Conglomerates, and Marls of Devonshire. 
89 
opinions have been divided as to whether the Red rocks south of the 
Exe are Permian or Lower Trias ; the latter has been the preva- 
lent idea, and the rocks are coloured in accordance with it in the 
JVIaps of the Geological Survey. I endeavoured in the paper just 
mentioned^- to prove that they are not Permian, and unquestion- 
ingly accepted the other alternative. My second paper contains 
■what still appears to be good evidence that the rocks on the op- 
posite sides of the estuary of the Exe belong to one and the same 
series f ; and, consistently with the premises, it was inferred that 
the whole are of the age of the Bunter. I was not then acquainted 
with the antagonistic facts presented by the rocks in the extreme 
east of the section. The present position of the argument is as 
follows : — 
1. The rocks in the southern part of the section cannot be 
older, but there is nothing to show that they are not more modern, 
than the Bunter, 
2. Their colours and petralogy show that they form one unin" 
terrupted series with those in the eastern part of the area ; and 
the lithology of the two is not incompatible with this. 
3. The eastern beds unquestionably belong to the age of the 
Keuper ; to which therefore the entire series must be referred. 
To those who accept the premises, the inference which I have 
drawn must be inevitable. 
On looking back from Charton Bay along the forty miles of 
Triassic coast, it is impossible not to reflect on the enormous 
volume of the formation, and the vast period of time which it 
represents. 
Assuming that when deposited all strata were horizontal, and 
that no important faults occur amongst them, it is obvious that the 
thickness of a series of inclined beds will be obtained by multi- 
plying the sine of their angle of inclination by their horizontal 
extension in the direction in which they dip. For let (in Fig. 1) 
* " Transactions," 1861-2, pages 27-29. 
t " Transactions," 1862-3, papjes 35, 36, 
