INTRODUCTION 



Geology is the study of the earth's history and development, as re- 

 corded in the rocks, and of the agencies which have produced that 

 develop??ie?it. 



From this definition it appears that the central problem in geol- 

 ogy is the deciphering of the earth's history, and that the historical 

 standpoint is the dominant one. Geology deals with the earth as 

 a cosmical unit, and is a great synthesis of all those sciences which 

 throw light upon the structure of the globe and which may be used 

 in interpreting its records. Astronomy, physics, chemistry, miner- 

 alogy, physical geography, zoology, and botany are all drawn upon 

 for this purpose. The goal of our inquiries is the history of the 

 earth as a whole, and not of a single continent merely. We should 

 endeavour to gain a true insight into those great processes of 

 development which control the whole visible universe, and which 

 exhibit in the most impressive way the great principles of order 

 and of uniformly acting laws. It is, however, necessary to make 

 a selection from the immense body of ascertained facts, and it is 

 clearly advantageous that, so far as possible, we should make use 

 of our own country for this purpose. It must always be remembered 

 that the instances chosen from familiar scenes are but illustrations 

 and examples of world-wide processes and structures. To find 

 active examples of some important phenomena, we must travel to 

 far-distant lands, but even of these we shall find the unmistakable 

 traces in our own continent, as having been at work here at one 

 time or another in the past. 



Geology is one of the most modern of the sciences. In the 

 works of certain classical and mediaeval writers we find, it is true, 



B I 



