CORNISH POST-TERTIARY GEOLOGY. 



35 



BLOWN SANDS AND GRAVEL AND SAND BARS. 



From its more exposed situation the north-western coast-line of 

 Cornwall exhibits by far the most considerable accumulations of 

 blown sand. On either side of the Hayle Estuary, and extending 

 as far north as Godrevy Farm, the lower lands are buried beneath 

 sand dunes. The Perran Sands, in which traces of the ruins of 

 Constantine Chapel are still visible, cover a considerable area, attain- 

 ing in places to more than 300 feet above the sea-level. To the 

 south of Trevose Head the flat land lying on the west of the Camel 

 Estuary is covered by blown sand ; also tlie low-lying tract on the 

 east side of the estuary, in which St. Enodock's Chapel is situated. 

 Blown sand occurs between the latter spot and Tintagel in several 

 places, but of inconsiderable extent. The old consolidated blown 

 sands of the coast near Gwythian and Godrevy, and in Fistral Bay, 

 etc., show that a similar drift of sand prevailed during the Raised 

 Beach formation. A small patch of sand dunes borders Whitesand 

 Bay near the Land's End ; blown sand also caps tolerably high land 

 at Gunwalloe near Mullion, in the Lizard District. 



Mr. Boase ' commented on the absence of documentary evidence, 

 or even popular tradition, of the devastation of considerable tracts of 

 land, and the engulphment of a number of churches by the blown 

 sand : " The particular circumstances of the catastrophe seem to 

 have been already forgotten when Leland visited the place, about 

 300 years ago ; and yet the period of its occurrence could not then 

 have been very remote, because ' the churches ' still extant are 

 evidently not of an age much anterior to that of Leland himself." 

 As, however, this devastation was most probably gradual, no sudden 

 influx of sand worthy of record may have taken place. 



Blown sand sometimes forms the crest of sand or gravel bars on 

 the south-east coast. In the upper part of the West Green Sand- 

 bank, near Marazion Bridge, Mr. Edmonds - discovered numerous 

 land shells to a depth of from 7 to 8 feet from the surface. The 



1 Trans. Roy. Geol. Soc. Corn. vol. ii. p. 141. 



2 Ibid. vol. vi. pp. 303, 304. 



