560 REPORT OF NATIONAL MUSEUM, 1904. 



upon which they were deposited. Finally, this softening would be 

 sufficient to cause a yielding to horizontal pressure along the line, and 

 a consequent upswelling of the line into a chain. Even the granitic 

 axes of mountain ranges might, he thought, in most cases be but the 

 lowermost, and, therefore, most highly metamorphosed portions of the 

 squeezed mass, exposed by erosion. 



He agreed with Richthofen and Whitney that the great masses of 

 lava, often constituting the chief bulk of mountain chains, had not 

 come from craters but from fissure eruptions, and that volcanoes are 

 themselves only secondary phenomena, produced by the access of 

 meteoric water to the still hot interior portions. He did not, how- 

 ever, agree with them in assuming that this iluidal mass was a part of 

 a universally incandescent liquid interior, but rather a submountain 

 reservoir locally formed. He felt that this theory, while not dependent 

 upon, was powerfully supported by, the views of Ro.se, Bischoff, and 

 others as to the metamorphic origin of granite and other igneous 

 rocks, a view which regarded the surface materials as having passed 

 by perpetual cycles through all the stages of rocks and soils — igneous 

 rocks disintegrated to soils carried away and deposited as sediments; 

 consolidated into stratified rocks; metamorphosed into gneiss, granite, 

 or even lavas; to be again, after eruption, reconverted into soils, and 

 recommence the same eternal round. 



In furtherance of these same views, Le Conte in 1876 gave, in the 

 American Journal of Science, the results of observations made in the 

 Coast Range Mountains of California along the line of the Central 

 Pacific Railroad. He found the largely unaltered rocks here thrown 

 into a series of anticlines and synclines with angles of dip varying 

 from 65° to 70°. From this he estimated that the original matter as 

 deposited on a sea bottom must, in the building of the range, have 

 been crushed from a breadth or width of 15 to 18 miles into 6 

 miles, with a corresponding upswelling of the whole mass. In 1878 

 Le Conte had another paper in the same journal' on the same sub- 

 ject, in which he argued that mountain ranges are always formed by 

 horizontal pressure, and that this pressure on a large scale could be 

 produced only by the interior contraction of the earth. To overcome 

 the objections raised by some to this theory to the effect that interior 

 contraction could not concentrate its manifest results along certain 

 lines without such a slipping- and shearing as is impossible in a solid 

 earth, he conceived the presence of a solid nucleus and a solid crust 

 separated by a zone of fused or semifused matter. To an objection 

 that contraction based upon shrinkage alone was inadequate to pro- 

 duce the evident results, he argued that there might be other causes, 

 such as loss of water in form of vapor by volcanic action, and still 

 others concerning which as yet nothing was known. His theory of 

 origin, as he here summed it up, consisted of three stages: (1) A stage 



