May 13, 1875] 



NATURE 



23 



them Cambrian, and bidding Sedgwick, if he would retain 

 the latter name, to find some fossiliferous beds below. 

 This is followed by the complete dropping out of the 

 name in his " Russia ; " and when in after years a §eries 

 of Lower Fossiliferous beds were found, Murchison still 

 sought to include them under the title of Silurian. It is 

 astonishing that Sedgwick should for so long have failed 

 to perceive the drift of these changes— and when he did 

 at length arouse himself he found half his Cambrian 

 system gone, and not unnaturally felt that his friend had 

 " stolen a march on him." Such appears from the data 

 afforded by this work to be the true account of this con- 

 troversy. In late years, however, chiefly owing to the 

 labours of Mr, Hicks, much new light has been thrown 

 on the succession of faunas in these earliest rocks, and 

 it has been shown that by no means the greatest break 

 in life occurs at the base of the Llandeilo rocks as de- 

 scribed by Murchison ; and it is therefore probable that 

 the true limits of the two systems will have yet to be 

 re-adjusted under the light of the new facts. 



The " Silurian System " is a masterpiece of industry, 

 perseverance, and comprehensiveness, and will be a clas- 

 sical work so long as Geology is a science ; it is undoubt- 

 edly Murchison's magnum opus, and it led directly to 

 those other researches by which he has also contributed 

 so much to our knowledge. Thus it was, on being told 

 that plants had been found in Silurian rocks in Devonshire, 

 that he persuaded Sedgwick to accompany him there, 

 when they found that the so-called Silurians were really of 

 Carboniferous age — but on what did they rest? on a series 

 of rocks with a peculiar assemblage of fossils, which gave 

 them great difficulty at first, but which at last they recog- 

 nised as a new system, the Devonian, with which they 

 boldly classed the Old Red Sandstone, though no com- 

 munity of fossils had yet been proved. This last step, 

 however, was fully justified, by Murchison's finding in 

 Russia the fishes of the one associated with the shells of 

 the other, and thus the Devonian system was settled on a 

 firm basis. 



The received classification, however, of the Devonian 

 rocks was called in question by Prof. Jukes shortly before 

 his lamented death ; he assigned the greater part of them 

 to the Lower Carboniferous system, and Prof, Geikie con- 

 siders it to remain now an open question. He says : 

 " They who have given most attention to this part of 

 geology will probably most readily admit that, whether in 

 the way of contest or not, the question must be reopened ; 

 that the accepted classification is far from being satisfac- 

 tory, and that Jukes did a great service by boldly attack- 

 ing it, and bringing to bear upon it all his long experience 

 in the south of Ireland, which gave him an advantage 

 possessed at the time by hardly anyone else." Whatever 

 controversy, however, there may be on the classification 

 of particular rocks, there can be no doubt that there is a 

 distinct epoch of life between the Carboniferous and 

 Silurian, and this Murchison and Sedgwick together first 

 defined and established. 



It was for the study of the Silurian system, too, that 

 Murchison was led into Russia, and here it was that he 

 found that large development of rocks containing a special 

 fauna overlying the Carboniferous, to which he gave the 

 name of Permian, and which formed the subject of several 

 subsequent researches. 



We are greatly indebted to Murchison for the introduc- 

 tion of good names into Geology. It was he who first 

 proposed the use of geographical terms, so happily illus- 

 trated in " Silurian," which introduce no theory and no 

 incongruity, such as is involved in calling rocks " transi- 

 tion rocks," or speaking of the Old Red Sandstone as 

 represented by a clay. This method of nomenclature has 

 been widely adopted and is now almost universal, and it 

 has the further advantage of carrying with it information 

 as to the locality where the series is typically developed. 



The minor works of Murchison, in the shape of papers 

 and addresses during the time that these " systems " were 

 being worked out, were numerous, and, with the exception 

 of his " Geology of Cheltenham," almost entirely con- 

 fined to those Palaeozoic rocks that had now become so 

 familiar to him. But he brought forward now, not only 

 his own researches, but those of more humble workers 

 also, always giving them due credit. Amongst the most 

 remarkable of these were the discovery of the curious 

 crustaceans of a new type, now known as Eurypteridae, in 

 the Upper Silurian rocks of Lesmahagow, by Dr. Slimon. 

 Another was the discovery of fossils in the ancient crystal- 

 line rocks of the Highlands, by Mr. Peach, which led 

 ultimately to the last of the valuable series of labours that 

 Murchison performed. In the same category as the 

 above must be placed the publication of " Siluria," in 

 which he embodied from time to time, not only his own 

 original researches and additions to them, but the works 

 of all who had laboured in that field, by which the work 

 became at the same time less his own, and more compre- 

 hensive than the " Silurian System." 



Finally, in the chapter entitled "The Foundatio 

 Stones of Britain," Prof. Geikie gives an account 

 Murchison's last geological work, that of making out 

 the structure of the extreme north-west of Scotland, 

 and discovering there the oldest rocks in Britain. 

 Here, in 1858, he discovered three series of rocks, 

 each overlying the one below unconformably, and it 

 was in the upper of these three that Mr, Peach had found 

 Lower Silurian fossils. If, then, the second be the Cam- 

 brian, the lowest must be a series still older. To this he 

 gave the name of Fundamental Gneiss, but afterwards 

 classed it with the Laurentian system of Sir E. Logan, 

 which had been hitherto unrecognised in Britain. This 

 work, however, valuable as it is, is of a different kind to 

 that which made Murchison what he was — a master- 

 builder in Geology. 



His chief work consisted in uniting vast masses of rocks 

 stretching over miles of country, variously characterised 

 lithologically, and containing numerous different suites of 

 fossils, into large comprehensive groups ; in grasping the 

 features by which many minor periods are united into 

 single systems ; in laying down the broad outlines in 

 which the complete geological picture is to be traced. 

 This is the work wanted at the birth of a science ; it 

 requires a peculiar power of mind, possessed in large 

 degree by Murchison, who thus deservedly takes rank 

 among the founders of Geology. 



We leave Prof. Geikie's work with regret. Like him in 

 writing it, we live again in reading it, with this hero of 

 science ; and no one can rise from its perusal without a 

 deeper interest in the progress of knowledge, and espe- 

 cially of geology. A man of great power, thoroughly 



