370 TRANSACTIONS OF THE [Sess. lxxix. 



denuded. A tree of Alnus rotundifolia breaks the barren 

 stretch of rather level sand near the rear base of the chief 

 dune ; the lower part of this tree has become exposed by 

 the removal of sand which had previously blown over the 

 roots and lower trunk. 



The dune is moving uninterruptedly into the great pine 

 forest which was planted to confine the area of sandhills. 1 

 Every year more trees are engulfed from the wood's margin 

 for the time being. For the original edge has long ago 

 disappeared. The trees which have already been drowned 

 by the wave of sand reappear on its rear slope as the 

 ridge advances, and all that slope is dotted with the black 

 trunks of ruined pines. Some stand erect at the foot of 

 the hill, but are like paper in consistency ; a pull suffices to 

 topple over the trunk, perhaps ten feet high and a foot 

 or more in diameter. Higher up the slope more and 

 more of the bole is covered. No fungi or other plants 

 grow on the slope. Fig. 2, a and b, suggests the form and 

 mode of advance of the dune. 



On the plateau-like summit branches appear as if lying 

 unattached in the surface sand ; they are really attached 

 to trees standing hidden in the dune. Tops also appear 

 with branches bearing withered leaves, even cones. Tufts 

 of Ammophila arenaria grow here and there beside these 

 projecting branches — the only truly living flora of the dune. 



On the landward slope the process of engulfing is seen 

 actually going on, as shown in the accompanying photo- 

 graph (Plate LVII). This slope is steep, the form of the 

 dune being a reversed crag-and-tail. Branches project, or 

 nearly whole trees, according to the position on the slope 

 and the position of the trees with reference to the line of the 

 dune's advance into the wood. Even in those pines, well 

 buried near the crest of the dune, the leaves are still fresh 

 and green, and numbers bear still unopened cones, even 

 cones of the current year. 



On the floor of the wood the loose sand extends for a 

 short distance beyond the clearly marked base of the 

 straight front slope. On this new soil grow Carex arenaria 

 and Juncus squarrosus, like an advance-guard of the 

 invasion of the forest. 



1 Bain, The River Findhorn, pp. 241-242. 



