DISSOLUTION. 539 



the grinding actions of glaciers, they have their particles 

 gradually separated, carried away, and widely dispersed. 

 Or when, as otherwise happens, the encroaching sea reaches 

 them, the undermined cliffs which they form fall from time 

 to time, breaking into fragments of all sizes; the waves, 

 rolling about the small pieces, and in storms turning over 

 and knocking together the larger blocks, reduce them to 

 boulders and pebbles, and at last to sand and mud. Even if 

 portions of the disintegrated strata accumulate into shingle 

 banks, which afterwards become solidified, the process of 

 dissolution, arrested though it may be for some enormous 

 geologic period, is finally resumed. As many a shore shows 

 us, the conglomerate itself is sooner or later subject to the 

 like processes; and its cemented masses of heterogeneous 

 components, lying on the beach, are broken up and worn 

 away by impact and attrition — that is, by communicated 

 mechanical motion. 



When not thus affected, the disintegration is effected by 

 communicated molecular motion. The consolidated stra- 

 tum, located in some area of subsidence, and brought down 

 nearer and nearer to the regions occupied by molten matter, 

 comes eventually to have its particles brought to a plastic 

 state by heat, or finally melted down into liquid. Whatever 

 may be its subsequent transformations, the transformation 

 then exhibited by it is an absorption of motion and disinte- 

 gration of matter. 



Be it simple or compound, small or large, a crystal or a 

 mountain chain, every inorganic aggregate on the Earth, 

 thus, at some time or other, undergoes a reversal of those 

 changes undergone during its evolution. Not that it usually 

 passes back completely from the perceptible into the imper- 

 ceptible; as organic aggregates do in great part, if not 

 wholly. But still its disintegration and dispersion carry 

 it some distance on the way towards the imperceptible ; and 

 there are reasons for thinking that its arrival there is but 

 delayed. At a period immeasurably remote, every such 



