INTRODUCTION. 47 



Interest was directed, in the first place, towards the in- 

 vestigation and description of the accessible parts of the 

 earth's crust. The composition and arrangement of the strata 

 were studied with enthusiasm. The bolder inquirers ventured 

 into wild recesses of mountain-chains and climbed snowy 

 peaks, whose difficulties had hitherto been thought insur- 

 mountable ; travellers explored the uninhabited plains of 

 Siberia, the remote mountain-ranges of Asia and America, 

 and brought home with them new scientific material and 

 observations of the highest importance for comparative re- 

 search. 



The illustrious Professor of Mineralogy at Freiberg, Abraham 

 Gottlob Werner, exercised an unrivalled authority amongst the 

 followers of the strict descriptive method in natural history. 

 By the skill and eloquence of his teaching, far more than by 

 his books and writings, Werner inspired in his scholars and 

 adherents a devotion towards exact methods of study. The 

 public lectures given by Werner systematised for the first 

 time the subject-matter that should properly come within the 

 domain of that rapidly growing branch of science for which he 

 originally suggested the name "Science of Mountains," but 

 afterwards called "Geognosy." Werner included in his system 

 of geognosy the mineralogical identification of the rocks, also 

 the minerals present in them, and their special places of occur- 

 rence, the determination of the stratigraphical position of the 

 rocks, their thickness, and mutual relationships, as well as the 

 conditions under which they took origin. 



Under the term " geology," suggested by De Luc, Werner 

 would only recognise theoretical speculations about the origin 

 and history of the earth. Great though the advantages of 

 Werner's method were, it was not without its weaknesses. 

 The chronological succession of the individual members of a 

 formation was not determined with sufficient precision, the 

 fossils were scarcely used in determining the age of a rock 

 stratum, and the history of organic creation was not even 

 recognised as a subject of investigation in geognosy. 



In this respect the great pioneer was the English engineer, 

 William Smith. He was the first to make known on incon- 

 testable evidence that the stratified rocks of England could be\ 

 most securely identified and arranged in chronological order 

 according to their organic contents. Smith's method of deter- 

 mining the age of rock-strata from the organic remains found 



