FIELD GEOLOGY. 



greater is felt to be the need of a Manual which shall 

 teach the practical procedure in the field and elsewhere. 

 A great majority of the manuals of Geology, although 

 excellent as guides to a theoretical knowledge of the 

 science, do not sufficiently describe the methods of obser- 

 vation in the field. Without such proper method much 

 time is wasted, many results that otherwise would have 

 been valuable are entirely lost, and the student finds 

 that his labours do not yield to him a proportionate 

 amount of beneficial knowledge. 



To facilitate the acquirement of such knowledge, this 

 work has been published not as containing very much 

 that is original, but as embodying in a small compass 

 practical directions and suggestions which are to be 

 found here and there only in more important works. 

 The object has been to bring them with some additions 

 which are the result of practical experience into a form 

 which shall be at once portable and adapted to special 

 reference. 



If we would make a series of drawings that shall shew 

 the geological structure of any district, it is not sufficient 

 that we are versed in theoretical geology, nor even that 

 we can walk into a quarry and say, " This is a Lime- 

 stone," or a "Sandstone" as the case may be and 

 "it belongs to this or that Formation." We must be 

 able to trace out its boundary, to shew the area that it 

 occupies, and to ascertain the angle at which it dips be- 

 neath the surface. When these points are determined 

 in regard to a series of strata, we have a geological Map, 

 or surface projection and aided by our notes, we can 

 construct therefrom a geological Section, which shall 

 shew the underground extension of the rocks, their thick- 



