P B E F A C E. 



DURIXG the last twenty years immense progress has 

 been made in the dissemination of Geological know- 

 ledge, yet still the old cry, " It is so difficult, so full of 

 technicalities, so hard to be understood." Now, with- 

 out admitting that Geology is fuller of technicalities, 

 or one whit more difficult to be understood, than other 

 sciences, I have thought it worth while, in the present 

 volume, to attempt a simple and familiar exposition of 

 its leading truths and principles. Because some have 

 made the same attempt and failed is no reason why 

 I should not try; because it is fashionable in some 

 quarters to sneer at popular sketches is no reason why 

 I should be deterred from expressing my conviction 

 that sketches of this kind are the only means by 

 which the majority of people can acquire any know- 

 ledge of science, while in many instances they form 

 the first steps even to those who subsequently profess 

 to despise them. Because information is given in a 

 popular way, it need not be inaccurate and flimsy ; 



