GEOLOGY 



whole smaller than those further south and there is an increased per- 

 centage of quartz and grit pebbles. From a study of the minerals in 

 the Pebble-bed Thomas also deduced the existence of a main current 

 from the south, joined near Burlescombe by a confluent westerly current 

 to which he ascribed a rise in the percentage of heavier materials north of 

 UfFculm accompanied by the appearance of new minerals such as garnet 

 and cassiterite. 



The Pebble-beds display much false bedding, are irregularly inter- 

 calated with beds, seams and masses of sand, and are locally represented 

 by sands with beds and seams of pebbles. There is no sharp line of de- 

 marcation between them and the overlying Sandstones in the lower part 

 of which occasional pebbles are found. 



Upper Sandstones. — The thick-bedded red sandstones which overlie 

 the Pebble-beds often display false bedding. They are irregularly per- 

 vaded by calcareous matter which stands out in an irregular network from 

 the softer sandstone, in many parts of the coast section, and obscures the 

 bedding planes. Their outcrop at Sidmouth is cut off by fault letting 

 down the Keuper marls at Chit rock. Thirty chains from this they 

 crop out at the base of the cliff and at the surface near Ladram Bay, 

 where faults repeat the base of the marls, so that their total thickness is 

 represented between the large Otterton outlier and the outcrop of the 

 pebble beds at Knowl near Budleigh Salterton and may not exceed 250 

 feet. Irregular calcareous concretionary brecciated bands occur in this 

 series, in several places ; they are well shown in the upper part, at Lad- 

 ram Bay and at, and near, Otterton Point, where Irving* noted subangu- 

 lar fragments of slate, vein quartz, trap, reddish granite, felspathic grit 

 and quartzite in one band ; the estimated position of the Otterton Point 

 beds is about 1 00 feet above the Pebble-beds. Whitaker ^ discovered the 

 jaw of Hyperodapedon in the Otterton Point beds in 1868. Dr. Johnston 

 Lavis ' discovered remains of Labyrinthodon in talus from the cliff on the 

 west slope of High Peak Hill. The horizon is considered by Metcalfe * 

 to be a bed of lighter colour in the Sandstones, not far below their junc- 

 tion with the overlying Marls. Dr. Carter also discovered osseous 

 structures in these localities. The junction of Sandstones and Marls is 

 sometimes, as at Windygate, difficult to find (through the sandy nature 

 of the base of the latter) and local intercalations are also met with, but 

 otherwise there is no sign of passage beds. 



The Sandstone outcrop is persistent but greatly attenuated through 

 faults in places, as at Payhembury. 



Keuper Marls. — These beds consist of red and green variegated, 

 cuboidally splitting marls, less calcareous toward their base and locally 

 sandy. They occasionally contain beds of sand-rock, 1 5 feet of which 

 caps the marl cliff at Seaton. Veins, filaments, and bands of gypsum 

 are common between Branscombe Mouth and Salcombe Mouth. Calcar- 

 eous or marlstone bands are also present, and in the lower beds shaly 



' Irving, ^art. Joum. Geo/. Soc. 1902, p. 153. ^ Ibid. May, 1869, p. 152. 



^ Ibid. vol. xxxii. p. 274. * Ibid. May, J884, p. 257. 



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