Geological Society. 455 
In gun-fire experiments the pitch of the explosion is not 
known, and there may therefore be a variation in the recorded 
velocities which is due simply to an effect of conical or 
spherical divergence. If, in addition to the corrections made 
by Le Eoux for temperature, some of the gun-fire experiments 
were submitted to a correction of this nature, the discrepancies 
would probably be much reduced. 
LXVI. Proceedings of Learned Societies. 
GEOLOGICAL SOCIETY. 
[Continued from p. 240.] 
November 7, 1883.— J. W. Hulke, Esq., E.B.S., President, 
in the Chair. 
THE following communications were read : — 
1. " On the Geology of the South Devon Coast from Tor Cross 
to Hope Cove." By Prof. T. G. Bonney, M.A., P.B.S., Sec. G.S. 
The author, after a brief reference to the literature of the subject, 
stated that the chief petrographical problem presented by this 
district was whether it afforded an example of a gradual transition 
from slaty to foliated rocks, or whether the two groups were per- 
fectly distinct. He described the coast from Tor Cross round by 
the Start Point to Prawle Point, and thence for some distance up 
the estuary leading to Kingsbridge. Commencing again to the north 
of Salcombe, on the other shore of this inlet, he described the coast 
round by the Bolt Head and Bolt Tail to Hope Cove. These rocks, 
admittedly metamorphic, consist of a rather thick mass of a dark 
mica-schist and of a somewhat variable chloritic schist, which also 
contains a good deal of epidote. In the lower part of this are some 
bands of a mica-schist not materially different from the upper mass. 
It is possible that there are two tbick masses of mica-schist, one 
above and one below the chloritic schist ; but, for reasons given, he 
inclined to the view that there was only one important mass, re- 
peated by very sharp foldings. 
The junction between the admittedly metamorphic group and the 
slaty series at Hope Cove, as well as that north of Salcombe, is clearly 
a fault, and the rocks on either side of it differ materially. Between the 
Start and Tor Cross the author believes there is also a fault, running 
down a valley, and so concealed. On the north side of this the rocks, 
though greatly contorted and exhibiting such alterations as are usual 
in greatly compressed rocks, cannot properly be called foliated, while 
on the south side all are foliated. This division he places near 
Hallsands, about | mile to the south of where it is laid down on the 
geological map. 
As a further proof of the distinctness of the two series, the author 
pointed out that there were clear indications that the foliated series 
