38 HISTORY OF THE SCIENCE. 



Playfair. " Amid all the revolutions of the globe," observes 

 the latter, " the economy of nature has been uniform, and 

 her laws are the only things that have resisted the general 

 movement. The rivers and rocks, the seas and the con- 

 tinents, have been changed in all their parts, but the laws 

 which direct these changes, and the rules to which they are 

 subject, have remained invariably the same."* 



The most distinguished opponent of "Werner in this 

 country, was DR. HUTTON, a Scottish physician, whose 

 opinions, on all essential points, were the very reverse of 

 those of the professor of Freyberg, 



As the substance of his theory, which has been designated 

 the PLUTONIAN, he taught the following important truths : 



First, that no geological phenomena afford any proof of 

 the beginning of things. 



Secondly, that the oldest rocks are merely derivative com- 

 pounds of the ruins of rocks which existed before them, and 

 which were destroyed, chiefly by the slow action of atmo- 

 spheric causes ; while their detritus, borne by rivers to the 

 ocean, and loosely strewed over its bed, became consolidated 

 by heat, and subsequently upheaved and fractured. 



Thirdly, that the metamorphic rocks were originally 

 sedimentary deposits, similar to the secondary, but that they 

 have been altered by the long-continued action of heat. 



Fourthly, that granite has crystallised from a state of 

 igneous fusion, under conditions of heat and pressure. In 

 other words, that it has been melted by fire, at great depths 

 in the earth, and has cooled under pressure so vast as 

 to have prevented the gaseous portions of its elements 

 from escaping, and has thus assumed its present crystalline 

 texture. 



Such is an outline of the celebrated system of Dr. Hutton, 

 which has not only supplanted that of Werner, but has 

 formed the foundation of the researches and writings of our 

 most enlightened observers, and is justly regarded as the 

 basis of afl sound geology at the present day. 



If we examine the above propositions in detail, we shall 

 only find them to have been confirmed by repeated investi- 

 gation. The crystalline texture and igneous origin of granite 



* Illustrations of the Huttonian Theory, 37. 



