126 



HARDWICKE'S SCIENCE-GOSSIP. 



discuss its value, and finally to summarise the ar- 

 guments which led Murchison to the opinion still 

 retained by the Survey. 



First, let us briefly examine the geological structure 

 of the range. The hills consist of a central ridge of 

 Syenite with much syenitic and granitoid gneiss and 

 diorite : on each flank are beds of schist which 

 become more and more brittle and contorted as we 

 approach the syenitic nucleus which is exposed at 

 many points, as at Keys End Hill and the valley of 

 the Whiteleaved Oak, and was passed through in the 

 Malvern and Ledbury Tunnel.* Resting very 

 unconformably upon these schists, we find on the 

 west of the Keys End Hill, the Hollybush Sandstone, 

 the basement bed of which contains pebbles of the 

 igneous rocks derived from the hills, the presence of 

 which proves that the sandstone is the more recent 

 formation. From its fossils {Trachyderma aiiti- 

 quissima, Salter, Scrpulites fistula, Holl, Obolclla 

 Phillipsii, Holl, Lingula squamosa, Scolitlnis and four 

 undetermined species), Dr. Hicks has correlated it 

 with his Festiniog beds (middle Lingula Flags). 

 This is the oldest fossiliferous bed in the district, and 

 it limits us to two possible theories as to the age of 

 the hills ; they may be Archean, or they may be 

 Lower Cambrian. 



With the above sketch in, at any rate, its main 

 points, most geologists would agree ; but here the 

 two paths diverge, the old school holding that the 

 hills were formed by the metamorphism of Longmynd 

 rocks into gneiss and schist by the intrusion of the 

 underlying syenite ; the Archeanists maintaining 

 that the rocks were deposited in some peculiar 

 manner in Pre-Cambrian times. 



The latter school found their case mainly on the 

 three following propositions : 1st (which would only 

 be advanced by the more thorough-going members 

 of the school) that as no Post-Archean regional 

 metamorphism is possible, these rocks being meta- 

 morphic are consequently Pre-Cambrian ; 2nd, that 

 even if we admit the possibility of Post-Archean 

 metamorphism, the period of time between the 

 Loncmynd and the Hollybush Sandstone would be 

 insufficient for the deposition of these strata, and 

 their alteration into gneisses ; 3rd, that the Malvern 

 rocks are similar to those from other Pre-Cambrian 

 areas. 



Let us briefly examine these arguments. The 

 truth of the first proposition most geologists would 

 deny in toto ; and while admitting the possibility 

 that many areas now considered metamorphosed 

 Cambrian may prove to be Archean (as has recently 

 been done by Geikie,f with the " Newer Gneiss " of 

 the Highlands), when one remembers how many 

 instances have been described of the passage of 

 sedimentary into schistose and gneissose rocks, and 



* f Symonds and Lambert on Strata exposed in Malvern and 

 Ledbury Tunnel. " Quart. Journ. Geol. Soc." vol. xvii. 

 "i" "Nature," vol. xxxi. pp. 29-34. (Nov. 13.) 



that its most enthusiastic adherents only claim that 

 it is supported by negative evidence — one cannot but 

 receive such an argument with great caution. Of 

 such instances are the fossiliferous schists of 

 Christiania,* the Liassic Mica schists of St. Gothard,f 

 and the passage in the Pyrenees so well described 

 by Fuchs,! of clay slate through Fruchtschiefer 

 chiastolite slate, andalusite schist, and Mica schist 

 into gneiss. 



The objection of lack of time cannot be accepted 

 when we remember that during the Lower Cambrian 

 era were deposited over 500 feet of the Menevian, 

 the 6000 feet of the Harlech Grits and the 20,000 feet 

 of the Longmynd : even if the gneiss and schists of 

 Malvern represent the whole of the Longmynd, we 

 have a period represented by the deposition of 6500 

 feet, and this would certainly seem ample for the 

 elevation of so small a chain of hills, when we bear 

 in mind that the gigantic ranges of the Alps, Andes, 

 and Himalayas were all elevated during the much 

 shorter system of the Miocene. 



In replying to the third argument, that from the 

 structure of the rocks, I need not here discuss the 

 possibility of correlating rocks by their mineralogical 

 composition. We need only note the great differences 

 as pointed out by Murchison between the fissile, 

 fine-grained syenitic gneiss of the Malverns, and the 

 thick-bedded coarse gneiss of the Highlands, which 

 differ in every respect save in the abundance of 

 hornblende. Nor do these rocks more resemble the 

 so-called Pre-Cambrian of St. David's. Dr. Calla- 

 way, whose fairness and moderation in a controversy 

 that has not been lacking in personalities command 

 our respect, and whose able and lucid series of papers 

 on the Malvern Hills, the Wrekin, Anglesey, and the 

 Highlands, have placed him in the front rank of 

 English Archeanists, says : § " The Malvern Series is 

 almost exclusively gneissic, foliation is well marked, 

 and hornblende abounds. In the St. David's area 

 gneiss is absent." He further points out the absence 

 at the latter place of schists, as the so-called " quartz 

 schists " of Hicks are really granitoids and quartzites. 

 {To be continued.') 



GOSSIP ON CURRENT TOPICS. 

 By W. Mattieu Williams, F.R.A.S., F.C.S. 



THERE appears to be fair reason for hoping that 

 the cattle plague will become, like small- 

 pox, an historical disease. Pasteur's method of vac- 

 cination has been successfully applied in India to 

 elephants, horses, asses, cows, buffaloes, and sheep. 

 I say " like small-pox " because the effect of vaccina- 



* Reusch, " Upper Silurian Fossils in Metamorphic Rocks of 

 Christiania. Universitets Programm, 1882." 

 + Ball's " Introduction to Alpine Guide," p. 74. 

 J C. W. C. Fuchs, "Neues jahrb. fur Miner," 1870, p. 742. 

 $ Callaway, "Quart. Journ. Geol. Soc." vol. xxxvi. p. 538. 



