THE LEWIS BROOKS MUSEUM. 37 



the amount and accuracy of the work done by him is mar- 

 vellous. I have have had occasion to go over many parts of 

 the ground formerly investigated by hiui, and I have con- 

 stantly had reason to admire the accuracy of his work. 

 Some of his conclusions, where he was not able to fully 

 work out the geology, viewed in the light of late cliscove- 

 ries / seem to be veritable intuitions, so amply have they 

 been justified. 



It remains now to examine briefly the nature of the 

 problems with which Geology deals. It will be best for this 

 purpose to select for illustration some one of the many that 

 present themselves, and see what Geology teaches concern- 

 ing it. The history of the plant life of the globe is well 

 suited to show the geological method of dealing with the 

 many questions that engage the attention of the Paleontolo- 

 gist. 



The surface features of the earth, immediately after the 

 formation of & solid crust, were, no doubt, far simpler than 

 they are at present. No high lands or mountains existed. 

 Water covered nearly the whole surface. There were no 

 zones of climate, and the first forms of vegetation were con- 

 sequently of the simplest kind, and nearly the same plants 

 were found everywhere, even near the poles. These vege- 

 table forms were not land, but marine plants, or sea weeds. 



As contraction of the crust of the earth took place, 

 from the continued loss of heat, elevations and depressions 

 of the land occurred. The seas deepened and narrowed, 

 and the lands grew higher and more extensive. The action 

 of the atmosphere and of moving waters wore down some 

 portions and built up others, covered the surface of the 

 earth with layer after layer of sedimentary rocks, and thus 

 increased the complexity of the earth. By this means an 

 ever increasing variety of fcrces was brought to bear on the 

 plant life. Owing to these causes great changes took place 

 in the vegetation covering the surface of the earth. Entire 

 classes of plants became extinct, and were succeeded by 



