OF THE SOUTH DEVON COAST. All 
of heat, pressure, and alkaline water on these slaty rocks of Torcross 
had been sufficiently prolonged, we can hardly doubt that the darker 
laminz would have been converted into bands of mica, the greyer 
streaks into lenticular aggregates of quartz and felspar. All trace 
of the original bedding might thus have been lost, and the presump- 
tion from the general aspect of the foliation would have been that 
the original stratification had been parallel to it. Certain portions 
also of the rock would have closely resembled an augen-gneiss. 
In offering these suggestions, I wish to guard myself against 
being supposed to put forward a general theory of foliated rocks. 
I merely mention these as a possible explanation of certain cases of 
foliation, and certain cases of “eyed” structure. Iam only pre- 
pared to make one general induction, namely, that a lenticular struc- 
ture in a foliated rock is probably an indication that it has been 
subjected to pressure in a definite direction, which, though making 
a fairly large angle with, is not at right angles to, the dominant 
mineral banding. From what I have seen of foliated rocks in a 
rather wide experience, I am convinced that very commonly their 
characteristic structure, speaking in general terms, is parallel with 
the original stratification, and that there are many augen-gneisses 
to which the above explanation does not seem to be applicable *. 
8. Conclusions as to the Relations of the various itocks in the above 
District. 
From the foregoing remarks it is evident that in this district of 
South Devon two questions especially present themselves for con- 
sideration :—one, the relation of the foliated to the slaty series, the 
other, the mutual relation of the members of the former series. As 
regards the former question, we have to decide whether we find in 
the sections above described—a case of progressive metamorphism, 
so that we pass in descending order, from true slates to true schists— 
or two distinct groups, of which the lower was probably metamor- 
phosed before the upper was deposited. 
The facts mentioned above in detail prove, I think, that there is 
no valid evidence of a passage from schist to slate. While I can- 
not assert that there is a conspicuous fault, as in the Lizard districty, 
yet the transition from the one class of rock to the other is so abrupt 
as to be incompatible with the idea of progressive metamorphism, 
while at Hope Cove and to the north of Salcombe the chloritic 
schist appears to approach much nearer to the slaty series than at the 
Start; but apart from the former of these considerations—that we 
pass from slates and phyllites (to use the strongest term that can be 
applied to them), from rocks in which the metamorphism can at 
most be called incipient, to true schists, too rapidly for us to regard 
* JT may refer in connexion with this subject to a paper read before our 
Society by the late Mr. G. Poulett Scrope on May 12, 1858, and published, 
with an admirable illustration, in the ‘Geologist’ for 1858, p- 361; a paper 
replete with valuable suggestions, which, as it appears to me, has not attracted 
the notice which it deserves. 
t Quart. Journ. Geol. Soc. vol. xxxix. p. 1, 
