But Von Buch was indefatigable. For years he lived the life of an itinerant geologist. With a shirt and a pair of stockings in his pocket and a geological hammer in his hand he travelled all over Europe on foot. The results of his foot-journey to Scandinavia were among his most important contributions to geology. He went also to the Canary Islands; and it is in his extensive work on the geological formations of these islands that he showed conclusively not only the Plutonic character of all unstratified rocks, but also that to their action upon the stratified deposits the inequalities of the earth's surface are chiefly due. He first demonstrated that the melted masses within the earth had upheaved the materials deposited in layers upon its surface, and had thus formed the mountains. No geologist has ever collected a larger amount of facts than Von Buch, and to him we owe a great reform not only in geological principles, but in methods of study also. An amusing anecdote is told of him, as illustrating his untiring devotion to his scientific pursuits. In studying the rocks, he had become engaged also in the investigation of the fossils contained in them. He was at one time especially interested in the _Terebratulæ_ (fossil shells), and one evening in Berlin, where he was engaged in the study of these remains, he came across a notice in a Swedish work of a particular species of that family which he could not readily identify without seeing the original specimens. The next morning Von Buch was missing, and as he had invited guests to dine with him, some anxiety was felt on account of his non-appearance. On inquiry, it was found that he was already far on his way to Sweden: he had started by daylight on a pilgrimage after the new, or rather the old, _Terebratula_. I tell the story as I heard it from one of the disappointed guests. All great natural phenomena impressed him deeply. On one occasion it was my good fortune to make one of a party from the "Helvetic Association for the Advancement of Science" on an excursion to the eastern extremity of the Lake of Geneva. I well remember the expressive gesture of Von Buch, as he faced the deep gorge through which the Rhone issues from the interior of the Alps. While others were chatting and laughing about him, he stood for a moment absorbed in silent contemplation of the grandeur of the scene, then lifted his hat and bowed reverently before the mountains. Next to Von Buch, no man has done more for modern geology than Elie de Beaumont, the great French geologist. Perhaps the most important of his generalizations is that by which he has given us the clue to the limitation of the different epochs in past times by connecting them with the great revolutions in the world's history. He has shown us that the great changes in the aspect of the globe, as well as in its successive sets of animals, coincide with the mountain-upheavals.