40 
RELATION OF ONSTRATTFIED 
of rotation, shows that this axis has been the 
same ever since the crust of the earth attained 
its present solid form. 
Assuming that the whole materials of the 
globe may have once been in a fluid, or even a 
nebular state,* from the presence of intense 
heat, the passage of the first consolidated por- 
tions of this fluid, or nebulous matter, to a solid 
state may have been produced by the radiation 
of heat from its surface into space ; the gradual 
abstraction of such heat would allow the particles 
of matter to approximate and crystallize; and 
the first result of this crystallization might have 
been the formation of a shell or crust, composed 
of oxidated metals and metalloids, constituting 
various rocks of the granitic series, around an 
incandescent nucleus, of melted matter, heavier 
than granite ; such as forms the more weighty 
substance of basalt and compact lava. 
It is now unnecessary to dwell on controver- 
sies which have prevailed during the last half 
century, respecting the origin of this large and 
important class of unstratified crystalline rocks. 
* The nebular hypothesis offers the most simple, and therefore 
the most probable theory, respecting the first condition of the 
material elements that compose our solar system. Mr. Whewell 
has shown how far this theory, supposing it to be established, 
would tend to exalt our conviction of the prior existence of 
some presiding Intelligence.— Bridgewater Treatises, No. III. 
Chap. vii. 
