12 



RECLAMATION OF CAPE COD SAND DUNES. 



miglit atford consideralile protection to the vegetation of the sand 

 stretches are blown off and lodged in the lee of the dunes or within 

 areas covered with vegetation. The humidit}" incident to the oceanic 

 location of the Cape acts in favor of the existing vegetation. The 

 average annual rainfall is 42.58 inches. The accompanj^ing table 

 indicates the normal monthly precipitation as compiled from the nor- 



mals for neighboring stations. 



Inches. 



January 3.90 



February 3. 39 



Marcli 3. 98 



April 3. 41 



May 3.62 



June 2. 74 



Inches. 



July 2.89 



August 3.62 



SeptemlxT 2. 91 



October 4. 00 



November 4. 38 



December 3. 74 



The factor of associated vegetation or the interrelations of individ- 

 uals and species is of little importance in areas of shifting sands. The 

 conditions do not admit of a closed formation, that is, where the veg- 

 etation completel}' covers the ground, and it is onl}^ when this does 

 finall}' obtain that the factor assumes an important role in the plant 

 societ3\ 



Mode of Deposition of the Cape Sands. 



The arm of the Cape extending around Cape Cod Ba}^ con.sists of 

 glacial deposits, Avith the exception of about 10 square miles which 

 is composed entirely of post-Glacial sand which has subsequently 

 washed around the head of the Cape from the south, inclosing the 

 harbor within a sickle-shaped .sand hook. 



The addition of sand to the extremity of the Cape apparently takes 

 place in the form of successive bars, which are built up off the north 

 shore and added to the Cape by deposition in the neck of the channels 

 Ij^ing to the east and south, forming successive "race runs" (PI. 1), 

 which are graduall}' filled in b}^ tide and wind deposits. The sand 

 cast up by the waves on one of these new beaches is dried and blown 

 inland, forming a beach ridge orforedune and eventualh^adune range, 

 which, protected by the succeeding deposits, ultimately becomes cov- 

 ered by the forest and associated vegetation. 



The above h^-pothesis is supported by the following observed facts: 

 (1) Four old dune ranges now forested but badly distorted by the 

 long-continued action of the wind; (2) three dune ranges held only by 

 beach grass and hing north of the first-mentioned ranges, parallel with 

 them and also with the north shore of the Cape; (3) a race run (now 

 nearl}'^ filled in) with its flanking beach ridge fast becoming a conspic- 

 uous foredune (PI. 1 and PI. II, fig. 1); (4) a bar in present process 

 of formation offshore and to northward of the present shore line but 

 parallel with it; (5) the seven dune ranges indicated constitute the 



