1889.] THE DISPLACEMENT OF BEACH-LINES. 15 



in these latitudes would also become lower, owing to the action 

 of denudation, whilst in higher latitudes the rising sea would 

 protect the shores, in such latitudes, from being acted on by de- 

 nudation; and in this way alone the Earth would always, owing 

 to the denuding forces, obtain a form that constantly corre- 

 sponded to it's rotation. But that is evidently not the case. 

 Suppose, for instance, the Earth to be formed of ellipsoidal layers 

 having an increasing density inwards. When the centrifugal 

 force diminished the equilibrium would become, in consequence, 

 disturbed throughout the entire mass, and in the interior the 

 strain would steadily rise. Indeed, not even on the surface can 

 denudation alter the oblateness, because we now know, from the 

 modern investigations of the deep seas, that into these deep 

 oceans, far from the continental shores, none of the disintegrated 

 substances are carried out. Volcanic ashes and cosmic dust 

 alone are deposited. Therefore, the action of denudation is not 

 even sufficient to level the inequalities of the Earth's surface; 

 still less the internal strain that the lengthening of the day 

 produces. And, therefore, if the day has become considerably 

 increased, the sea ought to have become collected at the poles 

 and the land at the equator, if the solid Earth had not altered 

 its form. 



Others think that the Earth really must alter its form. 

 The first to give expression to this is, as far as I can trace, 

 Herbert Spencer. He wrote in the Philosophical Magazine (Lon- 

 don 1847 p. 194) a short Paper: „The form of the Earth no 

 proof of original fluidity in which he contends that eveu the 

 solid earth must alter its form if the centrifugal force becomes 

 changed. When a body increases in size its power of resistance 

 to rupture alone increases with the square of its dimensions, 

 whilst the tendencies to rupture increase in the same proportion 

 as the mass of the body, and therefore as the cube of the di- 

 mensions. When the size increases, we therefore arrive at a 

 point when even the most solid body must yield to the forces 

 acting on it. We must, therefore, Spencer states, assume that 

 the Earth from its size, must yield and alter its form if, for 



