T I0 1 he ScottitJi Naturalist. 



foundations in the air, and cannot be propped up without a miracle ; 

 and I undertake, with the assistance of Moro, to explain to you 

 how these marine animals were transported into mountains by 

 natural causes." 



The careful observations of Moro, Gesner and Micheli, of Pallas, 

 Saussure and many others, form a refreshing contrast to the 

 absurd hypotheses of their predecessors ; and in their works, 

 though Palaeontology still occupies the chief place, we see gradu- 

 ally springing up a desire to apply the same methods of reasoning 

 to the phenomena of mineralogy and of structural and dynamical 

 Geology. 



The advent of Werner raised Mineralogy to the chief place among 

 the sciences of the inorganic world. Dynamic Geology received 

 its first scientific exposition at the hands of Hutton and Playfair. 

 Experimental Geology was founded by James Hall ; while Des- 

 marest first grasped the conception of a physical geography of the 

 Earth's surface. But by all these investigators Geology, meaning 

 the study of the structure and mode of origin of the strata of the 

 earth's crust, was looked upon as a subordinate division of the 

 subject to which each was severally devoted. Probably, William 

 Smith, an English surveyor who lived at the close of the eighteenth 

 century, was the first to treat the science of Geology in a truly 

 scientific manner ; certainly it is to his genius that we owe the 

 demonstration of the use of fossils to the Geologist, and the indi- 

 cation of the proper place that Palaeontology should hold in 

 Geological enquiry. 



As now understood, Geology embraces seven more or less dis-' 

 tinct inter-dependent subdivisions. These are : — 



I. COSMOGONY, which treats of the earth as a whole, its re- 

 lation to other heavenly bodies, its own particular movements and 

 probable origin. 



Y\. GEOGNOSY, which describes the constituent parts of the 

 earth, the minerals and rocks of which it is composed. 



III. DYNAMICAL GEOLOGY, which embraces an investi- 

 gation of the operations which lead to the formation, alteration, 

 and disturbance of rocks. 



IV. STRUCTURAL GEOLOGY, which deals with the archi- 

 tecture of the earth, and the mode of arrangements of the various 

 materials composing its crust. Structural Geology is thus the 

 statical aspect of Dynamical Geology. 



