$6 PROCEEDINGS OF THE NEW HAVEN MEETING 



On the origin of continents. 1846. 



Geological results of the earth's contraction in consequence of cooling. 

 1847. 



Origin of grand outline features of the earth. 1847. 



In these three papers, it will be recalled, he announced it as his belief that 

 what are now oceanic areas were at one time the more intensely heated por- 

 tions of the earth's crust, and hence had on cooling undergone the greatest 

 amount of contraction and consequent depression ; also that, contrary to the 

 views of the Rogers brothers, the Appalachian uplift could be accounted for by 

 lateral thrust rather than through a force acting from beneath. Further, that 

 the age of the mountains could not be determined by the direction of their 

 trend. These papers I will refer to again. 



On the plan of development in the geological history of North America. 

 1856. 



In this paper he called attention to the now commonly recognized fact that, 

 so far as the American continent is concerned, the greatest mountain chains 

 border on the larger oceans, and that vulcanism is characteristic of these bor- 

 dering chains and oceanic islands rather than continental interiors ; and still 

 again, that oceanic depression and continental uplift have both been in progress 

 with mutual reaction from the beginning of the earth's refrigeration. The 

 original V-shaped character of the North American continent was due to forces 

 acting from the two oceans. 



On some results of the earth's contraction from cooling, including the 

 origin of mountains and the nature of the earth's interior. 1873. 



In this we find Dana once more turning to the subject of his papers of 1847 

 and 1856, and here is well illustrated his capacity for utilizing the work of 

 others. Not contenting himself with mere criticism, he pointed out limitations 

 and errors, if such existed, at times actually strengthening a weak argument 

 and incorporating the whole into his own, adding to it new material to still 

 further bridge the existing chasms. Adopting in part the views of Le Conte, 

 he here recognized the existence throughout a considerable portion of geo- 

 logical time of a thin stratum of liquid matter beneath the crust and a solid 

 nucleus whereby oscillation would be rendered possible. He summed up his 

 conclusions as follows : 



"(1) In mountain-making on continental borders the oceanic crust through 

 its lower portion exercises during the process of crystal contraction an up- 

 ward thrust against the borders of the continent. 



"(2) Among mountain elevations there are those which, like the Alleghanies, 

 are the result of one process of making, or are monogenetic, and those that are 

 a final result of two or more processes at different epochs, or are poly genetic. " 



On a case in which various massive crystalline rocks, including soda- 

 granite, quartz diorite, norite, hornblendite, pyroxenite, and different 

 chrysolitic rocks were made through metamorphic agencies in one meta- 

 morphic process. 1881. 



On the decay of quartzite and the formation of sand, kaolin, and crys- 

 tallized quartz. 1884. 



