p:volutional geology/ 



By Prof. ^^^ J. SoLLAS, F. R. s. 



EVOLUTIONAL (4EOLOGY. 



The close of one century, the dawn of another, may naturally sug- 

 gest .some brief retrospective glance over the path along which our 

 science has advanced, and some general survey of its present position 

 from which we may gather hope of its future progress; but other con- 

 nection with geology the beginnings and endings of centuries have 

 none. The great periods of movement have hitherto begun, as it Avere, 

 in the early twilight hours, long before the dawn. Thus the first step 

 forward, since which there has been no retreat, was taken by Steno in 

 the year 1661>; more than a centmy elapsed before James Hutton 

 (1785) gave fresh energj^ and better direction to the faltering steps of 

 the young science; while it was less than a century later (1863) when 

 Lord Kelvin brought to its aid the powers of the higher mathematics 

 and instructed it in the teachings of modern physics. From Steno 

 onward the spirit of geology was catastrophic; from Hutton onward 

 it grew increasingly uniformitarian; from the time of Darwin and 

 Kelvin it has l)ecome evolutional. The amljiguity of the word "uni- 

 formitarian'' has led to a good deal of fruitless logomachy, against 

 which it may be as well at once to guard l)y indicating the sense in 

 which it is used here. In one way we are all unif ormitarians, i. e. , 

 we accept the doctrine of the ''uniform action of natural causes," but, 

 as applied to geology, uniformity means more than this. Defined in 

 the briefest fashion it is the geology of Lyell. Hutton had given us a 

 ''Theory of the Earth," in its main outlines still faithful and true, and 

 this Lyell spent his life in illustrating and advocating, but as so com- 

 monly happens the zeal of the disciple outran the wisdom of the master, 

 and mere opinions were insisted on as necessarj^ dogma. What did it 

 matter if Hutton, as a result of his inquiries into terrestrial history, had 



'Opening address by Prof. W. J. Sollas, D. Sc, LL. D., F. R. S., president of tlie 

 Section f)f Geology of the British Association for the Advancement of Science, 1900. 

 Reprinted from Nature No. 1611, vol. 62, September 13, 1900. 



