President of the Geological Society for 1850. 17 



wholly inappreciable to the naturalist, still it is certainly far 

 less manifest than the revolution always in progress in the 

 inorganic world. Every year some volcanic eruptions take 

 place, and a rude estimate might be made of the number of 

 cubic feet of lava and scorise poured or cast out of various 

 craters. The amount of mud and sand deposited in deltas, 

 and the advance of new land upon the sea, or the annual re- 

 treat of wasting sea-cliffs, are changes the minimum amount 

 of which might be roughly estimated. The quantity of land 

 raised above or depressed below the level of the sea might 

 also be computed, and the change arising from such move- 

 ments in a century might be conjectured. Suppose the 

 average rise of the land in some parts of Scandinavia be five 

 feet in a hundred years, the present sea-coast might be up- 

 lifted 700 feet in fourteen thousand years ; but we should 

 have no reason to anticipate, from any zoological data hither- 

 to acquired, that the molluscous fauna of the northern seas 

 would in that lapse of years undergo any sensible amount of 

 variation. If a botanist were asked how many earthquakes 

 and volcanic eruptions might be expected, and how much the 

 relative level of land and sea might be altered, or how far 

 the principal deltas will encroach upon the ocean, or sea- 

 cliffs recede from the present shores, before the species of 

 European forest-trees die out, he would reply that such alter- 

 ations in the inanimate world might be multiplied indefinitely 

 before he should have reason to anticipate, by reference to 

 any known data, that the existing species of trees in our 

 forests would disappear and give place to others. In a word, 

 the movement of the inorganic world is obvious and palpable, 

 and might be likened to the minute-hand of a clock, the pro- 

 gress of which can be seen and heard, whereas the fluctua- 

 tions of the living creation are nearly invisible, and resemble 

 the motion of the hour-hand of a time-piece. It is only by 

 watching it attentively for some time, and comparing its 

 relative position after an interval, that we can prove the 

 reality of its motion. If therefore in the coal-measures of 

 South Wales or Nova Scotia we find the same fossil trees 

 repeated through a mass of strata formed in shallow water 

 10,000 feet thick, we ought not to feel surprised, but merely 

 VOL. L. NO. XCIX. — JANUARY 1851. B 



