24 REPORT— 1892. 



and Playfair. With the peneti'ation of genius these illustrious teachers 

 perceived that if the broad masses of land and the great chains of moun- 

 tains owe their origin to stupendous movements which from time to time 

 have convulsed the earth, their details of contour must be mainly due to 

 the eroding power of running water. They recognised that as the surface 

 of the land is continually worn down, it is essentially by a process of 

 sculpture that the physiognomy of every country has been developed, 

 valleys being hollowed out and hills left standing, and that these in- 

 equalities in topographical detail are only varying and local accidents in 

 the progress of the one great process of the degradation of the land. 



From the broad and guiding outlines of theory thus sketched we have 

 now advanced amid ever- widening multiplicity of detail into a fuller and 

 nobler conception of the origin of scenery. The law of evolution is 

 written as legibly on the landscapes of the earth as on any other page of 

 the Book of Nature. Not only do we recognise that the existing topo- 

 graphy of the continents, instead of being primeval in origin, has gradu- 

 ally been developed after many precedent mutations, but we are enabled 

 to trace these earlier revolutions in the structure of every hill and glen. 

 Each mountain-chain is thus found to be a memorial of many successive 

 stages in geographical evolution. Within certain limits, land and sea 

 have changed places again and again. Volcanoes have broken out and 

 have become extinct in many countries long before the advent of man. 

 Whole tribes of plants and animals have meanwhile come and gone, and 

 in leaving their remains behind them as monuments at once of the slow 

 development of organic types, and of the prolonged vicissitudes of the 

 terrestrial surface, have furnished materials for a chronological arrange- 

 ment of the earth's topographical features. Nor is it only from the 

 organisms of former epochs that broad genei'alisations may be drawn 

 regarding revolutions in geography. The living plants and animals of 

 to-day have been discovered to be eloquent of ancient geographical 

 features that have long since vanished. In their distribution they tell 

 us that climates have changed, that islands have been disjoined from 

 continents, that oceans once united have been divided from each other, 

 or once separate have now been joined ; that some tracts of land have 

 disappeared, while others for prolonged periods of time have remained in 

 isolation. The present and the past are thus linked together not merely 

 by dead matter, but by the world of living things, into one vast system 

 of continuous progression. 



In this marvellous increase of knowledge regarding the transforma- 

 tions of the earth's surface, one of the most impressive features, to my 



