6 INTRODUCTION 



posure of rocks yields him material. It might seem that, at best, 

 his studies must be very superficial, and that he must soon eke 

 out his scanty facts with daring guess-work. Such is happily not 

 the case. The fact that rocks of different ages were formed in 

 different places, and that great disturbances have so tilted immense 

 bodies of rocks that their edges are exposed to view, enables the 

 observer to study vast thicknesses of them, without descending 

 below the surface of the ground. Seventy-five years ago Playfair 

 saw and expressed this truth. " Men can see much further into 

 the interior of the globe than they are aware of, and geologists are 

 reproached without reason for forming theories of the earth, when 

 all they can do is but to make a few scratches on the surface." 



The history of the earth has been recorded, for the most part, 

 upon its successive surfaces, and it is not necessary to penetrate 

 deep into the interior of the globe. In later chapters we shall 

 learn how these surfaces came to be buried to great depths and 

 yet retained the characters impressed upon them when they were 

 superficial in position, as written pages are buried under fresh 

 accumulations of manuscript. This fact, together with the dis- 

 turbances which have made the deep-seated rocks accessible to 

 study, renders the task of deciphering the record less hopeless 

 than might be imagined. 



The study of geology must be carried on at first hand, and 

 cannot be adequately learned from books alone. The use of 

 books is to serve as guides in directing the learner in what to 

 look for and to enable him to compare distant lands with his 

 own. The arrangement and treatment of such a complex subject 

 as geology cannot avoid a certain artificial character, which will 

 surely mislead the student, unless he learns to observe and reason 

 for himself. Some parts of our country are more favourable to 

 geological study than others, but none is entirely devoid of geo- 

 logical interest, and the operations of the dynamical agencies may 

 be watched everywhere. To one who thus familiarizes himself 

 with the structure and history of the country, every landscape 

 will offer a renewed charm and interest. The study of the rocks 

 will lead him step by step to the widest outlook over the history 



