EVIDENCES OF DEPRESSION 6j 



tion of the dated tide marks cut on the cliffs at various periods in 

 the last century and early in the present one, the Swedish geolo- 

 gists have strongly reaffirmed them. 



Interesting examples of recent elevation are believed to occur 

 in the neighbourhood of Washington, D.C. In colonial times 

 Bladensburg and Dumfries could be reached by sea-going ships, 

 but now they are decidedly above tide-level. The change is 

 generally supposed to be due to a silting up of the creeks, but 

 this appears not to be the case, for there is little alluvium resting 

 upon the bed-rock of the channels. 



In many parts of the world are found beaches, raised far above 

 the sea-level, and these point to an elevation of the land. Such 

 raised beaches occur in Scandinavia, Great Britain, the West 

 Indies, the Red Sea, the southern end of South America, and 

 elsewhere. In these beaches are often found the remains of 

 marine animals, shells, corals, barnacles, and the like, and where- 

 ever such remains occur in undisturbed position, they prove con- 

 clusively either that the land has been upheaved or that the sea 

 has gone down at that point. The form and character of the 

 coast-line itself may be evidence of comparatively recent eleva- 

 tion, as will be explained in Part III. 



Evidences of Depression. — Ancient buildings, which were evi- 

 dently constructed on land, but now are below the sea, show a 

 subsidence at the point where they occur. These are found in 

 several of the Mediterranean lands and on the west coast of 

 Greenland. In the latter country the change is relatively rapid, 

 and has attracted the attention of the inhabitants. 



Buried forests found below the level of the sea indicate subsid- 

 ence. Such forests occur in the Mississippi delta and at many 

 points on the coast of the middle and southern Atlantic States, 

 notably in New Jersey, where the coast is sinking at a rate esti- 

 mated as two feet per century. 



Submerged river- channels are likewise evidences of depression, 

 because a river which flows into the sea cannot excavate its bed 

 below the level of the sea-bottom at its mouth. Many such in- 

 stances are known, but it will suffice to mention the case of the 



