May 9, 1872 J 



NATURE 



35 



geologists "would have accepted the Lower Sihirian classification 

 and nomenclature, had they known that the physical or sectional 

 evidence upon which it was based had been from the first posi- 

 tively misunderstood." Feeling that his own sections weie, as 

 has since been fully established, free from error, Sedgwick natu- 

 rally thought his name of Upper Cambrian should prevail for 

 the great Bala group. Hence the long and embittered discussion 

 that followed, in which Murchison in many respects occupied a 

 position of vantage as against the Cambridge professor, and 

 finally saw his name of Lower Silurian supplant almost entirely 

 that of Upper Cambrian given by Sedgwick, who had lirst 

 rightly defined and interpreted the geological relations of the 

 group. 



In a paper read before the Geological Society in June, 

 1843 (Proc. Geo!. Soc. iv. 212-223), when the perplexity 

 in which the relations of the Upper Cambrian and Silu- 

 rian rocks were involved had not been cleared up by the dis- 

 covery of Murchison's errors in stratigraphy, Sedgwick proposed 

 a comproaaise, according to which the strata from the Bala lime- 

 stone to the base of the Wenlock were to take the name of 

 Cambro-Silurian ; while that of Sihirian should be reserved for 

 the Wenlock and Ludlow beds, and for those below the liala 

 the name of Cambrian should be retained. The Festiniog group 

 (including what were subsequently named the Lingula fl-jgs and 

 the Tremadoc slates) would thus be Upper instead of Middle 

 Cambrian, the original Upper Cambrian being henc>:forth 

 Cambro-Silurian ; it being undeisiood ihat, wherever the dividing 

 line might be drawn, all the groups above it should be called 

 Cambro-Silurian, and all those below it Cambrian. This com- 

 promise was rejected by Mutchison, who in the map accompany- 

 ing the first edition of his " Siluria," in 1S54. extended the 

 Lower Silurian colour so as to include all but the lowest division 

 of the Cambrian, viz., the Bangor group. When, ho a ever, the 

 relations of Upper Cambrian and Silurian were made known by 

 the discoveries of Sedgwick and the (juvernment suivevors, this 

 compromise was seen to be uncalled for, and was withdrawn in 

 1854 by Sedgwick, who reclaimed the name of Upper Cambrian 

 for his Bala group. 



In June 1S43, Sedgwick proposed that the whole of the fos- 

 siliferous rocks below the horizon of the Wenhick should be 

 designated Protozoic, and on Nov. 29, 1S43, presented to the 

 Geological .Society an elaborate paper on the Older Pateoz ic 

 (Protozoic) Rocks of North Wales, with a coloured geol. 'gic.il 

 map. This paper, which embodies! the re-ulis of the researches 

 of Sedgwick and Salter, was not. however, published at length, 

 but an abstract of it was prepared by Mr. Warburt^n, then pre- 

 sident of the society, with a reduced copy of the map (Proc. 

 Geol. Soc. iv. 212 and 251-268 ; also Geol. Jour. i. 5-22) In 

 this map of Sedgwick's three divisions were es-ablished, viz , the 

 hypozoic crystalline schists of Caernarvonshire, the Protozoic, 

 and the .Silurian. On the legend of the reduced map, as pub- 

 lished by the Geological Society, thrse later names were a ttrcd 

 so as to read " Lower Silurian (Prutozoic) " and " Upper .Silu- 

 rian." These changes, in conforniiiy with the nomencla'uie nt 

 Murchison, were, it is unnecessary to say, marie without the 

 knowledge of Sedgwick, who did not inspect the reduced and 

 altered map until it was appealed to as .in evidence that he had 

 abandoned his former ground, and had recognised the equivalency 

 of the whole of his Cambrian with the Lower .Silurian of Mur- 

 chison. The reader will sympathise with the indignation wi'h 

 which Sedgwick declares that his map was *' most unwarrantably 

 tampered wiih," and will, moreover, learn with surprise that an 

 inspection of the proof sheets of Warburtim's abstract of Sedg- 

 wick's paper was refused him, notwiihs'anding his rep^atcd 

 si'licitatiuns. The story of all thjs, and finally of the refus.al to 

 print in the pages of the Gcv/o^it-ii/ yoiin/ii/ the reclamations of 

 the venerable and aggrieved author, make altogether a painful 

 chapter, which will be found in the I'hilos. Ma-^adne for 1S54 

 (IV. viii. pp. 301-317, 359-370, and 483-506), and more fully in 

 the "Synopsis of British Paloiozoic Hocks," which forms the 

 introduction to McCoy's "British Pateozoic Fos-ils." 



In connection with this history it may be mentioned that in 

 March 1845 Sedgwick presented to the Geological Society a 

 paper on the Comparative Classification of the Fossiliferous 

 Rocks of Noith Wales and those of Cumberland, Westmoreland, 

 and Lancashire, which appears also in abstract in the same 

 volume of the Ccolos^ical J onrnal that contains the abstract of the 

 es<ay and the map ju^t referred to (i. 442). Tfiat this abstract 

 also is made by another than the author is evident from such an 

 expression as "the author's opinion seems to be grounded on 



the following facts," &c. (p. 448), and from the manner in which 

 the terms Lower and Upper .Silurian are applied to certain 

 fossiliferous rocks in Cumberland. Vet the words of this ab- 

 stract are quoted with emphasis in " Siluria" (ist ed , 147), as 

 if they were Sedgwick's own language, recognising Murchison's 

 Silurian nomenclature. 



W.—MiddU ami Loiver Cambrian 



I.nvestigations in continental Europe were, meanwhile, prepar- 

 ing the way for a new chapter in the history of the lower palaeo- 

 zoic rocks. A series of sedimentary beds in Sweden and Norway 

 had long been known to abound in singular petrifications, some 

 of which had been examined by Linna;us, who gave to them the 

 name oi KiUoiiiolitlii. They were also studied and described by 

 Wahlenherg and by Brongniart, the latter of whom, from two 

 varieties ot the Entoinolillnis paraaoxus, Linn, established in 

 1822 two genera, Paradoxiifcs and Agiii'sliis. In 1826 appeared 

 a memoir by Dalman on the PaL-eada;, or so-called Trilobites ; 

 which was followed, in 1828, by his classic work on the same 

 subject (" Ueber die Pal^'aden oder so-genannten Trilobiten, "410, 

 with six plates, Leipsic). In these works were described and 

 figured, among many others, two genera — Oleniis, which included 

 Paradox ides Brongn. and Ballns, including Agiwsltts of the 

 same author. Meanwhile, Hisinger was carefully studying the 

 strata in which ihe^e Trilobites were found in Gothland, and in 

 the same year (1828) published in his Anteckningar, or Notes 

 on I he Physical and Geognostical Structure of Norway and 

 Sweden, a coloured geological map and section of these rocks as 

 they occur in the county of .Skaraborg, where three small cir- 

 cumscribed areas of nearly horizontal fossiliferous strata are 

 shown to rest upon a floor of old crystalline rocks, in some parts 

 granitic and in other gneissic in character. The section and 

 map, as given by Hi-inger, show the succession in the principal 

 arer to be as follows, in ascending order : (i) granite or gneiss, 

 (2) sandstone, (3) alum-slates, (5) orthoceratite-limestones, (4) clay, 

 slates. By a curious oversight the colours on the legend are 

 wrongly arranged and wrongly numbered, as above ; for in the 

 map and section it is m^de clear that the succession is that just 

 given, and that the clay-slates (4) instead of being below, are 

 above the orthoceratite-limestones (5). 



In 1837 Hisinger published his great work on the organic 

 remains i^f S-»eden, entitled Lethiva Succica (410, with forty-two 

 pla es). In thi. he gives a tabular view, in descending order, of 

 the rock-formations, and of the various genera and species de- 

 scribrd. The rocks of the areas just no'iced appear in his fourth 

 or lowest division, under the head oi Forinationes Transitioiiis, 

 and arc divided as follows : — 



a. Strata calcarea recentiora Gottlandi.^. 

 /'. .Strata schisii aigillacei. 

 c. Strata schisti aluminaris. 

 (/. Strata calcarea andquiora. 

 I'. Strata sixi arenacei. 



The succession thus given was however erroneous, and pro- 

 bavly, like the mistake in the legend of the same author's map 

 just meniioned, the result of inadvertence, the true position of 

 the alum-slates (c) being between the older limestone (d) and 

 the basal sandstone (f). This is shown both by Hisingcr's map 

 ot 1828, and by the testimony of subsequent observers. In 

 Murchions work on the Geoh'gy of Russi . in Europe, published 

 in 1845. there is given (p. 15 ct scij.) an account of his visit to 

 this region in company with Prof Loven, of Christi,inia ; which, 

 with figures of the sections, is reproduced in the different 

 editio s of " Siluria." The hill of Kinnekulle, on Lake Wener, is 

 one of tr.e three aieas of transition rocks delineated on the mad 

 of Hisinger aliove referred to. Resting upon a flat region of 

 nearly vertical gneissic strata, we have according to Murchison, 

 (l) a fucoidal .sandstone, (2) alum-slates, (3) red orihocerati'e 

 limestone, (4) black graptolitic slates, the whole seties being 

 little over 1,000 ft. in thickness, and capped by erupted gre-n- 

 stone. Above these higher slates there are found in some parts 

 of Gothland, other limes'ones with orihoceratiies, trilobies. and 

 curals, the newer limestone strata (a) of Hisinger ; the whole 

 overlain by thin sandstone beds. These higher limestones and 

 sandstones contain the fauna of the Wenlock and Ludlow of 

 England ; while the lower limestones and graptoUtic slates afford 

 Calyiih-ih- Idiuiunhackii, Orl/iis calligyamtiia. and many other 

 species coinmun to the Bala group ot North Wales. The alum- 

 slates beliw these however comained, according to Hisinger, 

 none of the species then known in Bri ish rocks, but in their 

 stead five species of Olaiiis and two of Batliis {Agnostus), 



