332 PROCEEDINGS OF THE AMERICAN ACADEMY. 



waves of Cape Cod bay, whose concave sweep along the Truro shore 

 shows their competeuce to do no insignificant share of the work. 



It does not seem at all likely that, while the rest of the Truro main- 

 land is wearing away, the spit at Race point will of itself curve around 

 to the south, and thus save from destruction the narrowing bar which 

 encloses Provincetown harbor on the west. A great volume of trans- 

 ported sand would be needed to continue the bar in the deep water 

 through which its present curve would lead. Moreover, the shoal 

 known as Peaked hill bar may, as has been suggested, mark the begin- 

 ning of a shore line exterior to that of the present Race point curve. 

 It is possible that as additional tangent spits are lapped on the outside 

 of the curve. Race point will be cut back by a current from the north- 

 west, working opposite to the great current that rounds the peninsula 

 from the east ; a cuspate or acuminate spit being then formed in the 

 angle between the two, such as now exists at Great point, Nantucket. 

 There, the transportation of shore waste is northward on the east 

 shore and southward on the west shore, according to the memoir by 

 Admiral Davife ; this being proved by the drift of coal and bricks 

 from vessels wrecked on the east shore {op. clt., 139). The occur- 

 rence of these '' cuspate forelands," as Gulliver has called them (Bull. 

 Gaol. Soc. Amer., 189G, VII.), is not so much of a rarity in nature 

 as might be imagined from the little that appears about them in books; 

 their growth being sometimes attributable to accordant currents that 

 flow towards the point on either side ; sometimes to opposing currents, 

 one flowinfj inwards, the other outwards. Good reasons iiave been 

 given by Abbe for believing that Cape Hatteras and the other cuspate 

 capes of the Carolina coast have been built between opposing currents 

 (Proc. Bost. Soc. Nat. Hist., 1895, XXVI. 489). 



The Provincetown peninsula may be expected to outlast the Truro 

 mainland ; for as long as the latter exists, the former must receive 

 contributions from it. But when the mainland is washed away, — 

 ten thousand years hence, at the present rate of wearing, — then 

 Provinceland must rapidly disappear. Sable island, a long sand bar 

 oflPNova Scotia, is perhaps to be regarded as the vanishing remnant of 

 a destroyed drift island (see Trans. Roy. Soo. Canada, 1894, XII.pt. 2, 

 pp. 3-48 ; also, note in Science, 1895. 11. 886). It may in this sense 

 be taken to represent a future stage in the destruction of Cape Cod. 

 All these changes are rapid, as changes go on the earth's surface. The 

 Truro mainland will soon be destroj'ed, and the sands of Provinceland 

 will be swept away as the oceanic curtain falls on this little one-act 

 geographical drama. 



