446 IF. A. E. ZTssher — Palceozoic Rocks of Devon and Somerset. 



The boundary between the Middle Devonian slates and the Pick- 

 well Down beds has been carefully traced by me throughout the 

 area, with the exception of five miles between West Down and 

 Loxhore, on either side of Bittadon. Near Woolacombe northerly 

 dips in the Middle Devonian (Morte slates) would give colour to Prof. 

 Jukes's supposition of a fault ; but they are speedily counteracted, 

 and can only be taken to indicate a local roll or inversion in the 

 beds near their junction which follows the contour. The junction 

 through Smitha Park near Loxhore, is effected by a fault running 

 north-west and south-east for two miles and is probably also a fault 

 where it crosses the Bray Valley near Office Farm. From the coast to 

 Span Plead the Pickwell Down beds do not appear to pass lithologically 

 into the Middle Devonian ; but from Span Head eastward purple 

 slates make their appearance at the base of the Upper Devonian, and 

 form a perfect passage into the slates of the underlying series (see 

 Proc. Somerset Archseol. and Nat. Hist. Soc. for 1879, part ii. " On 

 the Geology of Parts of Devon and West Somerset north of South 

 Molton, etc.," where the nature of the Middle Devonian slate series 

 and its junction with the Upper Devonian between Challacombe and 

 Lype Hill has been described in detail). 



The j unction extends by Withypool and Exton Hill to Blagdon 

 Hill, whence, through an anticlinal structure, in part complicated by 

 faults, the Middle Devonian slates extend westward through Brompton 

 Eegis to beyond Browford Farm ; proving that the great superficial 

 breadth of the Pickwell series between Dulverton Common and 

 Landacre Bridge (near Withypool) is due to flexures. The junction 

 recrosses the Exe and runs along the north flanks of Haddon Down, 

 Heydon Down, and Main Down Hills, finally disappearing under 

 the Triassic rocks on the north of Wiveliscombe. 



Morte Slates. — The upper part of the Middle Devonian slate series 

 consists of greenish grey glossy slates, unfossiliferous, and containing 

 much quartz ; but in the Brendon Hill area these characters are not 

 persistent, the slates exhibiting bluish grey and silvery hues, and 

 being frequently irregular and gritty. 



Ilfracombe Beds. — The lower part of the series is much less 

 homogeneous, being composed of slates and shales with films of 

 arenaceous material and irregular impersistent beds of limestone. 

 The arenaceous element is strongly developed in the Quantock area 

 near Enmore and Asholt, where grits are so abundant as to occasion 

 some difficulty in distinguishing the base of the series from the 

 Hangman division. Grits also occur on the east of Croydon Hill 

 and near Cutcombe. 



Limestone bands are most numerous in the vicinity of Combe 

 Martin, and on the Quantocks. Where the calcareous matter was 

 distributed in thin strings or patches, it has frequently been entirely 

 dissolved away, leaving a friable sandstone residuum. 



Upper Devonian. — The Pickwell Down series occupies a superficies 

 of about 85 square miles. It is composed of an upper portion of 

 Indian-red-coloured slates upon red, green, and grey grits ; the lower 

 beds appear to be greenish and brownish grits, between the coast 



