618 DR. G. J. HTNDE AND ME. HOWABD POX ON [NOV. 1 89 5, 



character to those of Codden Hill, and, like them, are filled with 

 radiolaria associated with sponge-spicules. At Templeton and at 

 a quarry west of Corffe Lodge, the beds dip north and south on 

 either side of an anticlinal fold of 60°. At Tawstock Quarry also 

 there are thin beds of the light, porous, yellow rock with casts of 

 trilobites and crinoid-stems resembling those at Hannaford. 



An outlier of radiolarian rock is exposed at the top of a ridge 

 about a mile due north of Codden Hill itself, in a small quarry near 

 Venn Cross, about one mile S.E. of Barnstaple. The beds here are 

 for the most part hard, and either dark or light grey. They dip 

 S. 15° E. at 45°. In the valley between this Venn Cross ridge and 

 that of Codden Hill are situated the noted Venn quarries of dark 

 limestones and shales, which are now disused and filled with 

 water. 



Thus on either side of Codden Hill, from Templeton on the west 

 side of the Taw River to the High Down at Heddon, a distance of 

 about 7 miles in an approximately east-and-west line, there are 

 frequent exposures of the radiolarian rocks. 



(b) Dulverton,, West Somerset. 



Eastward of Heddon the next outcrops of radiolarian rocks which 

 we have examined are situated near Dulverton Station, about 

 17 miles distant. In this neighbourhood there are three impor- 

 tant quarries : the most westerly is at Kent's Hill, a prominent 

 conical hill about 5 mile due south of Brushford village. The 

 beds in this quarry are nearly uniformly of hard, dark, platy, 

 siliceous rock, weathering to a slaty grey, without any admixture of 

 soft shales. Only one thin band of the light-grey rock was noticed, 

 which was filled with radiolarian casts. In the dark platy rock the 

 radiolaria can be seldom distinguished, unless in microscopic sections ; 

 they are generally associated with sponge-spicules. The beds in 

 this quarry are much less jointed than usual ; they are tilted at a 

 high angle, the strike is nearly east and west, and the total thick- 

 ness of beds shown is about 190 feet. 



East of Kent's Hill, a short distance south of Dulverton Station, 

 is Hulverton Hill, a prominent hog-backed ridge, about 670 feet 

 above sea-level, with a quarry on its south-eastern slope. The 

 beds are nearly vertical, with an east-and-west strike, and a 

 thickness of about 100 feet is shown. The beds are mostly of the 

 hard, light-grey variety, but some are dark or speckled dark and 

 white. Soft shaly beds are absent. Some of the lighter beds are 

 crowded with radiolaria, and these can also be seen as whitish specks 

 on the surfaces of some of the darker beds. Messrs. Champernowne 

 and TJssher ] state that some of the strata here are of thin fine- 

 grained grits in tabular layers ; but we failed to find any of this 

 character, and it is probable that the beds referred to are those in 

 which the radiolaria project slightly above the matrix and impart 

 a gritty feeling to the touch. 



1 Quart. Journ. Geol. Soc. vol. xxxv. (1879) p. 533. 



