196 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



proposed the term metamorphic rock for the crystalline schists, 

 which he regarded as normal deposits of sand, clay, or lime- 

 stone, subsequently altered in structure by contact with hot 

 eruptive material and by subterranean heat. Thus Lyell in 

 the question of rock-metamorphism at first preserved precisely 

 the attitude of Hutton, but in later years he ascribed the 

 processes of crystallisation partially to mechanical causes, more 

 especially to strong pressure. 



The appearance of Lyell's Principles was epoch-making. 

 Since Werner, no geologist had in such a high degree influ- 

 enced and re-modelled the views of geological science. Al- 

 though, unlike Werner, Lyell did not impart his ideas directly 

 as a teacher, he was personally on terms of intimate acquaint- 

 ance with all the greatest of his contemporaries, and no man 

 could better appreciate the value of the latent currents in 

 scientific thought, nor more skilfully render them intelligible 

 to others. 



Lyell was a master of clear exposition; his writings appealed 

 to a wide public, attracting many to give more serious attention 

 to the study of geology, and establishing it as one of the most 

 popular branches of science. 



Throughout his life he was untiring in his denunciation of 

 any remnants of the unfounded hypotheses promulgated in 

 earlier centuries, and he waged a constant combat against the 

 unscientific fabric of the Catastrophal Theory. He taught 

 the Uniformitarian doctrine of Hutton and Playfair. The 

 earth, in Lyell's opinion, is the scene of never-ceasing change ; 

 but while on the one hand he refused to accept the idea of 

 universal catastrophes, on the other he saw no direct evidence 

 of progress and development in the history of the earth. 

 The Uniformitarian doctrine recognises neither beginning nor 

 end in the earth's history, and opposes just as strongly as the 

 Catastrophal Theory the conception of a progressive evolu- 

 tion. 



Lyell's views were welcomed with enthusiasm in Great 

 Britain, and have there had a lasting influence upon the 

 methods and tendencies of geological research. In Germany 

 also, where Von Hoff had paved the way, Lyell's works 

 attained immediate celebrity, and were made widely known 

 by several translations. But the personal influence of Von 

 Humboldt and Leopold von Buch was still too powerful to 

 allow a rapid acceptance of the Uniformitarian doctrine. 



