COAST RECORDS OF THE RISE OR FALL OF LAND 253 



with sediment and whose courses can only be followed in sound- 

 ings. One of the most interesting of such channels is that which 

 continues the Hudson River across the continental shelf into the 

 deeper sea (Fig. 283). 



Records of an oscillation of movement. Because a coast 

 is deeply embayed is no ground for assuming that a subsidence 

 is now in prog- 

 ress, or is, in 

 fact, the latest 

 movement re- 

 corded upon the 

 coast. In many 

 cases it is easy 

 to see that such 

 is not the case. 

 The coast of 

 Maine is per- 

 haps as typical 

 of an embayed 

 shore line as 

 any that might 

 be cited, but a 

 study of the 

 river valleys in 

 the neighbor- 

 hood shows clearly that the present submergence of their mouths 

 is a fraction only of an earlier one which has left a record of its 

 existence in beds of marine clay which outline the earlier and far 

 deeper indentations (Fig. 284). 



If now we give a closer examination to the coast, it is found 

 that there are marks of recent uplift in an abandoned shore line 

 now far above the reach of the waves. There is here, then, the 

 record, first of subsidence and consequent embayment, and, later, 

 of an uplift which has reduced the raggedness of the coast outline, 

 exposed the clay deposits, and raised the strands of the period of 

 deep subsidence to their present position. 



In countries which possess a more ancient civilization than our 

 own, the record of such oscillations in the level of the ground has 

 sometimes been entered upon human monuments, so that it is 



FIG. 284. Marine clay deposits near the mouths of the rivers 

 ^ Maine which preserve a record of earlier subsidence (after 

 Stone). 



