THE PLANTING OF BEACHES
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forester, and must be dealt with by means of groynes and similar constructions.
   It is, of course, perfectly evident from inspection of spontaneously vegetated beaches that Nature alone does not carry through the operation of planting densely or systematically enough to satisfy the requirements here laid down. At the same time Nature carries the matter sufficiently far to indicate clearly what remains to be done. In the preceding sections, the part which vegetation has to play in arresting beach travel has been fully emphasized.
When waves sweep up and a beach is overwhelmed, this is the cumulative result of a series of waves, each of which pares off and transports a thin surface layer (cf. fig. 22, p. 95). The task imposed on vegetation is thus:—
   (1)	To preserve intact the surface layer of the beach, so that
         the shingle shall not get on the move.
   (2)	As plants cannot be relied on to clothe the sea face, the
         vegetation of the crest must have the capacity to catch and hold such shingle as may be thrown up from the front.
   Of native plants, Suceda fruticosa is marked out as the staple for employment. It forms a dense surface mat when pounded by shingle; it has a capacity for rejuvenescence, especially when buried, and it possesses the inestimable advantage of rapid growth. Suseda propagates rapidly from cuttings and by seed. Moreover, in the seedling stage it is tolerant of both shingling over and exposure. In Britain the plant occurs in Wales, on the south coast of England, and along the east coast
 F«6T- 30.—Diagrams illustrating effect on Profile and Land« ward Advance of Planting Crest of Beach with Suaeda
A, The unplanted condition; B, with Suaeda.