258 THE POPULAR SCIENCE MONTHLY. 



which suggested Murchison's view. The displacements were ac- 

 companied by modifications of the rocks, of which Geikie wrote 

 that " in exchange for this (Murchison's) abandoned belief we are 

 presented with startling new evidence of original metamorphism 

 on a colossal scale, and are admitted some way into the secret of 

 the processes whereby it has been produced." 



Sir Archibald Geikie's chief geological work, according to the 

 estimate of Nature, seems to be his exhaustive review of the vol- 

 canic history of the British Isles. The northwestern part of Great 

 Britain is marked, like the Snake River region in our own coun- 

 try, by the evidences of the outpouring over the land of immense 

 sheets of lava, which in the present instance took place in Tertiary 

 times. Sir Archibald made it his task in the investigation of this 

 phenomenon " to discern the site of the centers of eruption, and 

 determine the old chimneys, the remnants of which give a glimpse 

 into the lowest parts of ascending lavas ; to discriminate the vol- 

 canic necks, the intrusive sheets and dikes, the bedded lavas and 

 the tuffs." Evidences of still earlier volcanic activity were also 

 found in the Old Red Sandstone of Scotland, and in the oldest 

 formations of England and Wales. In order to prepare himself 

 more thoroughly for the investigation of this phenomenon, Mr. 

 Geikie traveled over much of Europe, from northern Norway to 

 the Lipari Islands; then came over to Canada and the United 

 States, and followed the course of our geological surveys, particu- 

 larly in the Western States and Territories and the lava-covered 

 regions. In another department of the same investigation he gave 

 more attention to petrological studies than any Englishman had 

 done before him. Besides giving rise to many valuable memoirs 

 relating directly to what he had seen and observed, these studies 

 contributed greatly to the enlargement of Prof. Geikie's views 

 and to the increase of the breadth of his work ; and some of their 

 results may be seen in the greater richness of illustration appar- 

 ent in his subsequent writings. Their mature fruit is presented 

 as a whole in his presidential addresses of 1891 and 1892. He was 

 especially interested, they being exactly in the line of his princi- 

 pal study, in the lava*beds of Snake River ; and in his essay on 

 the Lava Fields of Northwestern Europe refers to them as the site 

 which first enabled him to realize the conditions of volcanic action 

 described by Richtofen the emission of vast floods of lava with- 

 out formation of cones and craters and, without acquiescing in 

 all that author's theoretical conclusions, to judge of the reality of 

 the distinction " which he rightly drew " between massive erup- 

 tions and ordinary volcanoes with cones and craters. 



We have referred to Prof. Geikie's work in tracing the origin 

 of the present shaping of land surfaces and of natural scenery to 

 its geological factors as constituting one of his special titles to 



