THE CRUST OF THE EARTH. 



example of a submerged forest on the western coast of America. 122. 

 Temple of Jupiter Serapis. 123. Historical researches of Professor 

 Forbes. 124. Tradition of a submerged city under Lough Neagh. 



125. Why these undulations of the earth's crust might be expected. 



126. Effects of disruption of the crust. 127. Volcanic eruptions of 

 1808 in the Azores. 128. The Monte Nuovo. 



100. THE formation of cracks and fissures in the crust of the 

 globe has been ingeniously explained by M. Elie de Beaumont, as 

 the natural and necessary consequence of the process of superficial 

 cooling taking place upon a globular mass of matter in a state of 

 fusion. 



To render intelligible the reasoning and theory of this eminent 

 geologist and naturalist, let us suppose the globe, as we have for- 

 merly described it, to have been originally in a state of igneous- 

 fusion, and to undergo a gradual superficial cooling, by which a thin 

 solid shell would be formed upon it. The contraction of this shell, 

 taking place from its inner towards its outer surface, would leave 

 a vacant space between the central mass in fusion and the concave 

 interior surface of the solid shell. Supposing also, as we have 

 formerly explained, that after tho external surface had fallen below 

 the temperature which maintains water in a state of vapour, the 

 atmospheric vapours, being condensed, had fallen in rain ; the ex- 

 ternal surface of the terrestrial spheroid would then have been 

 covered with an ocean of uniform depth and would consequently 

 have been totally destitute of land. 



An imaginary section of a part of the terrestrial crust in thi& 

 state is represented in fig. 41, where b is the solid crust, a the 

 liquid central mass, d the intermediate vacant space, and c the 

 ocean of uniform depth covering the entire surface. 



Fig. 41. 



a 



But the state of equilibrium which would maintain this state 

 of things could not continue. The internal fluid matter would 

 press more or less upon the thin crust surrounding it, which being 

 unequal in its structure, would offer proportionately unequal re- 

 sistance, and consequently yielding at its weakest points would 

 be dislocated as shown in fig. 42, the fragments being thrown 

 into infinitely various positions. Thus the piece f being tilted 

 obliquely, would be raised at one end above the surface of the 

 ocean, depressed at the other. It would, therefore, form a chain of 

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