54 W. MW. Hutchings—Altered Igneous Rocks, Tintagel. 
the more northern part of the coast have not received a similar 
amount of attention. 
Referring to the map of the Geological Suitey of the district, we 
find no occurrences of “Greenstone” marked along the coast, or its 
immediate vicinity, from the neighbourhood of Port Isaac to that of 
Tintagel, where several outcrops are indicated, extending along to 
near Boscastle, where we pass from the Devonian to the Carboni- 
ferous rocks. There are, however, other prominent occurrences of 
greenstone around Tintagel which are not shown on the map, 
notably the very extensive exposure at Trebarwith Strand which is 
alluded to by De la Beche in his “‘ Report of the Geology of Corn- 
wall, Devon, and West Somerset” (1839). 
In this report there are several references to the igneous rocks 
of this special strip of the coast. Thus, on pp. 56 and 57, Beche 
speaks of ‘“‘schistose beds” which are intermingled with the “slates 
and grits which emerge from beneath the Carboniferous system,” 
and describes these schistose rocks as “strongly reminding us of 
the substance of greenstone, finely comminuted and permitted to 
settle in water in which calcareous matter was occasionally present.” 
He states that “ greenstones, some large-grained, occur near Tintagel, 
and the trappean schistose rock is also discovered mingled with 
them, particularly towards Bossiney.” 
He looks on the “ schistose trappean rock” as an altered ash, and 
considers that the two kinds, compact and schistose, have “ probably 
been erupted, one in the state of igneous fusion, and the other in 
that of ash, during the time that the mud now forming slates was 
deposited.” 
This sharp distinction made by Beche between the compact and 
schistose rocks of this neighbourhood, and the definite inference he 
draws as to their different conditions of origin, would not now, with 
modern methods of examination, hold good in all cases. Passages 
of his “large-grained” or ‘‘compact” greenstone into the most 
highly schistose rock may be observed which leave no doubt that 
the original material was one and the same for both. 
There are other occurrences of schistose rock whose origin we 
may safely say was igneous, but concerning which, in their present 
extremely altered condition, we could not arrive at any safe con- 
clusion as to whether they have been derived from massive or 
fragmental material. 
The occurrence which I will first notice is seen in the cliff at the 
side of a cove which is not named on the map, and of which I heard 
no name on the spot. It is the next little inlet sonth of Bossiney 
Cove, separated from it only by the neck of land off which lie the 
rocks called “The Sisters.” The exposure in question is at the 
south side of this nameless cove. There is an outcrop, at the surface 
above the cliff, of angular craggy blocks, and the continuation may 
be seen dipping steeply down towards the sea. At the outcrop the 
rock is coarse-grained and massive, showing no foliation at all. It 
is very hard ane tough, making excellent road-metal, for which 
purpose it is taken in quantity ‘from a similar outcrop in a field a 
