298 Prof. A. C. Ramsay on the Erosion 



tures M is anything but evident ; and I for one believe that the 

 " ruptures" are only manifest to those who accept such hypotheses 

 " without inquiring into what has been the former state of things, 

 or what will be the future"*. To this day there is no error so 

 common, even among geologists, as that which vaguely attri- 

 butes the form and nature of the present surface-outlines of the 

 earth chiefly to the operation of violent disturbance in recent 

 geological times, not clearly perceiving that the great and small 

 outlines of mountain- chains, of valleys, of river-gorges and of 

 plains are the combined results of an immense number of opera- 

 tions, many of these going back to exceedingly remote periods of 

 geological antiquity, and a great proportion of their details being 

 lost even to probable conjecture. 



These operations, however, in the production of scenery mainly 

 resolve themselves into the following series, the parts of which, 

 ever since land and water first existed, may be arranged in any 

 possible combination. 



a. Oscillation with respect to the sea-level of rocks that have or 

 have not been contorted and metamorphosed, accompanied by pauses 

 in oscillation of greater or less duration. 



b. Great plains of marine denudation. 



c. Subaerial denudations of all kinds ; wearing away of sea- 

 coasts ; and in the interior of the country, chemical decompositions, 

 frost, snow, ice, wind, rain, and rivers ; modified by height of land, 

 and the various positions, hardness, and other characters of rocks. 



Contortion and metamorphism seem to be essential accompa- 

 niments of all great mountain-chains. It may also possibly 

 be proved that in intensely contorted regions mountain-chains 

 are high or low according to the relative antiquity of disturb- 

 ance, while sometimes the irregular protuberances, as in the 

 Devonian and other rocks of the Rhine and Moselle, have been 

 planed away altogether. 



Plains of marine denudation are sure to be inclined at a very 

 low angle if formed during slow depression of the land. 



Further, while the sea helps to make bays, the other agents of 

 waste enumerated above cut out all mountain-peaks not volcanic, 

 all the minor valleys, in this term including such valleys as those 

 of the Alps, the Highlands, Wales, &c, but not such a valley as 

 the great one that lies between the Alps and the Jura. 



Fractures and volcanos, in the production of the great scenic 

 features of continental physical geography, are, as a rule, mere 

 subordinate and subsidiary accidents, the first modifying the 

 effects of denudation by juxtaposition of different kinds of rocks, 

 and the second (which seem to be connected with general ele- 

 vations) forming accidental mountains, hills, and hilly regions, 

 * Hutton, vol. ii. p. 257. 



