GEOLOGY 



often east and west than north and south. The developments of breccia 

 in the Crediton valley, and of the older boulder breccias south of Ide, 

 are to be expected in areas of active vulcanicity, where deposition was 

 taking place. The association of rhyolitic rock with andesite^ overlain 

 by an outlier of Lower New Red at Horswell House near Thurlestone 

 is confirmatory of this view. 



Trap Rocks. — The trap rocks range in composition from trachytes 

 or orthophyres to basalts or melaphyres (Teall, Exeter Memoir, p. 33). 

 They occur in local clusters or as isolated patches, which are the relics 

 of many sheets or flows of lava emitted from different eruptive foci. 



The distribution of the traps with reference to the Lower New Red 

 sands and breccias is such that it is impossible to regard them as the 

 products of a single period of eruption, unless it be conceded that the 

 coarse breccias with igneous fragments which overlie them at Dun- 

 chideock and many other places are higher in the series than the sands 

 which underlie them in the Killerton district. 



If we take the traps collectively as an horizon in the New Red 

 rocks the relations of the lower sub-divisions of the group must be 

 regarded as interchangeable to a much greater extent than can be 

 proved to be the case. On this assumption the thick series of marls 

 with beds of sandstone between Exmouth and Straight Point might 

 indicate the outward passage of the coarser marginal deposits into finer 

 sediments. The overlying marls would then be the upper beds of the 

 Permian, and the Budleigh Salterton Pebble-beds the base of the Trias, 

 as advocated' by the Rev. A. Irving.^ 



Although contemporaneous trap rocks do not occur in the coast 

 section, the horizon of the Dunchideock trap would appear to be below 

 the boulder-bearing breccias of the Teignmouth and Labrador Inn coast, 

 and above the breccio-conglomerates of Watcombe, Petitor, Oddicombe, 

 etc., which die out northward from Newton Abbot. The acceptance of a 

 definite trap horizon would therefore place these breccio-conglomerates on 

 the same horizon as the sands underlying the Killerton trap rocks. 



A volcanic agglomerate is often associated with the traps (at 

 Pocombe, Culmjohn near Killerton, Posbury, etc.), identical with the 

 ' thonstein porphyr ' of Germany. The obvious correlation of the traps 

 with the German Melaphyr decken, or Middle Sotern, renders the cor- 

 respondence of the rocks above the Watcombe conglomerate with the 

 Upper Sotern and Wadern beds of the Nahe sections very probable, as 

 there are many points of resemblance. The Watcombe conglomerate, 

 etc., would then be Lower Sotern. 



T. M. Hall ' described the occurrence of a thin porphyritic grani- 

 toid vein in the New Red cliff at Portledge Mouth on the north coast. 

 The breccia and sandstone outliers at this place are in line with the out- 



* Pnc. Geol. Assoc, vol. xvii. pt. 3, p. 131. 

 " ^art. Joum. Geol. Soc. for May, 1888, p. 149. 

 " Hall, Trans. Devon Assoc. 1879. 

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