May 2, 1872J 



NATURE 



17 



Cambrian group. Murchison asserted and illustrated by sections 

 tlie unvarying fact that iiis Llandeilo flag was superior to the 

 Upper Cambrian group. There was no difference between us 

 until his Llandeilo sections were proved to be wrong." (Philos. 

 Mag. IV. viii. 506.) That there must be a great mistake in Sedg- 

 wiclv's or in Miirchison's sections was evident, and the Govern- 

 ment surveyors, wliile sustaining the correctness of those of 

 Sedgwick, have shown the sections of Murchison to have been 

 completely erroneous. 



Tlie first step towards an exposu'e of the errors of the Silurian 

 sections is, however, due to Sedgwick and McCoy. In order 

 better to understand the present aspect of the question, it will be 

 necessary to state in a few words some of the results which have 

 been arrived at by the Government surveyors in their studies of 

 the rocks in question, as set forth by Ramsay in the Memoirs of 

 the Geological .Survey. In the section of the Berwyns, the thin 

 bed of about twenty feet of Bala limestone, which (as originally 

 described by Sedgwick) they hive found outcropping on both 

 sides of the synclinal chain, is shown to be intercalated in a vast 

 tliickness of Caradoc rocks ; being overlain by about 3,300 and 

 underlain by 4,500 feet of strata belonging to this formation. 

 Beneath these are 4,500 feet additional of beds described as 

 Llandeilo, which rest unconformably upon the Lingula-flagsjust 

 to the west of Bala ; thus making a thickness of over 12,000 feet 

 of strata belonging to the Bala group of Sedgwick. A small 

 portion of rocks referred to the Wenlock formation occupies the 

 synclinal above mentioned. (Memoirs, III. part 2, 214,222.) 

 The second member, in ascending order, of the Silurian system, 

 to which the name of Caradoc was given by him in 1S39, was 

 originally described by Murchison under the names of the Hor- 

 derly and May Hill sandstone. The higher portions of the 

 Caradoc were subsequently distinguished by the Government sur- 

 veyors as the Lower and Upper Llandovery rocks ; the latter 

 (constituting the May Hill sandstone, and known also as the 

 Pentamerus beds) being by them regarded as the summit of the 

 Caradoc formation. In 1852, however, Sedgwick and McCoy 

 showed from its fauna that the May Hill sandstone belongs rather 

 to the overlying Wenlock than to the Caradoc formation, and 

 marks a distinct pakeontological horizon. 



This discovery led the geological surveyors to re-examine the 

 Silurian sections, when it was found by Aveline that there exists 

 in Shropshire a complete and visible want of conformity between 

 the underlying formations and the May Hill sandstone ; the latter 

 in some places resting upon the nearly vertical Longmynd rocks, 

 and in others upon the Llandeilo Hags, the Caradoc proper or 

 Bala group, and the Lower Llandovery beds. Again, in South 

 Wales, near Builth, the May Hill sandstone or Upper Llandovery 

 rests upon Lower Llandeilo beds ; while at Noeth Giug the 

 overlying formation is traced transgressively from the Lower 

 Llandovery across the Caradoc to the Llandeilo. These impor- 

 tant results were soon confirmed by Ramsay and by Sedgwick. 

 (Ibid, 4, 236). The May Hill sandstone often includes, near its 

 base, conglomerate beds made up of the ruins of the older for- 

 mation. To the north-east, in the typical Silurian country, it is 

 of great thickness and continuity, but gradually thins out to the 

 south-west. There exists, moreover, another region where not less 

 curious discoveries were made. About forty miles to the eastward 

 of the tyjiical region m South Wales appear some important areas 

 of Silurian rocks. These are the Woolhope beds, appearing 

 through the Old Red Sandstone, and the deposits of Abberley, 

 the Malverns and May Hill rising along its eastern border, and 

 covered along their eastern base by the newer Mesozoic sand- 

 stone. The rocks of hese localities were by Murchison in his 

 " Silurian System" described as offering the complete .sequence. 

 When however it was found that his Caradoc included two un- 

 conformable series, examination showed that there was no repre- 

 sentative of the older Caradoc or Bala group in these eastern 

 regions, but that the so-called Caradoc was nothing but the 

 Upper Llandovery or May Hill sandstone. The immediately 

 underlying strata, which Murcliison had regarded as Llandeilo, 

 or rather as the beds of passage from Llandeilo to Cambrian, and 

 had compared with the north-west passage of the Caermarthen- 

 shire sections (Syl. .Sys. 416), have since been found to be much 

 more ancient deposits, of Middle Cambrian age, which rests 

 upon the crystalline hypozoic rocks of the Malverns, and 

 are uncomformably overlain by the May Hill sandstone. 

 We shall again revert to this region, which has been carefully 

 studied and described by Prof. John Phillips. (Mem. Geol. 

 Sur. II., part i.) T. Sterry Hunt 



(To be continued)] 



SCIENTIFIC SERIALS 



The Rc'viu- Sckntifique, Nos. 33—42. The first article in 

 these numbers is by Prof. Huxley, on Yeast. — The conclusion is 

 arrived at of M. de Quatrefages' course of lectures on Anthro- 

 pology, at the Museum of Natural History at Paris. — M. de 

 Fonvielle contributes an article on Balloon Observations. In 

 No. 34. M. Leon Le Fort, Professor to the Faculty of Medicine 

 at Paris, furnishes an account of military surgery in the Austrian 

 army. — Among the contributions from foreign sources is are- 

 port of M. Vogel's spectroscopic observations of the planets 

 made in 1S71 at the observatory of Bothkamp. — No. 35 contains 

 an interesting lecture, delivered at the University of Fnberg-in- 

 Brisgau, by M. Ecker, on the struggle for existence in the 

 character and in the life of nations. — In No. 36 is commenced 

 a report, continued in subse<]uent numbers, of M. Claude Ber- 

 nard's course of lectures at the College of France on Animal 

 Heat. A translation is given of a paper by Prof. Harting, of 

 Utrecht, on the artificial production of organic calcareous for- 

 mations. There are also reports of the proceedings of English 

 and other foreign scientific societies. — In No. 37 the most 

 interesting paper is one by Dr. Onimus, on the consecutive 

 phenomena attendant on the removal of the brain, and on the 

 movements of rotation, illustrated with drawings of frogs and 

 birds, on which the operation had been performed, to show 

 the action. — No. 3S contains a report of Prof. Virchow's ad- 

 dress to the Congress of German Naturalists and Physicians at 

 Rostock, on Science in the national life of Germany. Sir 

 William Thomson's paper on the Size of Atoms is translated from 

 an early number of this journal. M. Papillon has an article in 

 support of .M. Wurtz's aphorism, "Chemistry is a French science, 

 constituted by Lavoisier," in reply to English and German at- 

 tacks. — No. 39 commences with an important article by M. P. 

 Lorain, on Reform in the Higher Instruction. A translation is 

 given of M. R. Woll's lecture at the University of Zurich on 

 Solar Spots, and of Neuinayer's paper contributed to the 

 Vienna (■. /■. Gcolo'^lschc Reichsanstalt on the Jurassic Basins. — 

 In No. 40 M. Le Fort supplements his previous paper by an 

 additional one on Military Surgery in ihe Prussian army. This 

 and the following number are partially filled with further reports 

 of the Rostock meeting of German naturalists and physicians. — 

 In No. 41 we find also a lecture by M. Lereboullet at the School 

 of Military Health iat Montpellier on the Spinal Column.— No. 

 42 contains a report of M. Blanchard's address to the Annual 

 Congress of the Learned Societies of the Departments at the 

 Sorbonne. M. Paul de Saint Robert contributes a paper whh 

 the suggestive title, " Qu'est ce que la force ? " There are also a 

 number of reports of the proceedings of foreign societies. 



The Journal of Botany for April commences with an interest- 

 ing article by Prof. Babington on the Anacliaris alsinastrnm or 

 Canadian water-weed. He shows clearly that there are two 

 series of plants closely resembling each other in appearance, of 

 which one series has perfect triandrous flowers, and the other 

 has incomplete dicecious flowers, of which the males are nearly 

 or quite sessile, and have the curious habit of becoming detached 

 when the pollen is ripe, and floating freely about on the surface 

 of the water, and shedding their pollen there. To the first 

 series belongs the Elodca of South America ; to the second, 

 Anao/iaris and Hydrilla. Anacliaris would therefore appear to 

 be the true genus to which the English (introduced) plant be- 

 longs, as given by Hooker, but not by Bentham and Syme. — Mr. 

 Baker gives one of his useful synoptical revisions of the Cape 

 species of Ant/icricnm ; and Prof. Thiselton Dyer a history of 

 the substance known as "Australian Caoutchouc," and a valu- 

 able account of the mode of germination of Trop.coluni, which 

 is characteristic rather of endogens than of exogens. 



Annalcn dcr Chcinic nnd Pharntacie, January 1S72. This 

 number commences with a paper by Max Ascher on the trisub- 

 stitution derivation of benzine ; this is an attempt to estabhsh 

 the constitution of some of these bodies, but at present, how- 

 ever, it has not been entirely successful. — The next paper is by 

 Linnemann and Zotta "On the reduction of formic acid to 

 formaldehyde and methyl alcohol ; " the authors followed exactly 

 the same process as was described by Lleben and Rossi some 

 time since, and which has already been noticed in these pages. 

 The next three communications are by Linnemann " On 

 normal propyl alcohol, its compounds and its conversion into 

 isopropyl alcohol." The author prepared the normal alcohol in 

 two ways — by the action of nascent hydrogen on propionic 

 anhydride, and by obtaining the aldehyde by distillation of calcic 



