CHAPTER I 

 THE ORIGIN OF THE EARTH 1 



JOSEPH BARRELL 



PROFESSOR OF STRUCTURAL GEOLOGY IN YALE COLLEGE 



INTRODUCTION 



The logic of all branches of science points to the existence 

 of some system of evolution of the universe, its complete 

 nature hidden in the vastnesses of time and space, but never- 

 theless developed in accordance with Nature's laws. The 

 earth is one of the celestial host, its beginnings are bound up 

 with that of other bodies. In the history written in the struc- 

 ture of the earth and in the relations of the earth to the planets, 

 stars, and nebulae lies concealed the story of its genesis. Two 

 chief methods of approach, the geologic and astronomic, lead 

 toward the solution of this fundamental problem. 



The history of the earth is read in the rocks which have 

 been thrust up by internal forces and beveled across by erosion. 

 The nearer events are clearly recorded in the sequence and 

 nature of the sedimentary rocks and their fossils. But the 

 oldest formations have been folded, mashed, and crystallized 

 out of all resemblance to their original nature, and intruded 

 by molten masses now solidified into granite and other 



1 Also presented before the Geological Society of Boston, January 19, 1917. 



Some pages of the following article have been drawn from one by the writer 

 entitled "Origin of the Solar System Under the Planetesimal Hypothesis," pub- 

 lished as Chapter XXV in Pirsson and Schuchert's Text-book of geology, 1915. 

 For permission to use this material grateful acknowledgment is made to the 

 authors and publishers of that work. 



