THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE II. VOL. V. 



No. v.— MAY, 1878. 



(D:RXG-XJ<r.A.Xj ^^laTICXilBS. 



I. — Notes on the Devonians and Old Eed Sandstone of Noeth 

 AND South Devon. 



By A. Champernowne, M.A., F.G.S. 



(PLATES V. AND VI.) 



IT may seem to many geologists, accustomed to speak of the 

 " simple order of North Devon," a somewhat unusual process 

 to fall back on the more troubled districts of the southern division 

 of the County for evidence upon which to take one's stand in 

 interpreting the grand facts of succession within the original 

 " Devonian " area, Devonshire. That is, however, the plan of 

 campaign which I shall adopt ; but instead of publishing the 

 paper I read last year before the British Association, in Section C, at 

 Plymouth (which will appear in abstract in the Annual volume of 

 Eeports), I will only recapitulate the facts I then brought forward, 

 relating to the southern limestones of Torbay. 



In doing so, my chief reason is that I have heard the value of 

 that evidence denied, and the original reading of the section strictly 

 adhered to. 



In the two diagrams on Plate YI. Figs. 1 and 2, (1) represents the 

 limestone of Berry Head, and the flap of the same south of Mudstone 

 Bay; (2) the slates of Mudstone Bay; (2*) the slaty rocks of a 

 slightly different aspect south of the limestones; (3) red sandstones 

 corresponding to those of Staddon Heights and Mount Edgecumbe ; 

 (4) intrusive trap altering the rocks at the contact ; (cf ) hasmatite 

 iron-ore deposited in the hollows of the limestone, and not a bed, 

 as sometimes represented. 



It will be observed that (1*^') is a trough of the limestone beds, 

 the bottom of which is clearly seen; close beyond it unites with 

 the main mass. The right-hand tongue of trap forms the extreme 

 headland of Sharkham Point, the limestone adjoining it on the 

 right being nearly vertical, whereas it sets on at the southern end of 

 Mudstone Beach at an angle not greater than 45°. 



Now I contend that in the minor trough which we can see, we are 

 furnished with a direct clue to the structure of the main mass, the 

 bottom of which is not seen, but is at some depth below the sea. 

 I believe that such dotted lines as those in diagram (1) are 

 natural, but that those of diagram (2) are scarcely conceivable. 

 The minor trough cannot be ignored, and I cannot imagine it 

 possible that a portion of the slates (2*) can have been introduced 



DECADE II. YOL. V.— NO. V. 13 



