564 THE JOURNAL OF GEOLOGY. 



I believe can be removed ; but others perhaps cannot in the pres- 

 ent condition of science, and may indeed eventually prove fatal. 

 Time alone can show. I state briefly some of these -objections. 



1. Mathematical physicists assure us that on any reasonable 

 premises of initial temperature and rate of cooling of the earth, 

 the amount of lateral thrust produced by iuterior contraction 

 would be wholly insufficient to account for the enormous fold- 

 ings. 1 Let us admit — surely a large admission — that this is 

 so. But this conclusion rests on the supposition that the whole 

 cause of interior contraction is cooling. There may be other 

 causes of contraction. If cooling be insufficient, our first duty is 

 to look for other causes. Osmund Fisher has thrown out the 

 suggestion (a suggestion by the way highly commended by 

 Herschel) that the enormous quantity of water vapors ejected 

 by volcanoes and the probable cause of eruptions is not meteoric 

 in origin as generally supposed, but is original and constituent 

 water occluded in the interior Magma. 2 Tschermak has con- 

 nected this escape of constituent water from the earth with the 

 gaseous explosions of the sun. 3 Is it not barely possible 

 that we may have in this an additional cause of contrac- 

 tion, more powerfully operative in early times but still continuing ? 

 See the large quantity of water occluded in fused lavas to be 

 " spit out" in an act of solidification! But much still remains in 

 volcanic glass which by refusion intumesces into lightest froth. 

 Here then, is a second possible cause of contraction. If these 

 two be still insufficient, we must look for still other causes before 

 rejecting the theory. 



2. Again : Dutton 4 has shown that in a rigid earth it is impossi- 

 ble that the effects of interior contraction should be concentrated 

 along certain lines so as to form mountain ranges, because this 

 would require a shearing of the crust on the interior. The yield- 



'Cam. Phil. Trans. Vol. XII., Part II., Dec. 1873. 



Cambridge Phil. Trans. Vol. XII., Part II., Feb. 1875. Physics of the Earth's 

 Crust, p. 87. 



3Geol. Mag. Vol. IV., p. 569, 1877. 



4 Am. Jour. Vol. VIII., p. 13, 1874. Penn. Monthly, May, 1876. 



