W. A. E. Ussher — Pleistocene Geology of Cormcall 311 



to arrest the inroads of blowing sand, in some cases by collecting 

 hillocks kept together by their matted roots — Ammopliila arenaria 

 (sea reed) ; Triticum junceum (sea wheat grass) ; Hippophce rham- 

 noides (sand thorn) ; Cakile maritima (sea rocket) ; Salsola kali (salt 

 wort); and Sonchus (sand thistle). 



Mr. Henwood (40th Ann. Eep. Eoy. Inst. Corn, for 1858) alludes 

 to the progress of the sand drift covering the low lands of St. Minver, 

 on the east of Padstow, being checked by the growth of Arundo 

 arenaria. 



The appearances of bedding in the blown sands are worthy of 

 note, as they betray the incipient characters which in the old blown 

 sands of Fistral Bay and Greenway have developed on consolidation 

 into marked laminae or thin flaggy sandstones, and near Godrevy 

 and New Quay into thick beds. Although the constant shifting and 

 accumulation of the sands (8 b) upon a growing surface must be true, 

 yet the final entombment and successive growth of grass, or Arundo 

 arenaria, is more likely to have been occasioned by heavy gales 

 drifting large quantities of sand upon the dunes (8 c) ; for, constant 

 shifting of particles would be less likely to produce definite layers ; 

 the cohesion of the particles of successive surfaces of comminuted 

 shell sand lending itself readily to the formation of definite beds, and 

 when counter wind drifts prevailed, to false beds, in the process of 

 consolidation through the downward passage of rain waters. But as 

 far as I am aware no traces of old vegetable surfaces have been 

 found in the old consolidated blown sands. The false-bedded 

 appearance is well shown in the old blown sands of Barnstaple Bay. 

 The thin layers of schorlaceous and quartzose grains in the sand 

 bank at the mouth of the Pentuan Valley seem to be due to marine 

 action, sorting the materials. 



The absence of sand or gravel bars on parts of the Cornish coast 

 directly exposed to the waves of the Atlantic, and their limitation 

 on the southern coast to sites where promontories and headlands 

 shelter them from the direct influence of the prevalent winds, and 

 where the rapid transport of shingle is lessened by projections of the 

 coast on the further side, is worthy of note. Thus, the West Green 

 bank sheltered by the Land's End district occurs in the centre of 

 Mounts Bay ; the Loo Bar, somewhat similarly sheltered, has been 

 piled up where the southerly trend of the Lizard coast-line becomes 

 pronounced ; the Swan Pool Bar and the extensive beaches of Fal- 

 mouth, lying between the flow of the Fal and Helford nearly at 

 right angles, are sheltered in a measure by the Lizard district, and 

 the further transport of shingle is checked by the projection of 

 Pendennis Point. 



The set of the coast-line has been aided by the inability of the 

 stream waters to keep a seaward passage clear, as in the case of the 

 Loo Pool, which represents the ponded drainage of the Cober and its 

 tributaries. The ceremony of cutting the Bar annually to allow the 

 waters to escape more rapidly than by filtration through it, and thus 

 prevent floods, shows how effectually the seaward outlet of the 

 stream has been overcome. The finer accretions to some of the 



