THE CAUSES OF THE 



XI 



referred. The finer or coarser sediments that 

 are carried down by the current of the river, 

 will only be carried out a certain distance, and 

 eventually, as we have already seen, on reaching 

 the stiller part of the ocean, will be deposited at 

 the bottom. 



Let C y (Fig. 4) be the sea-bottom, y D the 

 shore, x y the sea-level, then the coarser deposit 

 will subside over the region B, the finer over A, 

 while beyond A there will be no deposit at all 



Fig.4. 



and, consequently, no record will be kept, simply 

 because no deposit is going on. Now, suppose 

 that the whole land, C, D, which we have regarded 

 as stationary, goes down, as it does so, both A and 

 B go further out from the shore, which will be at 

 y 1 ; x l , y*, being the new sea-level. The con 

 sequence will be that the layer of mud (A), being 

 now, for the most part, further than the force of 

 the current is strong enough to convey even the 

 finest ddbrix, will, of course, receive no more 



