242 Scrope— Origin of Hills and Valleys. 



of the earth like so many Jacks in the box." And I have assisted, 

 I hope, by adducing arguments and facts in contravention of the 

 theory of "elevation craters," of Von Btich, Humboldt, and Elie de 

 Beaumont, effectively to put down this catastrophal doctrine. But as 

 even Mr. Jukes himself states (loc. cit.) that " all lands have eisen 

 out of the ocean," and it is clear that the ocean bed itself is but a 

 series of great valleys, he must admit that some superficial portions 

 have been upheaved far above others, and consequently that moun- 

 tainous or high districts are to a considerable extent the result of 

 elevatory internal movements, the intervening hollows, of depressing 

 ones. What, I may ask, has carried Tertiary marine strata up to 

 heights several thousand feet above the sea in the Alps, Pyrenees, 

 and Himalayas, nay, I would add, in the Andes, Etna, and Ischia, — 

 for elevation in mass is by undeniable evidence, in these and many 

 other cases, proved to have affected volcanic cones, no less than me- 

 tamorphic or palaeozoic mountains ? What but the action of internal 

 force ? And ought it to be declared ex cathedra by a professor of the 

 Science, that " the action of internal force has had no direct influence 

 on the external features of the ground ?" The process has, no doubt, 

 been gradual. The Alps did not jump up like a " Jack in the box." 

 But yet they have risen by many thousand feet from below the sea- 

 level, while the valley -beds of the Adriatic and the Mediterranean 

 either remained stationary or subsided to a lower level. Is it not 

 indeed generally true that the course of mountain ranges and of the 

 intervening valleys has for the most part been determined by the 

 lines of axial upthrust of subterranean matter, the consequent strike 

 of the elevated strata on either side, and anticlinal or synclinal lay 

 of their folds — all the results of internal force ? Is not the basin of 

 Switzerland a synclinal valley between the elevated ridges of the Alps 

 and Jura ? Is not that of the Po and the Adriatic the same between 

 the upheaved Alps on the one hand and the Apennines on the other ? 



So far, then, from agreeing with what seems to be the opinion of 

 Professor Jukes, I would maintain that all the grander features of 

 the earth's surface have been fashioned by internal rather than by 

 external forces — the influence of the latter being confined to what 

 may be called the minor details, the planing and chiselling, rather 

 than the moulding, of the subject matter. And in respect even to 

 some of the minor details, such as the transverse valleys, that act as 

 tributaries to these grander depressions of the surface, there seems 

 good ground for believing many of them to owe their origin, and 

 consequently the course of the superficial waters or ice-streams that 

 have, since their emergence from the sea, widened and deepened 

 them by erosion, to the transverse cracks and fissures which could 

 not fail to accompany the violent elevation of more or less solid 

 strata, even though effected by gradual throes. 



It is well known how liable the followers of any science are to 

 push, for a time, some favored theory to an extreme extent — to the 

 complete neglect of other equally influential causes. It may, there- 

 fore, not be inopportune for me at the present moment to recal the 

 votaries of mechanical geology from the exclusive consideration of 



