CHAPTER il.-PROGRESSiVE CHANGE IN NATURE. 



" Nature knows no pause in progress and attaches her curse to all inaction." Goethe. 



A. Origin of the Earth. Concerning the origin of our planet two views may be held. 

 It may have always existed 'and presumably will never end, or it may have been created. If 

 created it must have been by DEITY and two methods might have been employed. It might 

 have been flashed into existence by divine command, illustrating the special creation method; 

 or it may have been produced by slow progressive change. Scientific studies of the solar system 

 and other portions of the universe have led to the belief that the earth was created by the 

 method of slow progressive change and that it must necessarily come to an end. As to the 

 manner of this creation three different theories have been held. 



1. NEBULAR THEORY. Based upon the great nebular masses known to exist in the 

 heavens this theory assumes that the entire solar system (sun, planets and satellites) existed 

 in the form of a white hot gaseous mass. Gravitation gave the mass a spheroidal form and 

 as it radiated its heat into space it contracted and a slow rotary movement was inaugurated. 

 Further contraction increased the rotary movement and the gaseous matter was drawn some- 

 what from the poles and heaped up about the equator, where the motion was the greatest. 

 Ovving to the tendency of a rapidly rotating mass to move from the center (centrifugal force} 

 there came a time when this tendency just balanced the gravitation in a ring of gaseous mat- 

 ter surrounding the equator. This ring then had its weight neutralized and became detached 

 from the central mass as the latter continued to contract from its loss of heat. This ring of 

 gaseous, or semi liquid matter, retained its mass kinetic energy but gave out its heat, cooling 

 and contracting and finally breaking up into fragments all revolving in the same orbit about 

 the great central mass. Because of mutual attractions and unequal velocities the larger masses 

 captured the smaller and eventually all were united into a single rotating and revolving spher- 

 oid of solid matter, the planet Neptune. As the central mass contracted more and more its 

 velocity of rotation continually increased and successively other rings were detached, each be- 

 coming a planet with diminished orbit, the sun representing what is still left of the central 

 mass. According to this theory some of the planets themselves gave off one or more rings 

 which became their satellites, our earth giving off but one. The source of the earth's kinetic 

 and potential energy and internal heat is now apparent. 



Through ages too long to be numbered in years the earth may be supposed to have passed 

 through the gaseous, liquid and partially solid condition. The original crust formed in 

 patches and may have been frequently reraelted, until it finally became continuous. Eventu- 

 ally it became cool enough to allow the condensed water vapor to rest in the irregular depres- 

 sions and the seas were started. How much of the interior of the earth still remains molten 

 we have no means of knowing, but it is supposed that in spite of the heat, the tremendous 

 pressure of the outer layers forces the molecules closely enough together to make a solid of 

 the great central core. 



2. MKTEORITIC THEORY. According to this theory the earth was formed from the 

 accumulation of those wandering rock fragments in space known as meteorites. A large one 

 would draw to itself the smaller ones coming within the sphere of its attraction and these in 

 turn others, until a great central mass would be accumulated. The mass kinetic energy of 

 the flying meteorites would be transformed into heat upon striking, and so the entire mass 

 would become heated and possibly even liquified. The gases and vapors would be driven 

 from the various meteorites and from the atmosphere and seas. From this highly heated 

 spheroidal body the history of the earth would be very similar to that outlined in the preced- 

 ing theory. The rotation of the earth upon its axis may be explained by assuming that the 

 heaviest blows were struck upon the same side of the center. Its movement about the sun 

 may have arisen from its capture by gravitation by that great body, in the same manner that 

 the earth secured its moon. 



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