SUBMARINE MOUNTAINS 93 



overthrust of slice on slice, each composite mass sank under 

 its own weight, down to levels in the earth's body where 

 higher temperatures prevail. Hence heat has been conducted 

 into the root, which is therefore slowly expanding — expanding 

 vertically, with uplift of the surface of the thickened sial. If 

 the sialic root or the depressed simatic rock beneath it is actu- 

 ally melted by the heat, there is additional expansion and 

 uplift of the surface. It is the opinion of the present writer, 

 based on a century of study of mountain chains by the geolog- 

 ical profession, that under all of the chains there has been 

 re-melting of sialic rock on a grand scale. Since much of the 

 earth's sialic layer is made of ancient granite, the re-melting 

 gives new, liquid granite, and this hot, mobile material can- 

 not fail to invade its own roof. Moreover, because of its rel- 

 atively low density, the new melt must tend to push up that 

 roof. Out of a world of actual illustrations only one will be 

 cited. 



There is reason to think that the peerless height of the 

 Himalaya is in part due to the former invasion of its solid 

 root by a mass of comparatively light, molten rock. The top 

 part of Mount Everest, its celebrated culminating peak, is 

 nearly six miles above sealevel, but is made of limestone which 

 was originally deposited below that level. The intense Hi- 

 malayan deformation of the earth's crust was most pronounced 

 during the early part of the Tertiary Era. The upheaval of the 

 tortured mass was much later. With the gravimeter and 

 plumb-line geodesists have proved the lofty range to be in 

 balance with the low ground of peninsular India, Siberia, and 

 other broad regions in Asia. The stable arrangement finds ex- 

 planation if we postulate not only a thick root of sialic rock 

 under the range but also a huge body of underlying, intrusive 

 granite which is still hot and expanded, if not partially molten. 

 This possibility is not purely speculative, for in the deeper valleys 



