472 



NA TURE 



[February i8. 1909 



owes its relief to denudation, acting on a plateau of 

 Cretaceous limestone and andesite, on which lava-flows 

 of basalt and rhyolite, with additional andesite, have 

 broken out. Important post-Cretaceous intrusions of 

 granite occur. The broad, enclosed basins of the plateau, 

 which are well illustrated, became filled up by debris, 

 largely wind-borne, and sandstones and conglomerates 

 arose which almost obliterated the original relief. The 

 present tendency is still towards the filling of such basins 

 by the crumbling of outstanding relics of the older surface 

 under the action of an arid type of denudation ; but rivers 

 have cut modern canons through the mass, and are pro- 

 ducing a new series of relief-features. It is interesting 

 to note (p. 422) that hanging valleys have been left in the 

 caiion of the Aros " by the more rapid cutting done by 

 the great stream." 



Mr. A. Gibb Maitland chose as the subject of his presi- 

 dential address to the Australasian Association for the 

 .Advancement of Science in 1907 " The Geology of Western 

 .Australia." This address forms a convenient summary of 

 rrcent work, now that it has been published by Mr. Bris- 

 low, Government printer in .Adelaide. Attention is directed 

 <p. 10) to the attractions offered by the Cambrian beds 

 of the Kimberley district, from which Hardman gathered 

 an unlocalised (jlenellus in 1883. The glacial boulder-bed 

 cast of the Kennedy Range (p. 16) is of early Carbon- 

 iferous age. Laterite, in part pisolitic, occurs throughout 

 Uestern Australia (p. 24), and is recognised as resulting 

 from the decomposition and re-consolidation of the under- 

 lying rocks in situ. These rocks are commonly granites. 

 Secondary silica converts some types of the laterite into 

 quartzitcs ; others pass over into bau.\ite. Here once more 

 we are in face of the most interesting problem of w'eather- 

 ing presented to us in the tropics. The laterite has been 

 cut through by denuding agents, and some of it may be 

 of early Cainozoic age, while in other places it is still 

 forming. 



.Among papers dealing with special systems rather than 

 with regional geology we may note one by Messrs. W. G. 

 Miller and C. W. Knight on the Grenville Hastings un- 

 conformity (Sixteenth Report, Bureau of Mines, Canada, 

 1907, p. 221), in which it is urged that the Hastings series 

 in Ontario and Quebec has an independent position, being 

 unconformable to the underlying Grenville series, and not 

 merely an altered portion of that scries. The Laurentian 

 gneiss is intrusive in the Keewatin series and in the over- 

 lying Grenville scries in south-eastern Ontario. The 

 Hastings series is styled Huronian by the authors. 



Sir T. H. Holland (Records Geol. Surv. India, vol. 

 xxxvii., 1908, p. 129) shows that the Blaini formation of 

 Simla, in which he now finds well-striated boulders, need 

 no longer be correlated with the Talchir beds, but may 

 be much older, since glacial conglomerates are known 

 from various horizons. The unfossiliferous sediments 

 below it, hitherto regarded as Permian or older, may be 

 actually as old as the pre-Cambrian, and may be classed 

 with the author's Purana beds of the peninsular area. 



In the same Records, vol. xxxvi. (1907), p. 23, Mr. 

 H. H. Hayden discusses the age of the Gangamopteris 

 beds of Kashmir, and furnishes good photographs of their 

 occurrence in the field. These beds are " not younger 

 than upper Carboniferous," since equivalents of the 

 Kcnestella-shales of Spiti overlie them. 



A very interesting paper on desert conditions and the 

 origin of the British Trias was contributed by the late 

 Mr. J. Lomas to vol. x. of the Proceedings of the Liver- 

 pool Geological Society (1907), p. 172. Personal observa- 

 tions in Africa \vere utilised, and the author lost his life, 

 as already recorded in Nature (vol. Ixxix., p. 226), while 

 extending his researches in an area from which he hoped 

 to gather much. Prof. Bonney, who has so long studied 

 the Triassic pebble-beds, has commented on Mr. Lomas 's 

 lonclusions in the Geological Magazine for 1908. Our 

 knowledge of the marine Trias of Europe is increased by 

 Dr. F. V. Kerner, who publishes a considerable paper on 

 the southern border of the Svilaia planina in Dalmatia 

 (Vcrhaiull. d. k.k. geol. Reichsanslalt. IQ08. pp. 2^9-289'). 

 In the unnermost zone there are reefs formed by calcareous 

 alija', with_ intervals of ordinary sediments between them, 

 where dr-tritus from earlVr volcanic rocks was washed in 

 among the limestone-building organisms. 

 NO. 2051, VOL. 79] 



Coming to much more recent times, Herr B. Stiirtz, of 

 Bonn, has made a detailed study of the " Rheindiluvium " 

 from Bingerbruck, near Mainz, downwards to the Nether- 

 lands (Verltandl. d. natiirhist. Vcrcins der preuss. Rhein- 

 lande u. Westfalens for 1907, published 1908, pp. 1-91). 

 He does not seem to take into consideration the older 

 extension of the alluvium of the Rhine to the English 

 coast, whicli many authors have looked on as a feature 

 of late Pliocene times. He regards the old delta as 

 beginning near the Ahr, midway between Coblenz and 

 Bonn, at a time when the stream-bed was some 150 metres 

 higher than at present. A broad plain dropping seaward 

 to the area of the Netherlands allowed the river to wander 

 in various arms, much as it does now in Holland, and 

 these arms have left their traces in high-level " diluvial " 

 gravels. The present valleys of the main stream and of 

 its tributaries must have been deepened by 100 to 200 

 metres in Pleistocene and recent times. The effects of the 

 damming up of the waters by the Scandinavian ice-front 

 are discussed. The higher deposits of loss are, however, 

 attributed to wind-action, while others were laid down in 

 • glacial lake between the uplands and the ice. 



G. A. J. C. 



A REM.iRK.lBLE DEVELOPMENT IN m 



X-RAY APPARATUS. 

 'T'HE old induction-coil seems likely to have a serious 

 rival in the new apparatus which Messrs. Newton 

 and Co., of Fleet Street, are showing. This is the 

 " Snook " Rontgen apparatus. The machine consists of a 

 motor converter driven from the continuous current mains, 

 and supplying an alternating current to a step-up trans- 

 former. This transformer is immersed bodily in a 

 galvanised iron tank filled with an insulating oil, the whole 

 being hermetically sealed. The voltage at the secondary 

 terminals of this transformer amounts to as much as 

 70,000-100,000, and can be regulated as required by means 

 of an adjustable resistance in the primary circuit. 



The most important adjunct is a mechanical rectifier, 

 consisting of a rotating commutator of special design 

 carried on the axle of the motor converter ; thus it cannot 

 get out of step, and, what is perhaps of as great import- 

 ance, it requires no attention. The commutator when 

 once adjusted in proper phase produces a very nearly 

 unidirectional current, although, of course, perfection in 

 this respect is unattainable, as will be realised when it is 

 remembered that the current from the converter cannot be 

 a simple harmonic one. Be this as it may, the rectification 

 is very successfully made, and the simplicity of the device 

 commends it when compared with the very troublesome 

 valve tubes which must so frequently be employed for 

 heavy X-ray work. 



With regard to the efficiency, a current of 2"; amperes 

 at 200 volts in the primary circuit yields 60 milllamperes 

 or more through an X-ray tube of 3 or 4 inches spark. 

 Having inspected the apparatus while in action, we may 

 state that we consider it to be a most efficient addition 

 to the numerous arrangements available to the present-day 

 worker in X-rays. 



RECENT PAPER.S ON MARINE ANIMALS. 

 A MONG papers on various groups of marine animals 

 -'*" in serial and other publications which have recently 

 reached us, reference may first be made to a fasciculus 

 of " Illustrations of the Zoology of the Indian Survey Ship 

 Investigator," containing plates devoted to new and other 

 species of fishes, entomostracous crustaceans, and molluscs. 

 In addition to certain deep-sea forms, the fishes include 

 two species of skate, described by Dr. R. E. Lloyd in 

 1906, several kinds of stalked barnacles are figured, and 

 the molluscs include seven species, described by Mr. E. A. 

 Smith in the year already mentioned, of which the shells 

 are for the first time depicted. 



Reverting to fishes, we find Messrs. Gilchrist and Ward- 

 law Thompson contributing to the second part of vol. vi. 

 of the .Annals of the South African Museum one paper on 

 the local Blenniidae and another on various species from 

 the Natal coast. The blennies have hitherto been very 



