GEOLOGICAL DEVELOPMENT OF KANSAS. 



By Lyman C. Wooster. 

 THE RAIN OF PLANETESIMALS. 



THE nebular hypothesis of Kant and Swedenborg has failed 

 to meet the tests applied by modern men of science, and 

 soon will be remembered as being merely one of the dreams 

 of philosophy. Finding that the nebular hypothesis is un- 

 supported by scientific data in many vital parts, the writers 

 of the later scientific texts have substituted the planetesimal 

 hypothesis of Chamberlin, believing that it gives a truer ex- 

 planation of the development of the earth. According to this 

 hypothesis the earth began as one of several nuclei in an arm 

 of a spiral nebula, a form of nebula very common in the 

 heavens at the present time, and has slowly reached her pres- 

 ent size through the accretion of myriads of small planetesi- 

 mals which were drawn in from the neighboring regions of 

 the nebula. 



As the planetesimals accumulated the pressure within the 

 young planet eventually became so great that many absorbed 

 gases were forced from their enclosing cavities and driven 

 to the surface. When the earth had reached nearly her present 

 size the escaping nitrogen and oxygen were recaptured by 

 gravity and remained as an atmosphere; heated hydrogen and 

 oxygen united to form water vapor somewhere in the earth's 

 crust, and on escaping into the atmosphere it cooled and con- 

 densed into rain, which returned to the earth and filled up all 

 the depressions on her surface and became the seas and oceans ; 

 some of the oxygen picked up carbon and became carbon- 

 dioxide gas, which escaped into the atmosphere through fis- 

 sures or volcanoes or bubbled up through the water and became 

 one of the greatest agents in the reconstruction of the earth's 

 surface and one of the substances of the highest importance to 

 the future plants and animals; hydrogen and carbon also united 

 somewhere in the interior of the earth, and possibly became 

 the petroleum and natural gas so highly prized in the arts. 



Footnote. — The limits of this paper forbid giving: more than the story of the geological 

 development of Kansas. The data in full and the scientific arrangement of these data will 

 be found in the various reports and manuals that give the geology of the states occupying 

 the Great Plains. 



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