VII. 



ON SOME POINTS IN DYNAMICAL 

 GEOLOGY. 



The following paper, which appeared in the American Journal of Science for April, 

 1873, may be read as a supplement to Essays I., II., V., and VI. in the present volume. 

 Nearly all of the views which I have maintained since 1858 - 1861 in my endeavors to 

 reconstruct dynamical geology on a new basis, as set forth in the essays just referred 

 to, have of late been appropriated, without recognition, perhaps unconsciously, by 

 LeConte, Mallet, and others ; and therefore some assertion of priority on my part 

 seemed not out of place. The reader may also consult in this connection Professor J. 

 D. Dana's essay on The Results of the Earth's Contraction on Cooling, in the Ameri- 

 can Journal of Science for June -September, 1873, and further a note in the same 

 Journal for November, 1873 (page 381). containing his acknowledgment of my claims to 

 priority on important points which he had denied me in the essay in question. 



IN his late essay on The Formation of the Features of the 

 Earth's Crust, in the American Journal of Science for Novem- 

 ber and December, 1872, Professor Joseph LeConte has dis- 

 cussed a wide range of subjects in geological dynamics, in a 

 manner for which the student cannot but be grateful. After 

 a consideration of the arguments with regard to the nature of 

 the earth's interior, he arrives at the conclusion that " the whole 

 theory of igneous agencies which is little less than the ?///'//> 

 foundation of theoretic geology must be reconstructed on f/ia 

 basis of a solid earth" ; a conclusion which forms the starting- 

 point of his'essay. It is here to be noted, that the late AVil- 

 liam Hopkins, to whom we owe one of our great arguments in 

 favor of a solid globe, did not take this ground, but sought to 

 explain the phenomena of igneous action by the hypothesis of 

 portions of matter still remaining unsolidified at no great 

 depth between the solid nucleus and the superficial crust. 

 Dissenting from this view, though accepting the general conclu- 



