2 PROF. T. G. BONNEY ON THE GEOLOGY 
this district is described in the paper of Sedgwick and Murchison 
“Qn the Stratified Deposits of Devonshire” (Trans. Geol. Soc. 
ser. ll. vol. v. p. 633), and in the “* Report” of Sir H. De la Beche. 
In these two works, which after the lapse of more than forty years 
are still of the greatest value, the stratigraphy of South Devon is 
excellently sketched, and the main problems relating to it are 
clearly enunciated. Briefly stated, the latter amount to this: Does 
this district indicate a progressive metamorphic action, which in- 
creases in intensity as we proceed southwards ? or do we find here 
two distinct and independent series, the southern, a group of highly 
metamorphosed rocks, true schists, the northern, slates, such as are 
common elsewhere in Devonshire, with no signs of a transition 
from the one to the other? Sedgwick and Murchison, if I under- 
stand them rightly, incline to the latter view; Sir Henry De la 
Beche inclines, though hesitatingly, to the former, which appears 
generally to have found favour with later writers, including Mr. 
Pengelly himself *. Accordingly the schists of the southern part of 
this district are regarded simply as altered Paleozoic rocks, possibly 
of Devonian age, whose upheaval is connected with the series of 
Fig. 1.—Sketch-map of the South Devon Coast from Toreross to 
Hope Cove. (Scale about 3 miles to 1 inch.) 
THURLESTONE ¢—— 
RUCK = 
e SOUTHPOOL = 
@_._- Sesas 2SSe555= : 
& 
Se as a a pe om oe 
— GHIVELSTONE 
E297) NN PORTLEMOUTH : 
WT PRAWLE 
. 
lt MEW STONE 
BOLT HEAD 
PRAWLE PT 
Aste Nevies A A. Bands of Mica-schist interstratified with 
= 5 Shc ae ag lower parts of Chloritic schist. 
6. Mica-schist. aa. Boundary in the Survey Map. 
ce. Chloritic schist. B. Axis of Chloritic schist. 
post-Carboniferous disturbances which have affected the south-west 
of England, and whose metamerphism is probably due to some 
proximate protrusions of igneous rock, analogous to those yet visible 
* This opinion is also adopted, with some hesitation, by Dr. H. B. Holl, in 
his invaluable paper “On the Older Rocks of S. Devon and Cornwall,” ” Quart 
Journ. Geol. Soc. vol. xxiv. p. 400. 
