January 5, 1893] 



NATURE 



2 19 



Idaho, where a country as large as France and Great 

 Britain combined has been flooded with a continuous 

 sheet of basalt. But stratigraphical studies were only 

 part of the necessary initiation. Sir Archibald had been 

 one of the first field-geologists in England to perceive 

 the importance of microscopic investigation as an 

 adjunct to field work. He might well have left the care 

 of that special study to some officer in the Survey; but 

 he wished to make himself master of the subject. Con- 

 nected by personal friendship with Zirkel, Renard, and 

 other eminent petrographers, he gave to that branch of 

 the Survey such a vigorous impulse, that upwards of 

 5000 slices of British rocks were soon prepared and 

 classed in the collections of the museum in Jermyn 

 Street ; and if he can now rely with full confidence on 

 his distinguished professional officer, Mr. Harris Teall, j 

 for any determination of rocks, he himself has won all 

 necessary competence in that department of science, which 

 has been so much enlarged during the last twenty years. 



An undertaking so ably provided for could not but 

 prove successful. It is not, of course, our purpose to give 

 an account of the results arrived at. The " History of 

 \'olcanic Action in the Area of the British Isles," as it was 

 presented in the presidential addresses for the years 1891 

 and 1892, is so much condensed that it must be read 

 /// extenso by every one who takes interest in the matter. 

 We would only call attention to the final summary, where 

 some important and far-reaching conclusions are deduced 

 froin the observed facts. One of them is that British 

 volcanoes have been active in sinking rather than in 

 rising areas ; to which it is added that the earlier 

 eruptions of each period were generally more basic, while 

 the later intrusions were more acid. 



When presenting " a connected narrative of ascertained 

 knowledge regarding the successive epochs of volcanic 

 energy in this country," Sir Archibald did more than write 

 an important chapter of British geology. It maybe said 

 that he definitively settled the long-controverted question, 

 whether there has been any essential difference or not 

 between the display of volcanic activity at various 

 !,reological periods. Not very long ago some scientific 

 schools — above all, on the Continent — showed the greatest 

 reluctance to admit that true volcanoes could have existed 

 during the Palaeozoic era. When they were told of 

 Cambrian lavas and feispathic ashes, of Silurian tuffs, 

 especially of Precambrian felsites, they could not restrain 

 a strong feeling of incredulity. Against old granitic or 

 porphyritic eruptions they had nothing to object ; but the 

 volcanic fades appeared to them a privilege restricted to 

 recent geological times. To this the present writer might 

 bear personal testimony, as he found his " way of Damas " 

 only when he was fortunate enough to ramble over North 

 Wales, and gather with his own hands pieces of vesicular 

 lava embedded in the tuffs of the Snowdon, or boulders 

 of true felsite lying at the base of the Cambrian series at 

 Llanberis. 



Not only has Sir Archibald, in common with his 

 countrymen, always escaped that kind of misconception^ 

 but he will have contributed more effectively than any 

 other to place the matter in the true light. Thanks to 

 the cliffs of Scotland, he has been able to trace the roots of 

 old volcanoes, to show true volcanic bombs entombed in 

 NO. 1210. VOL. 47] 



sediments, and to mark the site round which vast piles of 

 lavas and tuffs, 5000 or 6000 feet in thickness, had been 

 heaped up. Likewise, in his previous paper on Tertiary 

 volcanoes, he had established by indisputable sketches 

 that the granitic rocks of the islands of Mull and Skye 

 were ejected during the earlier part of the Tertiary 

 period, and that they belong to the central mass of in- 

 trusions, the lateral veins of which have taken the form 

 of granophyres. 



There is another kind of useful geological work which 

 Sir Archibald has a right to be credited with ; we allude 

 to the restoration of the most friendly relations between 

 the official Survey and the Geological Society of 

 London. For many years those relations had been 

 maintained at a rather low temperature ; both independ- 

 ent geologists and Government's surveyors showed, as it 

 were, more inclination to mutual and severe criticism 

 than to brotherly co-operation. This period of mis- 

 understanding is now well over. Thanks to the present 

 Director, the Geological Society has more than once 

 received the early flower of the capital results obtained 

 by the Survey, and the recent Presidentship of Sir Archie 

 bald has solemnly sanctioned the return of a harmony 

 which will prove of great benefit to the advancement of 

 geological science in England. 



This is a very brief and imperfect account of the chief 

 work accomplished by the field-geologist, a work which 

 would have been sufficient for the whole of a man's life. 

 But we have now to consider in Sir Archibald the master 

 who has been engaged in important educational duties. 

 When he was appointed in 1871 to the chair of Geology 

 at Edinburgh he had the whole work of that department 

 to organize, a task which may be wearisome, but which 

 involves great benefit for a man of labour, as he must 

 face every difficulty, and obtain day by day a clear and 

 personal idea of all that is required for teaching. To that 

 we are indebted for the undisputed superiority which Sir 

 Archibald has displayed in his " Text-book," as well as 

 in his other educational writings, such as the " Class- 

 Book," a very model of clearness, whereby it has been once 

 more demonstrated that those only are qualified for writing 

 elementary books, who are in the fullest possession of the 

 whole matter. Likewise he is the author of small books or 

 "primers" on physical geology and geography, of which 

 some hundreds of thousands of copies have been sold, and 

 which have been translated into most European languages 

 as well as into some Asiatic tongues. This exceptional 

 success will be easily understood if we remember that in 

 Sir Archibald's works the traditional barrenness of geology 

 is always smoothed and adorned by a deep and intense 

 feeling for nature. Nobody has done more than he to 

 associate geological science with the appreciation of 

 scenery. In numberless writings he has undertaken to 

 explain the origin of existing topographical features. 

 Among others reference may be made to the volume on 

 " The Scenery of Scotland viewed in connection with its 

 Physical Geology," first published in 1869, of which a new 

 edition appeared in 1887; also to "Geographical Evo- 

 lution," in the Proceedings of the Royal Geographical 

 Society for 1879; and "On the Origin of the Scenery 

 of the British Isles," published in Naturk (vol. xxix. 

 pp. 347. 396, 419. 442). 



