54^ RECENT. 



tliey nevertheless represented two distinct civilizations.^ Other caverns occur at 

 Chudleigh, Newton Abbot, etc.^ 



At Yealmpton, not far from Yealm Bridge, near Plymouth, a Cavern in the 

 Devonian Limestone was explored in 1832 by Mr. J. C. Bellamy. Remains of 

 Elephant, Rhinoceros, Hyrena, Bear, and (jlutton have been found. ^ Other caves 

 at Oreston were discovered by Mr. Wliidbey (1816-22) ; and these caves were the 

 first systematically explored in this country. 



Fissures containing bones are not unfrequently met with, as at Bath and at 

 Portland, in the Oolitic limestones. 



That Cave-deposits of Pliocene and earlier periods have not been discovered is 

 due perhaps to the fact that no Caverns of such antiquity have escaped denudation. 



Blown Sands. 



On coasts where a great quantity of sand is accumulated, and 

 where the land is comparatively flat, hillocks or 'dunes' of sand 

 are raised along the shore, and the ground for some distance inland 

 is coated with a sandy soil. These hillocks are caused by the wind 

 blowing away the sand exposed at low tide ; hence the deposits are 

 sometimes known as yEolian Drift. Very often the beds of Blown 

 Sand contain marine as well as common land shells, or fragments 

 of shells, as on the hill above Sennen Cove, overlooking Whitesand 

 Bay (Land's End), and on the Warren at the mouth of the river Exe. 

 Wind 'ripple marks' are sometimes met with. 



Sand-dunes rise to heights of 40 or 50, and rarely to upwards 

 of 80 feet ; but the slope is never more than 30°.^ They are 

 frequently protected by the INIarram grass, Psamma {Anaido) 

 arenaria . 



In Cornwall, Blown Sand occurs at Lelant, Phillack, and Gwythian Towans, 

 in St. Ives Bay, at Perran north-east of St. Agnes Plead, and at Constantine Bay, 

 near Falmouth.'^ On the north coast of Cornwall a considerable tract of cultivated 

 land has been overwhelmed by Blown Sand. The church of St. Piran, in Perran- 

 zabulo (or Perran in Sabulo), was at one time smothered in sand ; but through the 

 shifting of this covering, the church was partially exposed in 1870. Gwythian 

 church was also smothered. The sand is largely composed of comminuted sea- 

 shells, and Mr. Richard Edmonds has obtained at Phillack Towans many speci- 

 mens of land-shells. In places the sand has become sufficiently indurated (partly 

 by oxide of iron) to be of use for building-purposes.'' 



The formation of sandstone is instructively illustrated by recently-consolidated 

 sand at Newquay in Cornwall, and many similar examples exist around our 

 western coasts, where hills of Blown Sand prevail. The water percolating 



^ Pengelly, Trans. Devon Assoc. 1 868-1 884 : G. Mag. 1867, p. 430; 

 MacEnery, Cavern Researches, edited by E. Vivian, 1S59. Mr. MacEnery's 

 collection is now in the British Museum. 



- Pengelly, Trans. Devon Assoc, vi. 46. 



^ Col. Mudge, Proc. G. S. ii. 399. 



* Topley, Pop. Science Review, xiv. 133. 



* Towan (towyn) means Dozuiis or Sand Hills ; Les Landes, or 'barren heaths,' 

 form a sandy district on the south-west coast of France, hence Lelant, Edmonds, 

 Trans. Plymouth Inst. iii. 22 ; Ussher, Post-Tertiary Geol. Cornwall, p. 35. 



® H. Boase, Trans. R.G.S. Cornwall, ii. 140. 



