GEOLOGY 



between the Blackdowns and the Haldons, and in the large outliers 

 of Great and Little Haldon rest on the lower beds of the New Red 

 Sandstone series. 



The Cretaceous tableland is capped by an accumulation of clay 

 with flints and chert and coarse gravel, which is considered to be of 

 Eocene (Bagshot) age by Reid. In the broad depression of the valley 

 of the river Bovey and between Milber Down, Kingsteignton, and New- 

 ton Abbot the Eocene clays, sands and lignite beds occur, and the sands 

 and gravels often dip sharply under them from off the higher ground on 

 their margin. A smaller flat at Petrockstow, north of Hatherleigh, is also 

 probably an Eocene lake basin, as it contains similar white clay to a depth 

 of over 80 feet and lignite veins were said to occur in it. Here also 

 sands and gravel containing cretaceous fragments are found. Quartz 

 gravel with flints occurs near Rivaton farm 4 miles to the west of 

 the Petrockstow depression at about 500 feet above the sea level ; and 

 flint gravel at Orleigh Court 5^ miles in a north-north-west direction 

 from the Petrockstow depression. These occurrences, to which a 

 patch of flint and quartz gravel at Colford, near Yeoford, may be 

 added, suggest the extension of Bagshot sands and gravels, if not of 

 Cretaceous rocks, over a considerable part of the Culm Measure area. 



The presence of patches of New Red rock at Broad Sands (on the 

 Paignton coast), at Durl Head (near Berry Head), at Slapton and Thurle- 

 stone, and at Portledge mouth on the northern coast, tends to show that 

 a considerable part of the coast line of the older rocks has been deter- 

 mined by the old margin of the New Red rocks. 



The inliers of older rock, such as some of the Lower Culm lime- 

 stone hills (near Burlescombe), the Culm Measures of Spraydown (south 

 of Bradninch) and the Devonian rocks of the Torquay promontory, are 

 not far from the older rock margin ; they prove that the floor of the 

 older rocks on which the earlier New Red sediments were deposited 

 was uneven or hummocky. 



The Lower New Red breccias and sands appear to have been 

 gravelly accumulations carried down by torrential rivers into broader 

 channels or lakelets, where they passed out into and inosculated with 

 sand. From vents in or bordering these channels trappean rocks were 

 locally outpoured, and, overlapping the sediments already formed, en- 

 croached on the older rocks, as may be seen in the relations of the 

 patches spared by denudation near Dunchideock, Poltimore, etc. There 

 appear to have been masses or dykes of quartz-porphyry in the main 

 areas of deposit in the Crediton valley and in the district south of 

 Exeter, as the boulders of that rock are often large enough to forbid 

 transport from a distance, and there is no source in the exposed area of 

 older rocks from which they could have been derived. Felsitic rocks 

 in line with and vicinity of the Crediton valley confirm this supposi- 

 tion. Ormerod called attention to the large percentage of felspar crys- 

 tals of the variety known as Murchisonite in the Lower New Red 

 breccias south of Exeter. To account for these phenomena R. N. 



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