SCHISTS OF THE LIZARD DISTRICT. 5 



From Hot Point to Perranvose Cove the more uniform dark horn- 

 blende schists continue, becoming sometimes more epidotic, sometimes 

 slightly granitoid as we approach the latter. The dips are variable, 

 being in one place W.NWV., with much faulting and other indica- 

 tions of disturbance ; but on the whole the beds appear to strike to- 

 wards the jS".W. with a dip on the eastern side, so that we probably 

 continue to rise in the series. The beds in the cove itself, dark horn- 

 blende schist with marked epidotic and rare quartzo-felspathic bands, 

 have a rather gentle dip somewhat to the south of E.S.E. Dark 

 hornblende schists with epidotic bands continue, so far as can be seen, 

 to the bay, under the Balk Quarry, where we have the first intrusion 

 of serpentine. On reaching the sandy shore we find here, at the 

 southern end of the bay, a decomposed and shattered schist, probably 

 the normal hornblendic rock, capped, in a little reef beneath the 

 quarry, by a well-marked quartzo-felspathic band, which marks the 

 setting in of the uppermost division of the series. 



It may save time to give a brief description of the lithological 

 characters of this group. It is generally rather distinctly stratified, 

 beds of a fairly massive quartzose rock of a purplish-grey colour 

 alternating with darker and more schistose bands. The former 

 varies from a felspathic quartzite, containing occasional flakes of 

 mica or hornblende, to a crystalline quartz-felspar rock, in hand 

 specimens hardly distinguishable from a vein -granite. The darker 

 layers are often rich in mica ; but hornblendic or chloritic minerals 

 are sometimes predominant. Commonly these rocks do not exhibit 

 a very marked foliated structure. Lenticular bedding and even indi- 

 cations of current-bedding are far from rare, and the whole group 

 gives one the idea of having been deposited by rather variable cur- 

 rents in waters of no very great depth. 



The results of microscopic examination will be given below. I 

 have felt much difficulty in giving the group a name, but think that 

 on the whole it ma3 r best be designated as the " Granulitic group," it 

 being understood that garnets are either wanting, or very small and 

 inconspicuous. 



The rocks of this group are well exhibited in the cliffs of the Balk 

 Bay, where, as described in my former paper, they are broken 

 through by serpentine and gabbro, and at low water can be followed 

 for some little distance further north, beyond the " granite-vein," 

 which, as explained in my former paper *, is only one of the grani- 

 toid bands in this group. At a little headland in the bay itself the 

 dip is about 45° N.N.E. The thickness must be considerable, not 

 less than two or three hundred feet and perhaps more ; but the in- 

 terruptions caused by the intrusion of serpentine and gabbro make 

 any estimate most difficult. Beyond this the cliffs are serpentine, 

 and their base cannot be approached ; but after about a quarter of a 

 mile we are able to descend to the shore to Polbarrow Cove, where 

 we find a mass of serpentine intrusive in the granulitic series ; 

 this exhibits close and streaky interbanding of the pinkish-grey and 

 dark varieties. One band of the former, just to the south of a 

 * Quart. Journ. Geol. Soc. vol. xxxiii. p. 894. 



