602 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



{Hardrensis ?), and Fenestellce ; the sections on both headlands cor- 

 respond with those so well shown at Woodabay, with which they are 

 continuous along* the precipitous north shore under Martinhoe. At 

 Heddon's Mouth the slates strike seaward W. 20° N., and are lost 

 under the waters of the Channel ; thus at several points along the 

 north coast we have the uppermost portion of the Lower or Lynton 

 slates, and their junction with the succeeding red sandstone, well 

 shown, notably so at Woodabay, Valley of Eocks, and Heddon's 

 Mouth ; the cleavage-planes at the latter dip north, at a very high 

 angle ; the fossils occur here, as at Lynton, in definite bands of 

 impure limestone, which weather rusty ; they are difiicult to extract, 

 owing to the indurated nature of the beds. 



The beautiful and deep defile through which the river has cut its 

 way, from Kinacot to the sea at Heddon's Mouth, is composed entirely 

 of the red gritty sandstones of the Hangman, overlying the lower 

 slates before mentioned (see fig. 8, p. 600), which at their upper part 

 unite with the slates of the Middle or llfracombe group near Ead- 

 ley and Middleton Mill. Iron-ore occurs along the junction of 

 these slates and grits at West Challacombe, and is nearly continuous 

 with their strike. In the deep valley of Paracombe we are fairly 

 in the Lower slates of the llfracombe group, which agree in every 

 feature with those containing String oceplialus Burtini and Strepto- 

 rhynclius umbraculum, and which are exposed in the cliffs on the 

 eastern side of Combe Martin Bay, at "West Challacombe, under the 

 Little Hangman. There is no evidence whatever of unconformity 

 along this line between the red grits and the base of the grey 

 Combe Martin or Challacombe slates ; but the change of con- 

 dition would seem to have been accompanied by a submarine out- 

 pouring of igneous matter, the true condition of which requires 

 careful examination and seeking*. The undulating country between 

 Paracombe and Westland Pound, through Lower and Higher Eow- 

 ley, is occupied by the Lower or slaty and calcareous fossiliferous 

 division of the llfracombe series, the rocks of which all dip to the 

 south; and it may be assumed with but little hesitation that a 

 line drawn from Lee Bay to Challacombe (north of Bratton Down) , 

 Eyeson Hill, and Treborough would nearly indicate the marked 

 division that takes place between the lower group of slates, with its 

 associated limestones and well-marked Middle Devonian fauna, and 

 the higher pale-grey glossy unfossiliferous series, accompanied by the 

 quartz veins that form so conspicuous a feature at Lee Bay, Bull Point, 

 Eockham Bay, and Mortehoe, and which unmistakeably strike from 

 the sea on the west to Wiveliscombe on the east, passing north of 

 Bittadon, Arlington, Withypool, Winsford, the ExeYalley, and Exton 

 Hill ; this belt of country in the river- courses and valleys every- 

 where, where I examined it, showed the same physical features. 



* On the south side of the Culm trough, from Padstow to Tintagel and Bro- 

 castle, there are numerous apparently contemporaneously bedded greenstones, 

 and igneous rocks of various composition ; and those of Padstcw &c. may 

 belong to about the same horizon, or be chronologically equivalent with tl)e similar 

 deposits associated with the lower part of the llfracombe group in North Devon. 



