Vol. 52.] 



ROCKS OF THE LIZAED DISTRICT. 



27 



Pig. 3. — Projection from the 

 granulitic mass included in 

 {East of the Lion 



Rock.) 



/<#■. 



iff 



In all these diagrams the serpentine is 

 dotted, and the fine lines indicate the 

 more micaceous bands in the granu- 

 litic rock. 



shore some little distance to the south, belongs to the granulitic 

 group. The drawing which my friends have given is substantially 

 accurate ' ; the inference also which they draw is correct, but only 

 in an extremely limited sense — in other words, everything turns 

 upon the exact meaning at- 

 tached to the phrase ' solid 

 granulitic rock.' Taking that 

 mass as a whole, its darker 

 bands indicate firstly, the for- 

 mation of a banded or rather a 

 streaky structure, and secondly 

 the contortion of the same 2 ; 

 but, so far as I could see, no 

 connexion exists between these 

 structures as a whole and the 

 external shape of the mass, and 

 there is nothing to difference 

 this block from those which 

 occur, as I have said, to the 

 south and so often on the 

 eastern coast. The rock is 

 only rather curiously con- 

 torted, but this structure is not 



very uncommon in the granulitic group, and I was unable to see 

 that any relation existed between either it or the shape of the 

 mass and the serpentine, or to find evidence either that the granu- 

 litic rock was intrusive in the serpentine or that the two had been 

 folded together, as the result of earth-movements while both were in 

 a. plastic condition. As is stated above, there are two large masses 

 of the granulitic rock on the shore towards the south. These, how- 

 ever, are not wedge-shaped intrusions, but huge blocks ; yet in places 

 they exhibit contortions, which are hardly less pronounced than 

 those in the other mass. 3 The serpentine in their neighbourhood 

 exhibits a slight foliation, which dips at a high angle to a point a 

 little W. of W.N.W., but this neither makes the rock fissile, nor 

 produces any marked effect on its microscopic structure, nor stands 

 in any relation to that of the granulitic masses. 



I accordingly claim a verdict of ' not proven ' here, and pass on 

 to other localities to see how far their evidence is * incompatible 

 with the theory that the serpentine was intruded into solid granu- 

 litic rock.' At the first glance it seems possible to explain the 



1 Op. cit. p. 209, fig. 4. I venture to suggest two trifling emendations. At B 

 the obtuse angle should be replaced by a blunt thumb-like projection (see fig. 3, 

 above), and at D the serpentine occupies the wider, but not the narrower part of 

 the inlet in the granulitic mass : the latter rock being practically continuous at a 

 depth of 3 or 4 inches, as I could see in one place and feel with my fingers all 

 along. To this point I shall return. 



2 These might be either successive stages in one process or separated by 

 gome considerable interval of time (as I incline to think). 



3 In these, however, the ' dioritic ' rock predominates, so that it is granitic 

 (lighter-coloured) bands that wriggle about. 



