360 



TRANSACTIONS OF THE 



[Sess. 



wards and scoops out a hollow in front, to windward of 

 which again may rise a smaller mound of sand or of sand 

 bearing Marram grass (see fig. 1, b and c). Similarly a 

 hollow may be scooped out to leeward of the main hillock 

 (see fig. 1, b and c). Hollows are also formed sometimes 

 at the sides, sometimes with terraces in their outer banks 

 at different levels, presumably due to winds of different 

 force and coming from various directions (see fig. 1, d). 



D. P. et E. S. del. 



Fig. 1 Above : Showing formation of mound with Ammophila arenaria. Link. 



Fig. 2. — Below : Showing shape and mode of advance of Maviston Sandhill. 



A constant feature in connection with the Ammophila 

 is the dark deposit, apparently in the main organic debris 

 from the dead plants, which gathers on the surface of the 

 sand or streams down the slopes, always on the same eastern 

 or leeward side. It is present even at the smallest tuft. 



Although the Marram grass, where it becomes established 

 upon the sides of a long ridge, seems to keep the sand well 

 fixed, yet the isolated mounds referred to have frequently 



