NA TURE 



[February 25, 1892 



VOLCANIC ACTION IN THE BRITISH ISLES. 



A T the anniversary of the Geological Society, held on 

 ■^"^ the 19th inst, the retiring President, Sir Archibald 

 Geikie, gave the annual address, which w^as devoted to a 

 continuation of the subject treated of by him last year. 

 He now dealt with the history of volcanic action in this 

 country from the close of the Silurian period up to older 

 Tertiary time. The remarkable volcanic outbursts that 

 took place in the great lakes of the Lower Old Red Sand- 

 stone were first described. From different vents over 

 central Scotland, piles of lava and tuff, much thicker than 

 the height of Vesuvius, were accumulated, and their re- 

 mains now form the most conspicuous hill-ranges of that 

 district. It was shown how the subterranean activity 

 gradually lessened and died out, with only a slight revival 

 in the far north during the time of the Upper Old Red 

 Sandstone, and how it broke out again with great vigour 

 at the beginning of the Carboniferous period. Sir Archi- 

 bald pointed out that the Carboniferous volcanoes belonged 

 to two distinct types and two separate epochs of eruption. 

 The earlier series produced extensive submarine lava- 

 sheets, the remains of which now rise as broad terraced 

 plateaux over parts of the lowlands of Scotland. The 

 later series manifested itself chiefly in the formation of 

 numerous cones of ashes, like the puys of Auvergne, 

 which were dotted over the lagoons and shallow seas in 

 central Scotland, Derbyshire, Devonshire, and the south- 

 west of Ireland. After a long quiescence, volcanic action 

 once more reappeared in the Permian period ; and 

 numerous small vents were opened in Fife and Ayrshire, 

 and far to the south in Devonshire. With these eruptions 

 the long record of Palccozoic volcanic activity closed. No 

 trace has yet been discovered of any volcanic rocks inter- 

 calated among the Secondary formations of this country, 

 so that the whole of the vast interval of the Mesozoic 

 period was a prolonged time of quiescence. At last, 

 when the soft clays and sands of the Lower Tertiary 

 deposits of the south-east of England began to be laid 

 down, a stupendous series of fissures was opened across 

 the greater part of Scotland, the north of England, and 

 the north of Ireland. Into these fissures lava rose, form- 

 ing a notable system of parallel dykes. Along the great 

 hollow from Antrim northwards between the outer 

 Hebrides and the mainland of Scotland, the lava flowed 

 out at the surface and formed the well-known basaltic 

 plateaux of that region. 



The address concluded with a summary of the more 

 important facts in British volcanic history bearing on the 

 investigation of the nature of volcanic action. Among 

 these Sir Archibald laid special stress on the evidence 

 for volcanic periods, during each of which there was a 

 gradual change of the internal magma from a basic to an 

 acid condition, and he pointed out how this cycle had 

 been repeated again and again even within the same 

 limited area of eruption. In conclusion, he dwelt on the 

 segregation of minerals in large eruptive masses, and in- 

 dicated the importance of this fact in the investigation, 

 not only of the constitution and changes of the volcanic 

 magma, but also of the ancient gneisses where what 

 appear to be original structures have not yet been 

 effaced. 



THE CENTENARY OF MURCHISON. 



C\^ February 19, 1792, Roderick Impey Murchison 

 ^-^ was born at Tarradale, in Ross-shire. By a 

 curious and appropriate coincidence, the anniversary 

 of the Geological Society, the date of which is fixed by 

 statute, fell this year on the 19th of the present month, 

 the hundredth anniversary of the birth of the illustrious 

 author of the " Silurian System." It was a further re- 

 markable conjuncture that the President of the Society, 



NO. 1165, VOL. 45] 



who had to give the annual address, and take notice of 

 the centenary, was Murchison's literary executor, who 

 was designated by him as the first Professor of Geology 

 in the chair which he founded in the University of 

 Edinburgh, and who now fills the office which he held 

 for so many years — that of Director-General of the Geo- 

 logical Survey. In referring to the doubly interesting 

 features of this anniversary, Sir Archibald Geikie spoke 

 of his great chief with warm admiration. The twenty 

 years which have passed since Murchison's death enable 

 geologists to make a truer estimate of Murchison's real 

 achievements than was possible at the time when his 

 commanding presence filled so prominent a place in the 

 scientific world of his day. They have been able to 

 correct some of his observations and discard some of his 

 generalizations, yet the solid mass of original work done 

 by him remains as a lasting memorial of his genius and 

 industry. In the broad basis of facts, and in the skilful 

 marshalling of these facts in their ordered relations, which 

 distinguished his work among the Silurian rocks, the 

 hand of a consummate master of geological investigation 

 is to be traced. His name has become a household word 

 in geology, and will go down to future ages as that of one 

 of the great pioneers of the science. 



Murchison, during all his scientific career, was closely 

 associated with the Geological Society, and took a keen 

 personal interest in its welfare. By his will he left a 

 sum of money to found a medal and fund to be given 

 annually for the reward and encouragement of geological 

 research. This year the medal was awarded to Prof A. 

 H. Green, of Oxford, and the balance of the fund to 

 Mr. Beeby Thomson. An interesting proof of the affec- 

 tionate regard entertained for Murchison's memory was 

 afforded by an announcement made by the President. 

 He stated that, a it.w days before the meeting, an old 

 friend of Murchison, who desired to remain unknown, 

 had come to him and asked to be allowed to offer a slight 

 tribute in remembrance of the man and his work, on his 

 centenary, at the anniversary meeting of the Society. 

 The President was requested to select two geologists (by 

 preference Scotsmen) who were carrying on geological 

 work in Murchison's spirit, and seeking to advance the 

 special branches of research to which he devoted himself, 

 and to present to each of them a cheque for ^^50, 

 with a framed portrait of the author of the " Silurian 

 System." Sir Archibald Geikie said that the task as- 

 signed to him was made comparatively easy by the terms 

 of the generous gift. He had no doubt that the Society 

 would agree with him that there were pre-eminently two 

 Scottish geologists marked out as recipients of this bene- 

 faction, who were disciples of Murchison, and were 

 carrying on his work, but with no slavish obedience to 

 the opinions of their master, and who, by their conjoint 

 work, alike with hammer and pen, well deserved this un- 

 expected and appropriate reward — Mr. B. N. Peach and 

 Mr. John Home. As a touching addition to this pleasing 

 incident, we have since learnt that while the anniversary 

 was being held at Burlington House, the faithful friend 

 who had made this offering to Murchison's memory 

 was engaged in the cemetery at Brompton carefully 

 brushing and washing his tomb. Driving snow was 

 falling at the time from a gloomy sky, in strange contrast 

 with the glow of affection that was piously renovating 

 the inscription that records the name and resting-place 

 of one of the great leaders of modern geology. 



H. W. BATES, THE NATURALIST OF THE 

 AMAZONS. 



HENRY WALTER BATES was a native of Leicester, 

 and was engaged in his father's warehouse when, 

 about the year 1845, he made the acquaintance of Alfred 

 Russel Wallace, then English master in the Collegiate 



