412 



NA TURE 



[August 23, 1894 



expresses an ever-changing condition of equilibrium between 

 the crystal and the mother liquor. It does not take place by the 

 deposition of parallel plane layers ; new faces are constantly de- 

 veloped : since these succeed one another per salltim they 

 doubtless obey the law of rational indices, though not that of 

 simple rational indices. From the mutual inclinations of these 

 vicinal faces it is possible to calculate with absolute accuracy 

 the angle of the faces to which they symmetrically approximate. 

 This angle is found to be that of the regular octahedron 

 70° 313'. The octahedron angle of alum is not, therefore, as 

 appeared from the observations of Pfaff and Brauns, subject to 

 any variilion. 



Mr. Howard Fox described a remarkable rock which occurs 

 at Dinas Head in Cornwall, between a greenstone and a slate, 

 and apparently intruded upon by the former. It has the com- 

 position of albile felspar, with as much as lo per cent, of soda, 

 and is like the keratophyres in composition as well as in the 

 possession of concretionary and spherulitic structures. The 

 nodules and spherulites stand out as the rock weathers, and the 

 latter are shown by the microscope to consist of blades of albite 

 radiating round centres of cryptocrystalline material. On the 

 other hand, the rock might belong to the altered sediments 

 called adinoles, of which some, in the Harz, yield 7.5 per cent. 

 of soda, and with this the field evidence and the presence 

 of idiomorphic crystals of ferriferous carbonate appear to agree. 

 Mr. \V. \V. Watts exhibited photographs o( a stack of Kcuper 

 sandstone at the Peakstones, near Alton, Staffordshire, which, he \ 

 claimed to have proved, owed its resisting power to the existence 

 of almost vertical planes in the rock cemented by the deposit of 

 barium sulphate. These planes strike along a prominent ridge 

 between two valleys, and at the end of it is the projection of 

 the Peakstones rock. Other cases in which basement beds of 

 the Keuper sandstone are similarly cemented were quoted by 

 the author. 



Amongst the papers dealing with Oxfordshire geology, that 

 by Prof. Green demands attention first. In it he described the 

 sections displayed at Fawler and Stoncsfield, Shotover, Faring- 

 don, Culham, and Swindon. The thinness of the Upper Lias at 

 Fawler was remarked upon, and a curious case of contempo- 

 raneous erosion in the Forest Marble described ; the peculiar 

 character of the iron-sands was explained by their having been 

 deposited in a long strait, in which Faringdon was a sheltered 

 bay, suited for the growth of the organisms which here make 

 up almost the whole deposit. In the section at Culham, 

 which shows Gault resting directly on Kimmeridge or Portland 

 limestone, the denudation of the iron-sand was described as a 

 local phenomenon, it being found in full force at another section 

 hard by. The excavations at Stonesfield, carried out by Mr. 

 Walfotd, were the subject of a report by him, in which be showed 

 that about 30 feel of limestone with clay seams, presenting 

 on the whole the aspect of the great oolite, occurred beneath 

 the "slate" bed. He intends to continue his excavations in 

 order to determine the relationship of these deposits to the 

 Chipping Norton limestone and iheClypeus grit of the Oxford- 

 shire Inferior Oolite. In another paper the same author points 

 out that the terraced hill slopes occur in one geological line in 

 Oxfordshire, the outcrop of a band of micaceous marl in the 

 Middle Lias just below the "red rock bed." The water pene- 

 tralt» from above where the Upper Lias has been stripped oft' by 

 denudation and fillers through to the top of the clay of the 

 margaritalui zone, where it makes its escape. The saturated 

 marls arc continually creeping down hill, and, in doing so, give 

 rise to the terraces. 



Prof. W. Boyd Dawkins endeavoured to trace the submerged 

 folds of palaeozoic rocks under the mantle of newer formations in 

 Oxfordshire, by means of the principle originally laid down by 

 Godwin-Austen and elaborated by Bertrand in recetit papers, 

 that the great pre-carboniferous folds form lines of weakness, 

 along which the upper skin of later rock wrinkles and cr.icks. 

 The northern rim of the South Wales syncline, which contains 

 the coal-basin, wa< traced eastwards through the Forest of 

 Dean, the partially covered fields north of the Men- 

 dips, through Gloucester, Blenheim, Kirtlinglon, (Tuainton, 

 Bishop's Slortford, Braintrce, and Colchester. From 

 thi> it is reasonable to infer that coalfields will be found in the 

 area between this line and that from the Mendips to Hythe. 

 One •uch the author claimii lo have been discovered at Burford, 

 ics that further investigation should be carried on, 

 in the neighbourhood, lo set at rest the question 

 J...-. ..11 vturkable coals occur in this syncline. Three other 

 papers by the same author dealt with evidence from borings. 



NO. 1295, VOL. 50] 



The first drew attention to a seam of oolitic iron ore (grains of 

 hydrated oxide embedded in calcium and iron carbonates) of 

 Kimmeridgian age, met with at the Dover boring. The second 

 dealt with the Permian strata of the north of the Isle of Man, 

 consisting of 913 feet of red Roth-liegende sandstone, followed 

 by 455 feet of calcareous conglomerates and breccias, which 

 were correlated with the magnesian limestone ; these rocks 

 form a connecting link between those of Cumberland and North 

 Ireland. The third communication described three borings in 

 the north of the same island, one of which had penetrated 33 

 feet of salt-bearing marls apparently at a greater depth than 

 450 feet from the surfaces : the Triassic sandstones and saliferous 

 marls again present another link between Carrickfergus .ind 

 the F.nglish coast. A paper by Prof. Bonney instituted a com- 

 parison between the pebbles in the trias at Cannock and Bud- 

 leigh Salterton, as a result of which he concluded that those of 

 Budleigh must have come from the south-west, but that similar 

 fraginental rocks fringed the ancient western land in localities 

 far apart. 



Sir Archibald Geikie corroborated Heddle's identification of 

 the Pitchstone of Hysgeir, an island about eighteen miles west 

 of Eigg, with that of the latter island. This lava, which flowed 

 into a river channel sloping from east to west, is exactly like 

 that of the Scuir of Eigg, but unfortunately its base cannot 

 be seen. The old river channel would be at least 20 miles 

 long, with a fall of perhaps as much as 35 feet in a mile. 

 Gravels containing masses of volcanic rocks (some of them pos- 

 sibly thrown direct from volcanoes), with water-worn blocks 

 of Torridon sandstone, grit, quartzite, and other rocks, rapidly 

 thinning out or passing into fine tuft' or volcanic mudstone, are 

 to be found in the islands to the north of Hysgeir, interca- 

 lated at various horizons in the bedded basalts, and have doubt- 

 less been formed by the flooding and torrential action of 

 contemporaneous rivers. 



A joint discussion on the plateau implements of Kent, 

 held by Sections C and H, was opened by Prof. Rupert Jones, 

 who agreed with Prof. Prestwich that the implements were of 

 human origin and dated back to an ancient time when the 

 physical geography of the Weald was very difterent from its 

 character to-day. Mr. Whitaker followed with a paper, in 

 which he stated that he did not consider the plateau gravels so 

 ancient as had been supposed by other authors, but that part of 

 the deposit, at any rate, was a residuum which had grown where 

 it stood, and is still growing, so that implements in it might be of 

 almost any age. He further stated that he could find no evi- 

 dence to connect men with preglacial or even glacial times. 

 Amongst the other speakers were Mr. Montgomerie Bell, Sir 

 John Evans, Dr. H. Hicks, Prof. Boyd Dawkins, General Pitt- 

 Rivers, Sir Henry Howorth, Mr. Clement Reed, and Lieut. - 

 Colonel Godwin-.\usten. 



The more important pala:ontological communications included 

 Prof. Rupert Jones's eleventh report on Paljeozoic Phyllopoda, 

 Mr. Laurie's second report on the Eurypteridsof the Pcntlands ; 

 recording the obtaining of a large amount of material from which 

 important results are to be expected ; Dr. Traquair's pre- 

 liminar)' notice of a new fossil fish from the upper Old Red 

 Sandstone of Elginshire ; Mr. Jefts' descriptions of fornix of 

 Saurian footprints from the Cheshire Trias, some of which were 

 new, while apparently none of them could be referred to any 

 known species of Labyrinthodont ; and Dr. Hicks's conclusion 

 that the original home of the earliest forms of animal life was 

 at some point in the Atlantic. Mr. Montagu Browne's third 

 paper on Rhretic Verlebrala, in which teelh of " Saurichthyan" 

 type were described in the same jaws as Labyrinthodont teeth, 

 proving that the remains attributed lo Saurichlliys must be 

 assigned lo Labyrinlhodonts, Plesiosaurus, llybodus, and Gyro- 

 lepi-, also called attention to remains of Rysosteus, Metoposaurus 

 or Trematos.aurus (?), and Dinosauria. 



The consecration of Monday to pleistocene geology has almost 

 become an institution, probably because, although now facts of 

 consequence may not have been discovered within the year, at 

 Ica-st one new inictprelalion of them, or a new theory founded 

 on some of them, can always be relied upon. The day was 

 opened by Mr. Hell's report on Ihe well and borings at Chapelhall, 

 near Ainlrie, which completely proved that there was now no 

 shelly clay lo be found in the well or in borings in its inimcli.ilc 

 neighbourhood. Mr. Kendall followed with a report on Ihe 

 boulders examined and collected during the year. 



Dr. Hicks next endeavoured lo prove that Ihe stratified 

 gravels, .sands, and clay of Ihe plateaux of Hendon, Finchley, 

 and Whetstone, which arc covered by chalky boulder clay, had 



