16 CORNISH POST-TERTIARY GEOLOGY. 



At Pecln-men-du Mr. Carne observed a few boulders at 30 feet 

 above tbe sea. The same observer records the occurrence of a bed 

 of boulders 15 feet tbick, in a disintegrated granite and clay matrix, 

 at 50 feet from tbe surface, and about 500 feet above tbe sea, in 

 sinking a sbaft at Huel Carn tin mine. No boulders were found in 

 tbe lode. 



Mr. Salmon mentioned tbe discovery of granite boulders at 74 

 fathoms from tbe surface in West Eosewarne Mine, Gwinear, which 

 he thought had been introduced by fissures from the surface. 



At Eelistan Mine Mr. Carne mentioned the occurrence of a mass 

 of slate pebbles at 100 fathoms from the surface, but he commented 

 on the presence of spheroidal concretions in the slates in the vicinity^ 



Mr. Whitley ^ gives a sketch section from Zennor Castle to the 

 coast on the north of it, showing boulders of granite on the surface 

 of a bed of decomposed granitic loam, thin on the slope, but as much 

 as 10 feet thick on level ground, and resting alike on granite and 

 killas. Though the above may be due to early Pleistocene denuda- 

 tion, it is more probably ascribable to the period during which the 

 Head was accumulated. Diallage boulders are similarly separated 

 by soil from their parent rock in the Lizard District. 



EAISED BEACHES AND HEAD. 



In the garden of a house by Par Harbour, near Spit Point, I 

 observed gravel (composed of small rounded pebbles of quartzite and 

 granitic rocks, generally of small size, with rounded and subangular 

 boulders) and beds of greenish grey sand (with reddish streaks and 

 fragments of shale), about 6 feet in thickness, and 8 feet above high- 

 water mark at its base. 



On the north side of Spit Point, I obtained the following section : 



Brown sandy soil : gravel of pebbles, principally quartz 4ft. Oin. 



Brown gravel finer than the above : gravel with boulders 3ft. Oin. 



Grey loam with quartz pebbles 1ft. Oin. 



resting on slates at 8 feet above the present beach. 



On the south of Spit Point the base of the gravel is about 10 feet 

 above high-water maik. 



1 Jouru. Eoy. Inst. Corn. Xo. 11, p. 184. 



