SCIENCE AT THE BEGINNING OF THE CENTURY 



have. It is furnished by every bed of limestone, every 

 outcropping fragment of fossil-bearing rock, every strati- 

 fied cliff. Ho\v else than through such formation in an 

 ocean-bed came these rocks to be stratified i How else 

 came they to contain the shells of once living organisms 

 embedded in their depths? The ancients, finding fossil 

 shells embedded in the rocks, explained them as mere 

 freaks of " nature and the stars." Less superstitious 

 generations had repudiated this explanation, but had 

 failed to give a tenable solution of the mystery. To 

 Hutton it is a mystery no longer. To him it seems 

 clear that the basis of the present continents was laid in 

 ancient sea-beds, formed of the detritus of continents 

 yet more ancient. 



But two links are still wanting to complete the chain 

 of Button's hypothesis. Through what agency has the 

 ooze of the ocean-bed been transformed into solid rock ? 

 And through what agency has this rock been lifted 

 above the surface of the water, to form new continents? 

 Hutton looks about him for a clew, and soon he finds 

 it. Everywhere about us there are outcropping rocks 

 that are not stratified, but which give evidence to the 

 observant eye of having once been in a molten state. 

 Different minerals are mixed together; pebbles are 

 scattered through masses of rock like plums in a pud- 

 ding; irregular crevices in otherwise solid masses of 

 rock so-called veinings are seen to be filled with 

 equally solid granite of a different variety, which can 

 have gotten there in no conceivable way, so Hutton 

 thinks, but by running in while molten, as liquid metal 

 is run into the moulds of the founder. Even the strati- 

 fied rocks, though they seemingly have not been melted, 

 give evidence in some instances of having been sub- 



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