GEOLOGY 



The sections of the Carnon stream works in the valley which opens 

 from the head of Restronguet Creek, as described by Mr. Edward Smith 

 in 1817, and by Mr. Henwood some twenty-five years later, confirm the 

 evidence at Pentuan of the burial of forest growths beneath the level of 

 the sea. Moreover both these observers record the occurrence of human 

 skulls, together with animal remains, principally of the deer, at a depth 

 of over 50 feet beneath the surface. Sir Henry De la Beche mentions 

 also that ' at Pentuan human skulls are stated to have been found under 

 about 40 feet of detrital accumulations, also mingled with the remains of 

 deer, oxen, hogs and whales.' 



Assuming therefore that the forest bed noted at Pentuan 52^ feet 

 below the surface corresponds to the similar deposit at Carnon, with 

 human skulls 53 feet beneath the surface, then, as Sir H. De la Beche 

 has pointed out, ' a considerable change took place in the relative levels 

 of sea and land since man inhabited Cornwall, allowing estuary or 

 marine deposits to be effected in creeks upon a surface that previously 

 permitted the growth of terrestrial vegetation, the remains of the marine 

 creatures entombed in the mud, silt, or sand, showing that these creatures 

 were of the same species as those which now exist in the adjoining sea.' 



The ancient beaches which fringe the Cornish coast were laid down 

 in the Pleistocene seas, and now form ledges extending from only a few 

 feet above the present sea level to a height of 65 feet. A beach at the 

 latter elevation, according to Mr. Clement Reid, ' the highest raised 

 beach yet discovered in Cornwall,' is seen in Penlee quarry, near Newlyn, 

 where coarse beach-shingle rests on a rocky shelf 65 feet above ordnance 

 datum. The old cliff and beach can be traced at about this level through 

 Penzance, and sweeping round Mounts Bay behind the marshes.' Among 

 the more noteworthy of these beaches are those which occur near 

 Newquay and Godrevy, at St. Ives, Cape Cornwall, Coverack Cove, 

 Falmouth Bay and Gerrans Bay. So long ago as 1758 Borlase de- 

 scribed the deposit south of Cape Cornwall, although it is not actually 

 certain that he grasped its significance to the extent of recognizing 

 it as an ancient beach. In 1828 Mr. Carne indicated their occurrence 

 at various localities along the cliffs of western Cornwall. In 1832 Mr. 

 R. W. Fox, F.R.S., described the raised beaches of Falmouth Bay, as 

 forming a bed of rounded quartz pebbles, gravel and sand, resembling that 

 of the present coast, and from 9 to 1 2 feet above high water mark. 1 In 

 the same year their frequent occurrence along the Cornish coast was 

 noticed by Dr. Boase, who considered that in maximum height they did 

 not exceed 50 feet above sea level, and sloped from that point beneath 

 the sea just as our present shore does. ' Thus also,' he observes, ' the 

 beds of gravel and sand at Fistral and Gerrans Bay, and elsewhere, 

 exhibit the same phenomena, the lower part of these sometimes 

 touching the waves, and at others appearing on the cliffs resting on 

 the rock far above the present sea-level.' 3 



These raised beaches, composed of material identical with that of 



1 Trout. Geol. Soc. of Cornwall, iv. 468. * Phil. Mag. and Journal of Science, Dec. 1832. 



