322 RECENT CHAXGES OF LEVEL 



On our own coast it varies from a few feet, in the neighborhood of New York City, to one 

 thousand or more on the coast of Labrador, and two or three times this amount on the 

 Gi'eenland coast. On the European shore this movement has not yet been proved to 

 increase with the same regularity as we pass to the northward. Something of the kind, 

 however, is distinctly traceable, though the local character of the phenomena is much more 

 decided than in America. For instance, there is some proof of a depression of over a 

 thousand feet in Wales, though northern France shows only slight evidences of very recent 

 submergence. It will be necessary to refer to this local character of the movement in 

 Europe, when we come to consider the cause of the submergence which took jjlace about 

 the time of the glacial period ; for our present purpose it is only necessaiy to urge that the 

 whole coast line of the northern Atlantic, with local exce^jtions, (which we shall see are not 

 diflicult to explain), is marked by indications which show that it is just recovering from a 

 period of great depression. At many points the evidence is pretty clear that this move- 

 ment of elevation is still in progress. It is evident, therefore, that the general character 

 of the changes which have taken place in the iuunediate past in the northern Atlantic, 

 quite harmonizes with the supposition that there is still some change in progress along the 

 coast of North America. At least it may Ije worth while to give the suljject a careful 

 study. In the following section will be found the results of a journey along the coast of 

 Maine, made with the especial intention of observing the evidence of change Avhich might 

 be found there, while the closing section of this Memoir will be given to the considera- 

 tion of the phj'sical causes of the changes of level of shore lines, with sj^ecial reference 

 to the great changes which ushered in the present geological period. 



ox THE PHEJsOlIEXA OF ELEVATIONS' OF THE COAST OF JrAINE. 



Of the three possible conditions of any coast line, elevation, stability, and depression, the 

 former gives by far the clearest evidence of its action. Depression can only be shown by 

 level marks observed at long intervals, or by the existence of a contour of surtace of 

 determined aerial origin beneath the surface of the water. Stability can be shown only Ijy 

 the obscure indications made by the long continued action of water at its point of contact 

 with the land ; extensive submerged tables of rock lying just at the height where the cut- 

 ting action of the water Avould have left them, afford the best evidence of this condition. 

 Elevation, however, is shown, whenever the circumstances are favorable, in a very remark- 

 able manner. The following natural indications of this movement may be taken as valu- 

 able in the order in which they are named, the most trustworthy being given first. 



1. The reuiaius of marine animals lying emljedded in stratified deposits above the level 

 of high tide mark. 



2. The existence of extensive stratified deposits of sand, gravel or mud, at points where 

 fresh water lakes could have had nothing to do with their formation. 



3. The existence of a topography not explicable on any other supposition than marine 

 action above the level of hiii-h tides. 



The first of these proofs cannot be reasonably expected to occur on all shores which have 

 been recently elevated. Even at the present time a good deal of the shore sand and 

 gravels making along our coast are quite wanting in animal remains ; and in the glacial 



