the ad- 

 vancing Pliocene sea from the south-west is correlated 

 with certain physical features apparent, especially the 

 "400-ft. plateau." — L. Owen: The phosphate deposit 

 of Ocean Island. Ocean Island, in the Western 

 Pacific Ocean, consists of a mass of terraced and 

 dolomitised coral-limestone which rises to a height of 

 300 ft. above low water, spring tide. Its surface is 

 almost completely covered by a capping of calcium 

 phosphate of exceptional purity which can be divided 

 into three varieties : (a) Amorphous calcium phos- 

 phate, formed of the insoluble residue of the original 

 guano; (&) detrital coral-limestone, converted into 

 calcium phosphate by solutions leached from the 

 guano; and (c) phosphatised coral in situ. The per- 

 centage of tricalcium phosphate at any point varies in 

 a remarkably regular manner, according to the posi- 

 tion of the point on the island, suggesting that (a) the 

 original guano was deposited on the coral base during 

 a slow negative movement of the strand-line, and 

 (b) subsequent to the formation of phosphate the 

 island was tilted at about a third of a degree south- 

 south-eastwards. 



Edinburgh. 



Royal Society, December 5, 192 1.— Prof, J. W. 

 Gregory, vice-president, in the chair.— Prof. Jehu :' 

 Observations on the geology of lona. The Archaean 

 complex of the western and greater part of lona con- 

 sists mainly of orthogneisses of dominant acid and 

 hornblendic types, although pvroxene-hornblende 

 gneiss and garnetiferous pyroxene granulites also 

 occur. Paragneisses of various kinds are found at 

 isolated localities as lenticular masses in the ortho- 

 gneisses. On the south coast the forsterite-tremolite 

 marble (lona marble) is associated with hornfelsed 

 green rocks, some of which are altered sediments 

 and some altered igneous rocks. The paragneisses are 

 younger than, and unconformable to, the ortho- 

 gneisses, and represent remnants of pre-Torridonian 

 rocks which became infolded with the orthogneisses. A 

 massive white pegmatite forms a prominent feature 

 in the landscape from the marble quarry on the south 

 coast to near the centre of the island. A belt of 

 Torridonian beds lying unconformably on the Archeean 

 forms the eastern margin of the island, and consists 

 of a lower group of epidotic conglomerates and grits 

 and an upper group of finer grits, slates, shales, and 

 banded flags. The Torridonian series of lona may be 

 correlated with the lower parts of the Diabaig group 

 of that series in Skye and other districts. In post- 

 Torridonian time the Archaean and Torridonian rocks 

 have been subjected to isoclinal folding, the Archaean 

 NO. 2724, VOL. 109] 



series being dragged more or less Into approximate 

 parallelism with the Torridonian. Along the line of 

 junction there has been considerable crushing, but 

 no actual thrust. The Torridonian rocks show 

 dynamic metamorphism, and the later intrusion 

 of the Ross of Mull granite has resulted in 

 a later thermal metamorphism. This granite 

 forms three small islets close to the south-east 

 shore, and probably underlies the southern half of 

 lona. A series of genetically connected minor intru- 

 sions occur, and, with the granite, belong probably to 

 the Caledonian phase of igneous activity. — H. M. 

 Cadell : The geology of the Blackness district. Recent 

 borings for oil-shale and coal in the Blackness district 

 south of the Firth of Forth have not disclosed much 

 mineral wealth, but have provided a complete vertical 

 section of the Oil-Shale series in that region, indi- 

 cating a notable attenuation of the whole shale section 

 towards the north and west. To the west of Black- 

 ness no workable oil-shale was found above the 

 Burdiehouse Limestone, although the positions of the 

 seams were recognisable. The borings were continued 

 westward up to the Bo'ness coal-seams of the Car- 

 boniferous Limestone series through ground that had 

 never been previously explored. Six distinct beds of 

 limestone had been found varying much in thickness 

 from place to place. The No. 5 limestone measuring 

 from the top downwards appeared from its fauna to 

 be the equivalent of the Blackball Limestone of the 

 West of Scotland. The old volcano of Binns Hill 

 to the south of Blackness belonged to the volcanic 

 horizon situated near the top of the oil-shale section 

 between the Two Feet Coal and the overlying Raeburn 

 Shale seam. There had been much boring and mining 

 for shale under the east end of the hill, and the evi- 

 dence showed that within a few hundred yards of the 

 thick ash on the hill there was no ash under the 

 Raeburn Shale where it was to be expected. Binns 

 Hill had been a very small volcano, one of a group 

 that emitted showers of ash after the formation of 

 the Houston and Two Feet Coal seams over a district 

 extending southward about seven miles. Under the 

 whole district and below the Burdiehouse Limestone 

 there was a large intrusive basalt sill, and Binns Hill 

 and other small local ash-necks seem to have acted 

 as geological safety-valves by which imprisoned gases 

 escaped and blew up part of the fluid eruptive rock 

 in the form of fine dust and ashes. 



Paris. 

 Academy of Sciences, December 27, 192 1. — M. Georges 

 Lemoine in the chair. — The president announced the 

 death of Prof. Schwarz, correspondant for the sec- 

 tion of geometry. — E. Borel : Quasi-analytical func- 

 tions with real variables. — W. Kilian : A problem of 

 the tectonic of the sub-Alpine chains of Dauphin^. — 

 C. E. Guillaume : Recent fundamental determinations 

 and verifications of the standard metres. Slight 

 elongations in the lengths of the working standard 

 metres of the International Bureau have been proved. 

 The cause of the change is not clear, but is possibly 

 due to the effects of cleaning. Recent determinations 

 of the coefficients of expansion of the bars have proved 

 a small error in the opposite direction, and at the 

 present time these errors compensate each other at 

 about 15° C. — M. Gevrey : The determination of 

 the integrals of partial differential equations, order 

 2p, and m variables, admitting a multiple family of 

 characteristics of order p. — G. Bertrand : Fredholm's 

 equation and static masses of the first kind. — M. 

 d'Azambuja : A mode of graphical representation of 

 the filaments of the upper layer of the solar chromo- 

 sphere.— J. Villey : The adiabatic liquefaction of fluids. 



