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25. — The Study op Geology. 

 By J. Logan Lobley, F.G.S., F.R.G.S. 



[A Lecture delivered 13tli March, 1879.] 



In' endeavouring to explain the precise object and scope of 

 geological investigation and study, I cannot do better than make 

 use of the definition given by one of our greatest geologists, Sir 

 Charles Lyell : "Geology is the science which investigates the 

 successive changes that have taken place in the organic and in- 

 organic kingdoms of Nature ; it inquires into the causes of these 

 changes and the influence which they have exerted in modifying 

 the surface and external structure of our planet." This is the 

 technical or restricted and modern meaning of Geology. 



But let us, for a moment, consider the full and widest significa- 

 tion of the word Geology. It is composed or made up of two Greek 

 words — 777, meaning the earth ; and \oyos, meaning a description 

 or discourse about anything. Geology, therefore, in its most 

 extended signification, includes a study of everi/thing relating to the 

 earth — its origin, as well as the phenomena which we now observe ; 

 its place in the universe, as well as its internal structure ; the ar- 

 rangement of the divisions of the surface, as well as that of the 

 rocks of which the continents and islands are composed ; the study 

 of its ultimate elements, as well as that of its constituent minerals ; 

 and, indeed, even the study of the organisms to which the great 

 mother-earth has given life. But the study of that which relates 

 to the origin of the earth is included in Cosmogony, and all that 

 relates to the position of the earth in the universe we call Astronomy. 

 The study of the divisions of the surface is termed Geography, and 

 the science that has to do with the composition of the matter 

 forming the earth, and the properties of ultimate elements, is 

 Chemistry ; while we call by the names Zoology and Botany those 

 departments of science which are devoted to the study of animals 

 and plants. As geologists, we give our attention to those facts, 

 phenomena, and appearances connected with the earth which ai'e 

 not taken cognizance of by any of the sciences I have just named. 

 In other words, and to be explicit, Geology embraces the study of 

 the rocks, their arrangement, contents, structure, and composition, 

 and of the elevations and depressions of the earth's surface. It 

 investigates the causes of the phenomena observed, and so inquires 

 into the changes which have occurred since the origin of the 

 globe, and which have had for their result the production of 

 the earth as we now find it. 



Geology thus restricted is, however, sufiiciently comprehensive to 

 admit of being divided into several departments. The department 

 of the science which relates to the properties, arrangement, struc- 

 ture, and peculiarities of rocks, is called Petrology, from rieTpos, a 

 rock, and Koyo%, a description. The study of the organic contents of 

 rocks, or the remains of animals found in the earth, and called 



