164 A CENTURY OF SCIENCE 



America, from her having a corps of mining engineers, who 

 if they had the means, would, in a very short time furnish a 

 work of the same kind, still more complete, of each of the 

 departments. ' ' 



The complete report published in 1833 is a work of 700 

 pages. Pages 465 to 517 are devoted to the subject of 

 granite. Numerous detailed sketches are given showing 

 contact relations. Nine pages are given to theoretical 

 considerations and many lines of proof are given that 

 granite is an igneous rock, molten from the internal heat 

 of the earth, and intruded into the sedimentary strata. 

 His statement is the clearest published in the world, so 

 far as the writer is aware, up to that date, and marks 

 Edward Hitchcock as one of the leading geologists of his 

 generation in Europe as well as America. Unfortu- 

 nately his views were largely lost to sight during the fol- 

 lowing generation. 



In 1840 the first American edition of Mantell's Won- 

 ders of Geology gave currency to the idea that granite is 

 proved to be of all geological ages up to the Tertiary 

 (39, 6, 1840). In 1843 J. D. Dana pointed out (45, 104) 

 that schistosity was no evidence of sedimentary origin. 

 He regarded most granites as igneous as shown by their 

 structural relations, but considers that some may have 

 had a sedimentary origin. 



Rise and Decline of the Metamorphic Theory of Granite. 



Up to 1860 granite was regarded on the basis 

 of the facts of the field as essentially an intrusive 

 rock, but gneiss as a metamorphic product mostly of sedi- 

 mentary origin. It seemed as though sound methods of 

 research and interpretation were securely established. 

 Nevertheless, a new era of speculation and a modified 

 "Wernerism arose at that time with a paper by T. Sterry 

 Hunt, marking a retrogression in the theory of granite 

 which lasted until his death in 1892. 



In November, 1859, Hunt read before the Geological 

 Society of London a paper on "Some Points in Chemical 

 Geology" in which he announced that igneous rocks are 

 in all cases simply fused and displaced sediments, the 

 fusion taking place by the rise of the earth's internal 



