ORIGIN OF ERUPTIVE AND PRIMARY ROCKS. 



J21 



Hunt inclines also to the supposition that the centre of the 

 earth is solid, although he is of opinion that the fluid matter 

 resting above it is altogether of sedimentary origin, and is in a 

 state of igneo-aqueous fusion. He remarks "that beneath the 

 outer crust of sediments, and surrounding the solid nucleus, we 

 may suppose a zone of plastic sedimentary material adequate to 



explain all the phenomena hitherto ascribed to a fluid nucleus." 

 (American Journal of Science for May, 1861.) If, further, iron 

 when fused loses its magnetic power, and the phenomena of mag- 

 nism on the surface of the earth can be explained on the supposi- 

 tion that the metallic centre has assumed the solid form, then this 

 supposition would appear to be very reasonable indeed. It would 

 of course be impossible to assume that the metals have not only 

 Can. Nat. 21 Vol. VIII. 



