Research: Forvie Sands

Knife edge dunes

Original text

Waves 2 & 3 fixed by vegetation on their leeward side, unlike the wandering dune, are in various stages of erosion by wind on their windward, this slope reaching an angle of 32 deg. at the base, even greater at the crest where undercutting of crest vegetation occurs. There is little forward movement here, a mere dusting of sand being blown forward. Consequently more closed grass communities, even heath may be found on the leeward. Fig. 4 shows erosion of the windward face; tufts of Ammophil (Marram) are seen slipping down it. Note bow shape of this face, enclosing hollow at water level

Figure 4.

Wind ----->

Erosion stage in profile

The remaining two of four examples of knife edge dunes seen from above. Movement from a to b. From Forvie.