24 



INTRODUCTION. 



When for the first time in our lives we decide to give some 

 attention to geology, we find that much hard study is neces- 

 sary before the grand principles of the science are compre- 

 hended. Not only must we read one, or more of the leading 

 Manuals, but we must go into the field, and examine for our- 

 selves, in quarries, cliffs, and cuttings, the nature and arrange- 

 ment of the rocks.^ 



4s.i^ 



Equipped with map, note-book, hammer, compass, clinometer, 

 pocket-lens, and pen-knife ; and with also a bag, and small bottle 

 of hydrochloric acid, the geological student would be prepared for 

 work of all kinds. The clinometer will be useful for registering 

 the 'dip' or angle of inclination of the strata. The pocket-lens 

 will be of service in determining whether the rock be crystalline or 

 composed of a mechanical aggregate of rounded or angular frag- 

 ments. The pen-knife will, by its determination of hardness, 

 indicate a very siliceous from a calcareous rock. Hydrochloric 

 acid (diluted to iV) will be useful in detecting the limestones and 

 marls. 



Following in the footsteps of William Smith, the main out- 

 lines of the geological structure of our country were sketched 

 by Sedgwick, Webster, Buckland, Conybeare, Fitton, De la 

 Beche, Murchison, Mantell, Lonsdale, and John Phillips. To 

 De la Beche we owe the establishment of our Geological 



^ The principal modem Manuals of Geology are those by A. Geikie (two 

 separate works), J. Geikie, A. H. Green (Physical Geology), A. J. Jukes-Browne 

 (2 vols ), J. Prestwich {2 vols.), H. Seeley and R. Etheridge (2 vols.). See also 

 Text Book of Field Geology, by W. H. Penning, edit. 2, 1879 (Paleontology, 

 by A. J. Jukes-Browne) ; A. Geikie, Outlines of Field Geology, edit. 3, 1882. 



