121 



coast between Laiidewednack and Kennack Cove, more particularly under 

 the Balk, near Laiidewednack, and at the remarkable cavern and open cavity 



named the Frying Pan, near Cadgwith In contradiction to 



this apparent passage we find a mass of serpentine amid the hornblende 

 slate, between Dranna Point and Porthalla, on the north of the principal 

 mass of serpentine which has every appearance of having been thrust up 

 among the hornblende slate, twisting and contorting the laminae adjoining 

 it in directions which we should consider consistent with the passage of the 

 serpentine in a state of igneous fusion through them." 



Professor BONNEY has studied the relations of the serpentine to the 

 hornblende-schists and arrived at conclusions different from those expressed 

 in the above quotation. Many of the junctions, referred to by DE LA BECHE 

 as indicating a passage from hornblende- schist to serpentine, he regards as 

 conclusive in favour of the view that the mother rock of the serpentine was 

 intrusive. Thus, at Pentreath Beach, west of Lizard Town, the serpentine is 

 held to be intrusive, and fragments of the hornblende schist are mentioned as 

 occurring in it. At George's Cove " tongues of serpentine are thrust into 

 the schist within a foot or two of the junction." Hornblende- schists " with 

 intrusive tongues of serpentine occur near Perranvose on the east coast near 

 Laiidewednack." At the Balk, also near Landewednack, saussuritic and 

 actinolitic gabbro occur in association with the serpentine ; and the latter 

 rock is seen, according to Professor BONNEY, to be intrusive, in ihe schist 

 and in the serpentine. At the Devil's Frying Pan, near Cadgwith, " the 

 relations of the serpentine with the schist, as seen by descending into this 

 hollow, leave no doubt that the former rock is intrusive." At Coverack Cove 

 the serpentine is seen in relation with troctolite (older gabbro of Professor 

 BONNEY'S first paper) and gabbro. The latter is a part of the great mass of 

 Crousa Down which forms the coast line between Coverack Cove and 

 Manacle Point, a distance of two miles. 



In addition to the rocks above mentioned dykes of granite occur on the 

 west coast, and dykes of " greenstone " (epidiorite) on the east. 



If we examine the descriptions given by Professor BONNEY of the field 

 relations and microscopic characters of the gabbros, and still more if we 

 examine the rocks themselves in the light of the researches of LOSSEN in the 

 Hartz and LEHMANN in Saxony, it is impossible to avoid the conclusion that 

 the Lizard peninsula has been profoundly affected, and probably at 

 more than one period, by regional metamorphism. It must be remembered 

 that Devon and Cornwall form a part of the great Hercynian chain of northern 

 Europe ; that they contain the same rocks and have been affected at the same 

 periods by the same earth-movements. The effects of regional metamorphism 

 on the basic igneous rocks of Devon and Cornwall, which were formed before 

 the great earth-movements took place, will be described later on ; at present 

 the subject is only referred to because it serves to suggest that the 

 discrepancies, between different observers, as to the field relations of the 

 serpentine may possibly arise from complications due to the later earth- 

 movements. 



Many varieties of serpentine depending on variations in the mineralogical 



