chap. yiii. Elevation Gradual. 217 



gravel-capped plains can be explained quite as well, as 

 by the more obvious view already given of a few com- 

 paratively great and sudden elevations ; in either case 

 we must admit long periods of rest, during which the 

 sea ate deeply into the land. Let • us suppose the 

 present coast to rise at a nearly equable, slow rate, yet 

 sufficiently quick to prevent the waves quite removing 

 each part as soon as brought up ; in this case every 

 portion of the present bed of the sea will successively 

 form a beach-line, and from being exposed to a like 

 action will be similarly affected. It cannot matter to 

 what height the tides rise, even if to forty feet as at 

 Santa Cruz, for they will act with equal force and in 

 like manner on each successive line. Hence there is 

 no difficulty in the fact of the 355 feet plain at Santa 

 Cruz sloping up 108 feet to the foot of the next highest 

 escarpment, and yet having no marks of any one par- 

 ticular beach-line on it ; for the whole surface on this 

 view has been a beach. I cannot pretend to follow out 

 the precise action of the tidal waves during a rise of 

 the land, slow, yet sufficiently quick to prevent or check 

 denudation : but if it be analogous to what takes place 

 on protected parts of the present coast, where gravel is 

 now accumulating in large quantities, 1 an inclined 

 surface, thickly capped by well-rounded pebbles of 

 about the same size, would be ultimately left. On the 

 gravel now accumulating, the waves, aided by the wind, 

 sometimes throw up a thin covering of sand, together 

 with the common coast-shells. Shells thus cast up by 

 gales, would, during an elevatory period, never again 

 be touched by the sea. Hence, on this view of a slow 

 and gradual rising of the land, interrupted by periods 



1 On the eastern side of Chiloe, which island we shall see in the 

 next chapter is now rising, T observed that all the beaches and exten- 

 sive tidal flats were formed of shingle, 



