Sept. 6, 1888] 



NA TURE 



449 



SECTION C. 



GEOLOUY. 



Opening Address by W. Boyd Dawkins, M.A., F.R.S., 

 P.G.S., F.S.A., Prokessok ok Geology and Pale- 

 ontology in Owens College, President 01 



Section. 



In taking the chair occupied twenty-four years ago in this 

 place by my honoured master, Prof. Phillips, I have been much 

 perplexed as to the most fitting lines on which to mould my 

 address. It was open to me to deal with the contributions to 

 our knowledge since our last meeting in Manchester in such a 

 manner as to place before you an outline of our progress during 

 the last twelve months. But this task, difficult in itself, is ren- 

 dered still more so by the special circumstances of this meeting, 

 attended, as it is, by so large a number of distinguished geo- 

 logists, assembled from nearly every part of the world for the pur- 

 poses of the Geological Congress. It would be presumptuous of 

 me, in the presence of so many specialists, to attempt to sum- 

 marize and co-ordinate their work. Indeed, we stand too near to 

 it to be able to see the true proportions of the various parts. I 

 will merely take this opportunity of offering to our visitors, in 

 the name of this Section and of English geologists in general, a 

 hearty welcome to our shores, feeling that not only will our 

 science be benefited enormously by the simplification of geological 

 nomenclature, but that we ourselves shall derive great advantage 

 by a closer personal contact than we have enjoyed hitherto. 



Our science has made great strides during the last twenty-four 

 years, and she has profited much from the development of her 

 sisters. The microscopic analysis of the rocks has opened out a 

 new field of research, in which physics and chemistry are in 

 friendly rivalry, and in which fascinating discoveries are being 

 made almost day by day as to metamorphism, and the crushing 

 and shearing forces brought to bear upon the cooling and con- 

 tracting crust while the earth was young. The deep-sea explora- 

 tions have revealed the structure and the deposits of the ocean 

 abysses ; and the depths supposed to be without life, like the 

 fabled deserts in the interior of Africa, are now known to teem 

 with varied forms glowing with the richest colours. From a 

 comparison of these deposits with the stratified rocks we mav 

 conclude that the latter are marginal, and deposited in depths 

 not greater than 1000 fathoms, or the shore end of the Globi- 

 gerina ooze, and most of them at a very much less depth, and 

 that consequently there is no proof in the geological record of the 

 ocean depths having ever been in any other than their present 

 places. 



In North America the geological survey of the Western States 

 has brought to light an almost unbroken series of animal remains, 

 ranging from the Eocene down to the Pleistocene age. In these 

 we find the missing links in the pedigree of the horse, and 

 sufficient evidence of transitional forms to cause Prof. Flower to 

 restore to its place in classification the order Ungulata of Cuvier. 

 These may be expected to occupy the energies of our kinsmen on 

 the other side of the Atlantic for many years, and to yield further 

 proof of the truth of the doctrine of evolution. The use of 

 this word reminds me how much we have grown since 1864, 

 when evolution was under discussion, and when biological, 

 physical, and geological laboratories could scarcely be said to 

 have existed in this country. Truly may the scientific youth of 

 to-day make the boast — 



" We are much better off than our fathers were ; " while we, the 

 fathers, have the poor consolation of knowing that when they 

 are fathers their children will say the same of them. There is 

 reason to suppose that our science will advance more swiftly in 

 the future than it has in the past, because it has more delicate and 

 precise methods of research than it ever had before, and because 

 its votaries are more numerous than they ever were. 



In 1864 the attention of geologists was mainly given to the 

 investigations of the later stages of the Tertiary period. The 

 bent of my pursuits inclines me to revert to this portion of 

 geological inquiry, and to discuss certain points which have 

 arisen during the last few years in connection with the classifi- 

 catory value of fossils, and the mode in which they may be best 

 used for the co-ordination of strata in various parts of the world. 



The principle of homotaxy, first clearly defined by Prof. 

 Huxley, has been fully accepted as a guiding principle in place 

 of synchronism or contemporaneity, and the fact of certain 

 groups of plants and animals succeeding one another in a definite 



order, in countries remote from each other, is no longer taken to 

 imply that each was living in the various regions at the same 

 time, but rather, unless there be evidence to the contrary, that 

 they were not. While, however, there is a universal agreement 

 on this point among geologists, the classifieatory value of the 

 various divisions of the vegetable and animal kingdoms is still 

 under discussion, and, as has been very well put by my pre- 

 decessor in this chair at Montreal, sometimes the evidence of one 

 class of organic remains points in one direction, while the 

 evidence of another class points in another and wholly different 

 direction, as to the geological horizon of the same rocks. The 

 flora, put into the witness-box by the botanist, says one thing, 

 while the Mollusca or the Vertebrata say another thing in the 

 hands of their respective counsel. There seems to be a tacit 

 assumption that the various divisions of the organic world present 

 the same amount of variation in the rocks, and that consequently 

 the evidence of every part of it is of equal value. 



It will not be unprofitable to devote a few minutes to this 

 question, premising that each case must be decided on its own 

 merits, without prejudice, and that the whole of the evidance of 

 the flora and fauna must be considered. We will take the flora 

 first. 



The Cryptogamic flora of the later Primary rocks shows but 

 slight evidence of change. The forests of Britain and of Europe 

 generally, and of North America, were composed practically of 

 the same elements — Sigillaria, Calamites, and conifers allied to 

 the Ginkho — throughout the whole of the Carboniferous (16,336 

 feet in thickness in Lancashire and Yorkshire) and Devonian 

 rocks, and do not present greater differences than those which 

 are to be seen in the existing forests of France and Germany. 

 They evidently were continuous both in space and lime, from 

 their beginning in the Upper Silurian to their decay and ultimate 

 disappearance in the Permian age. This disappearance was 

 probably due to geographical and climatic changes, following the 

 altered relations of land to sea at the close of the Carboniferous 

 age, by which Secondary plants, such as Voltzla and Walchia, 

 were able to find their way by migration from an area hitherto 

 isolated. The Devonian formation is mapped off from the 

 Carboniferous, and this from the Permian, but to a slight degree 

 by the flora, and nearly altogether by the fauna. While the 

 fauna exhibits great and important changes, the flora remained 

 on the whole the same. 



The forests of the Secondary period, consisting of various 

 conifers and cycads, also present slight differences as they are 

 traced upwards through the Triassic and Jurassic rocks, while 

 remarkable and striking changes took place in the fauna, which 

 mark the division of the formations into smaller groups. As the 

 evidence stands at present, the cycads of the Lias do not differ in 

 any important character from those of the Oolites or the Wealden, 

 and the Salisburia in Yorkshire in the Liassic age is very similar 

 to that of the Island of Mull in the Early Tertiary, and to that 

 (Salisburia adiantifolia) now living in the open air in Kew 

 Gardens. 



Nor do we find evidence of greater variation in the Dicotyle- 

 donous forests, from their first appearance in the Cenomanian 

 stage of the Cretaceous rocks of Europe and America, through 

 the whole of the Tertiary period down to the present time. In 

 North America, the flora of the Dakota series so closely re- 

 sembles the Miocene of Switzerland, that Dr. Heer had no hesi- 

 tation in assigning it in the first instance to the Miocene age. 

 It consists of more than a hundred species, of which about one- 

 half are closely allied to those now living in the forests of North 

 America — sassafras, tulip, plane, willow, oak, poplar, maple, 

 beech, together with Sequoia, the ancestor of the giant redwood 

 of California. The first palms also appear in both continents at 

 this place in the geological record. 



In the Tertiary period there is an unbroken sequence in the 

 floras, as Mr. Starkie Gardner has proved, when they are traced 

 over many latitudes, and most of the types still survive at the 

 present day, but slightly altered. If, however, Tertiary floras 

 of different ages are met with in one area, considerable differ- 

 ences are to be seen, due to progressive alterations in the climate 

 and altered distribution of the land. As the temperature of the 

 northern hemisphere became lowered, the tropical forests were 

 pushed nearer and nearer to the equator, and were replaced by 

 plants of colder habit from the northern regions, until ultimately, 

 in the Pleistocene age, the Arctic plants were pushed far to 

 the south of their present habitat. In consequence of this, Mr. 

 Gardner concludes that "it is useless to seek in the Arctic 

 regions for Eocene floras as we know them in our latitudes, for 



