DAVIS. — OUTLINE OF CAPE COD. 315 



are accustomed to study transportation and deposition as submarine 

 processes, but little attention has been given to decomposition, disin- 

 tegration, corrasion, or any other process by which the sea floor is 

 degraded. The subject deserves careful investigation. 



It is manifest from the preceding paragraplis tliat a graded profile 

 may be attained much earlier on one part of a shore line than on 

 another ; for the texture, the original profile, and the exposure of a 

 coast all vary from place to place. But in a region like Cape Cod, 

 where the original shore line consisted wholly of uncompacted mate- 

 rials, this aspect of the problem need not be considered further. 



Development of Shore Outlines. 



It is not, however, only in on-and-o£E-shore action that a close com- 

 parison may be drawn between the operations of marine and fluviatile 

 agencies. The 'long-shore action of the sea also is in many respects 

 comparable to the down-stream action of rivers. Beginning on an 

 unevenly deformed land surface in a region of moderate rainfall, 

 where there are many heights and hollows, the drainage will at first 

 consist of many small independent systems, each one transporting waste 

 from the initial divides down the initial slopes into the initial hollows. 

 Every stream proceeds, by degrading and aggrading its course, to 

 develop a line of slope on which its ability to do work shall every- 

 where equal the work that it has to do. As the eminences are worn 

 down and the hollows are filled up, local systems that were at first 

 independent become confluent, and the drainage of the higher ones 

 is discharged to the lower ones. Every change of this kind will call 

 for rearrangement of the degraded and aggraded slopes in the con- 

 fluent basins. Ultimately, all the separate systems will, in one combi- 

 nation or another, find outlet to the sea, and the waste will be carried 

 a long distance from the main divides to the main river deltas. 



It is much the same with the action of the sea. Leaving the on- 

 and-otf-shore action out of consideration for the moment, let us view 

 only the 'long-shore action, as determined by the dominant rather than 

 by the prevailing movements of the littoral waters. The projections 

 or headlands of the constructional shore line act as so many divides, on 

 either side of which the 'long-shore currents flow away from the apex, 

 as in the uppermost outline in Figure 3. The re-entrants or bays are so 

 many basins into which the 'long-shore currents converge from the ad- 

 jacent headlands. The headlands are slowly worn back, and the waste 

 is carried along their sides into the bays, where it forms aggrading 



