Shaler.] 132 [October 7. 



of the shore, and the gain of the dry land on the sea. Thus we see 

 that the relative position of the pivotal point to the shore line may 

 produce such apparently contradictory actions as rise and fall of the 

 land. It is evident that the precise position of the pivotal point 

 must be very much a matter of; accident. Trifling causes may effect 

 its removal to such a distance, that in a comparatively brief time, the 

 same region of shore may be just upon the fulcrum point, or to the 

 seaward or landward of it, and thus experience the tlu'ee conditions 

 of permanence, subsidence or elevation. 



The line of no movement, or axis of rotation, would, on account of 

 the great rigidity of the crust, tend to have a rectilinear direction, or 

 at least far fewer curves than usual on shore lines; assuming that it is 

 for limited regions in effect a straight line which may have a consid- 

 erable angle to the general trend of coast, we perceive at once that 

 the resulting movements at different points may be very varied. 



All one extremity of a coast may have a movement in one direc- 

 tion, the middle portion may be stationary, and the other extremity 

 be affected by a movement in the opjjosite direction. Where a shore 

 is deeply indented, the extremity of a cape or promontory may be to 

 the seaward of the axis of rotation, and be on that account sinking, 

 while the main land may be within the axis of movement, and exhibit 

 evidences of elevation. Inspection of the diagrams wdll show how 

 far the relation of the shore line to the axis of rotation can compli- 

 cate the evidences of movement of different points. 



It must not be sujiposed that this hypothesis requires that the sec- 

 tio^^s of the crust from the centre of the sea to the centre of the con- 

 tinents, move as a rigid mass, for on such a supposition we would be 

 obliged to suppose that a movement of a few inches at the shore, near 

 the pivot point, must indicate a movement to the extent of thousands 

 of feet in the central regions of the oceans or continents. It is likely 

 that, as the earth loses heat and contracts, the sea floors subside, 

 and the land areas rise at something like the same rate over their 

 whole surfaces. The general form of both continents and ocean bot- 

 toms makes this supposition seem very probable. 



Without considering the proof of the validity of this hypothesis 

 which would be beyond the authoi-'s purpose at jwesent, it may be 

 noticed that there are many phtenomena better explicable on this view 

 than by any other hypothesis which has been presented. First among 



manner that the points P and P'' may be taken for the pivot points of the diagrams 

 1 and 2. respectively. All that portion of thp shore line to the right of the straight 

 line would be sinking : all to the left rising. 



