CH. XL. SIX CHARLES L YELL. 443 



adly. The amount of mud carried by mighty streams, 

 such as the Ganges, the Nile, and the Mississippi, and laid 

 down in the sea at their mouths. 



3dly. The amount of lime, iron, and other minerals 

 brought up by springs from the inside of the earth, and thrown 

 down on the surface. 



4thly. The tides and currents of the sea, and how they 

 wash up fiesh land on some coasts and eat away the land 

 on others. 



5thly. The growth of corals in the sea, and how remains 

 of their skeletons become cemented into limestone. 



6thly. The volcanoes which are throwing out lava, and 

 how much they have thrown out in historical times. 



7thly. The different earthquakes which man has wit- 

 nessed, how they have broken and dislocated the land, rais- 

 ing it in some places, as in New Zealand, and causing it to 

 sink in others, as at New Madrid, in America. 



Sthly. The way in which plants and animals are buried 

 in the mud of lakes, or at the mouths of rivers, or in peat and 

 sand. 



All these and many other changes which are taking place 

 all over the world in the present day, Lyell studied with great 

 accuracy, and then began to accumulate all this evidence 

 in a work showing that what we find in the rocks might 

 all have been produced by such causes as these, without 

 imagining any extraordinary violence of nature. 



While writing this book he went with another celebrated 

 geologist, Murchison, to Italy and Sicily, and there he 

 studied not only the rocks which the volcanoes of Vesuvius 

 and Etna have been building up for ages, but also saw 

 at Syracuse and other places enormous beds of limestone 

 filled with shells of kinds which may still be found living. 

 The immense thickness of these limestone beds, amounting 



