THE EARTH'S SHAPE 



things. If he did not know the peculiarities of fresh- 

 water shells, how would he be able to say the shells in 

 the marl deposit were fresh-water animals (and that 

 therefore a lake once lay there) and not sea shells. If the 

 labour of the geologist were concerned merely with the 

 former changes of the earth^s surface how sea and land 

 have changed places, how rivers have altered their 

 courses, how valleys have been dug out, and how moun- 

 tains have been carved, how plains have been spread out, 

 and how all these things have been written on the frame- 

 work of the earth he would still feel one very great 

 want, the want of living interest. But that also his 

 science gives him, for in these past eras living things 

 dwelt and moved and had their being. And it is one of 

 the most entrancing pursuits of the geologist to trace 

 their lives, their descent and ascent, and the relics of 

 themselves that they left. 



