THEORY AS TO TIDAL CUSPS CONFRONTED WITH FACTS. 417 



Among these filled cusps are included doubtless those which have 

 passed through the V-bar stage as well as those which have grown by 

 gradual outbuilding, since from present knowledge it is impossible to 

 separate the two groups. With better maps and descriptions of the cusps 

 a later classification will make closer distinctions. 



THEORY CONFRONTED WITH FACT. 



After this general survey of the varying forms of cuspate forelands 

 selected from the many examples in the narrow water bodies of the world, 

 the following generalization may be made : However varied the form 

 resulting from the local conditions, tides, relief of oldland, etcetera, the 

 axis of a line drawn from the point of the cusp through the center of the 

 foreland is always at right angles to the general direction of flow of the 

 tidal currents. 



Where there are strong tides, as in Paget sound, Chesapeake bay, and 

 Narragansett bay, there are numerous and typical cuspate forelands ; 

 while in Albemarle sound the range of tides is less than one foot, and 

 here few sandy points of a cuspate form occur. 



Thus the facts of observation seem to correspond with the principal 

 requirement of the theory. Studies of the existing currents in regions 

 where these forelands are found are now needed to further test the tidal 

 hypothesis. From present knowledge this seems to be the best working 

 hypothesis. 



Two methods of growth are suggested. In one the outline of the fore- 

 land is earl}^ given by a V-bar, and later this inclosed lagoon is pro- 

 gressively filled. In the other the foreland grows by successive additions 

 to the mainland. The first appears to be by far the larger class, though 

 examples of the latter are liable to be confused with the filled stage ot 

 the first class. 



Between the narrow channels and the open sea there are all gradations 

 in size of water bodies, so we should expect to find forelands built by 

 combination in different proportions of tidal and wind currents. Such 

 cases have been referred to above in Del Faro point, Aro island cusp, and 

 Alice point. 



Delta Cusps. 



INTRODUCTORY STATEMENT. 



Rivers in wandering across their alluvial plains often produce along 

 their banks small cuspate points between whirling eddies, which are 

 located along river banks as the tidal cusps are along inland channels. 

 These could hardly be grouped as a class of forelands as the word has 



