ETHEEIDGE — DEVONIAN EOCKS AND FOSSILS. 



591 



limestones of Pixton Park, Coombe, and Clayford being of the same 

 age as the dark-grey limestone and brown sandstone series of Sloly 

 and Marwood, which weather rusty, and then exhibit their fossil 

 contents in the form of casts and moulds. At Combe, Strophalosia 

 productoides and casts of Petraia and Rliynclionella ^leurodon were 

 observed. 



The succession fi'om the red grits and Lower sandstone of Tim- 

 berscombe and Bickham, through the succeeding Middle sandstone 

 and slates at Oaktrow and Cutcombe, with their associated coral- 

 limestones at Wheddon Cross, and the succeeding mass of undulating 

 Morte slates, to the base of the Upper Old Red Sandstones of Dul- 

 verton Down, is complete and continuous ; neither is there any sign 

 of unconformity between this sandstone band and the underlying 

 slates ; they constitute one complete and continuous series, with no 

 break in the succession up to the Brushford beds on the south, 

 where, both on physical and palaeontological grounds, a marked 

 change takes place, and we are fairly at the base of the Carboniferous 

 (carbomiceous) series. 



7. Didverton to Wiveliscomhe. — Immediately to the south of Had- 

 donDown, atHele,Eord,Upcots, Beckham, &c., the upper beds of the 

 Upper Old Red Sandstone are visible in many places ; they are red 

 and chocolate-coloured, thin-bedded, slaty, micaceous, earthy sand- 

 stones, passing insensibly into the slates of the Baggy group ; in 

 the valley half a mile south-east of Upcots, they are well exposed 

 in a quarry, as well as in natural sections, and dip south 45°. 



The structure of Haddon Down is precisely the same as that of 

 Dulverton Down and Hawkridge Common and aU the range to the 

 west ; and traverses made on the route to Wivehscombe, over Haddon 

 and Heydon Downs, showed the same conditions ; and the deep gorge 

 of the river at Challick Earm, south of and under Main Down, and 

 at Chipstable, proved the conditions to be the same as at Dulverton, 

 the strike of the sandstone and slates and the conformity being evident 

 from west to east (from Dulverton to AViveliscombe). My attention 

 here was chiefly confined to the northern side of Main and Heydon 

 Downs, extending from the Oakhampton slate-quarries along the 

 line of fault in Langley Marsh to Huish Champflower, Raddon, 

 and Washbattle Mills, &c. 



This point was selected as being the only place where a fault had 

 been laid down by Sir H. De la Beche along the line of country 

 which has been assigned to the supposed great east and west fault, 

 having a downthrow to the north, and thus causing that ideal 

 inversion of the rock-masses of North Devon which has been said to 

 have placed the great band of S'andstone striking from Pickwell Down 

 to Main Down, Wiveliscomhe, and the Quantocks, below the under- 

 lying Lower Devonian sandstones, grits, and slates of Lynton, 

 placing the Foreland and Ljmton group on the same horizon as that 

 of Baggy and Marwood, &c. Li other words, this fault admitted to 

 the extent required, and according to the views advocated, tlie whole 

 of the intervening slates and limestones of the Ilfracombe group and 

 their underlying Hangman grits and sandstones, with the entire 



