2 34 



[Proc. B.N.F.C, 



Estuary in Cardiganshire, five distinct altitudinal zones of vege- 

 tation can be distinguished. The lower zones are occupied by 

 plants able to endure longer and more frequent submergence in 

 salt water than those living in the higher and drier zones. In 

 many localities the vegetation covering the greater part of the 

 marshes is a compact sward. This affords excellent sheep 

 pasturage, highly valued by farmers not only on account of its 

 feeding properties but also because of its freedom from the liver- 

 fluke parasite. The sward is intersected by numerous natural 

 drainage channels and curious bare drainage hollows known as 

 " pans." The origin and fate of both channels and " pans " was 

 described, and it was shown that, as in the analogous case of sand 

 dunes, there is a constant struggle between the agents of deposi- 

 tion and stabilisation on the one hand, and the agents of erosion 

 and destruction on the other. Tides not only deposit additional 

 sediment but also erode and wear away the edges of the marsh, 

 and scour out and enlarge the "pans." Indeed, large "compound 

 pans " are frequently formed by the coalescence of systems of 

 smaller ones. Sooner or later, however, if the chief river currents 

 and channels remain constant, a kind of balance is struck, the 

 marsh re-forming as rapidly as it is destroyed. It may also be 

 stated that while some of the bare " pans " increase in size by 

 erosion others become filled up and overgrown by vegetation 

 owing to the establishment of natural drainage outlets. By 

 suitable methods of encouraging the deposition of silt and the 

 growth of salt marsh plants upon it, it is possible to so favour the 

 forces of progression (as opposed to those of retrogression) that 

 land reclamation can be effected. This is regularly carried out 

 on a considerable scale in such areas as The Wash of the east 

 of England. 



The lecture was illustrated by a large number of excellent 

 lantern slides from photos, mainly taken by the lecturer, and the 

 lantern was manipulated by Mr. A. R. Hogg. In the discussion 

 which followed the following members took part — The President, 

 Rev. C. H. Waddell, Dr. J. K. Charlesworth, Messrs. J. E. 



