412 



F. P. GULLIVER — CUSP ATE FOKELANDS. 



. HO. - - 



■RUMPET). 6 8T 



"^ West Point 



The cusp is very perfectly formed by the intersection of the two curves 



in a sharp point. 



Plate 18 (facing page 399) represents a cusp in Narragansett bay which 



is nearly as typical in form and position as West point. Sand point pro- 

 jects from the eastern side of 

 Prudence island (C. S., 353) 

 into a cliannel less than two 

 miles broad and from 10 to 

 17 fathoms deep, 5] fathoms 

 off the point of the foreland. 

 Tliis cusp is smaller than the 

 average tidal cus}) and it 

 shows no included lagoon or 

 marsh. Mr J. B.Wood worth, 

 for whom the photograph was 

 taken, says that the ice in 

 winter overrides this 'cusp 

 and thus any indications of 

 (Mnl)ryonic form would be 

 ()])literated. - The secondary 



VioUKK-:,.-Typet,dal Cuspate Fan-laud. ^USp OU the Icft sidc of thc 



foreland appears to be due to tlie collection of sand about rocks or i)iles. 



The view is taken from the cHff south of thc foreland looking northeast.* 



A profile has been drawn from anotlicr typical cusp, ]ioint Wilson (C. 



S., 6405), north of Port Townsend, Wasliington. This drawing (figure 6) 





SL 



'/r 



J Kilomefres. 



l-'iGURiv 6.— Profile tidal Cusp. 

 The ratio of the vertical to the horizontal scale is 2 to i. 



shows the relation of tlie forehmd to the older mainhxnd. The l)roken 

 line indicates the probable initial form of the land following the depres- 

 sion which inaugurated the present cycle of shore development. The 

 " foreland " quality of the cusp is here clearly seen. It is constructed by 

 transportation and accumulation in front of the nipped oldland. Al- 

 though plotted from the soundings and contours about point Wilson, 

 this figure will serve as a general profile of all the cusps of this class. 



* Taken by Mr P. P. Sliarples and published by permission of ihe Director of the United States 

 Geological Survey. 



