122 



The controversy of these two factions at last reached such a pitch 

 that a new school gradually arose, which professed the utmost indiffer- 

 ence to the views of both parties and determined to devote its labors to 

 observation, ignoring theories entirely unless supported most strongly by 

 facts obtained in the field, and to tliia end the researches of the members 

 of the Geological Society of London, established in 1807, were largely 

 devoted, and at length became instrumental in rescuing the science 

 from the dangerous position into which it had been brought, largely by 

 visionary enthusiasts, both in science and theology. Since the formation 

 of this society, which forms one of the most important epochs in connec- 

 tion -with the progress of the science, the study of geology has proceeded 

 without due regard to the dictates of reason. The assistance of kindred 

 sciences has been evoked, and while of necessity many changes have 

 occurred in the interpretation of the several |>roblems, these changes 

 have been made after careful consideration of all the facts relating 

 thereto, till now geology stands on the proud pedestal as one of the 

 most useful and important of the sciences. 



The generally accepted theory as to the earliest stages of the earth's 

 history is that now known as the " Nebulur Hypothesis." By this it is 

 assumed that not only the earth but all the planets, together with the 

 sun, and in fact all the celestial bodies, first existed as a gaseous mass. 

 This in its revolution around a central axis from time to time threw off 

 huge rings which, partaking of the motion of the original mass, gradually 

 formed by condensation the planetary and stellar bodies, the remain- . 

 ing nucleus of our system still remaining as its sun and centre. The 

 process of condensation and cooling proceeded gi-adiially till in time the 

 first crust of the earth was formed, and became covered with water, 

 gradually also the first land rose from beneath the wave and from this 

 point the beginning of the Geological record must be assumed. While 

 therefore the discussion of this theory would be of great interest 

 as well as of the views regarding the condition of the earth's interior 

 we must be content with this brief notice and consider the divisions 

 of geology proper and moi-e particularly in reference to tliat branch of it 

 known as historical or stratigraphical geology. 



For purposes of convenience it has been found desirable to divide 

 the portion of geological time which elapsed since the formation of the 



