ROCKS OP SOMERSET AND DEVON. 385 



are faulted against breccia (lowest series), Conglomerates, Upper 

 Sandstones, and Upper Marls. 



Economic Uses. — The loamy clay soil affords material for brick- 

 making. The continuity of this division might almost be proved 

 by the numerous brick-pits in its soil between Burlescombe and 

 the coast, as in Leonard Moor, north of Tiverton Junction, east of 

 Collumpton, Clisb Hydon, near Exmouth, north of Burlescombe, at 

 Cutcomb Farm east of Wiveliscombe. South of Williton, a thick 

 drift-gravel often conceals the second marls. 



Thickness. — We have now to consider the slender evidence pro- 

 curable to assist us in arriving at an approximate estimate of the 

 thickness of this division. If we could take the bed of grey sand- 

 stone on the north side of the fault, south-east of Westdown Farm, 

 as the top bed of the Lower Sandstones, the breadth of outcrop*, 

 allowing a persistent dip of 5°, would give a thickness of 530 feet. 

 600 feet is the utmost I should be inclined to allow for the whole 

 division inland. 



If the sandstones of Straight Point are beds in the Marl, indi- 

 cating a local passage into the Lower Sandstones, and do not 

 represent the upper portion of the Lower Sandstones themselves, 

 they can scarcely add more than 300 feet to the thickness of the 

 Lower Marls in this part of the district, giving a total thickness of 

 830 feet. 



Unfortunately, inland we have no better data to go upon, as, in 

 the cases where the relation between the marls and their over- and 

 underlying beds are observable, their own structure is concealed. 

 Allowing the average breadth of areat they cover as the breadth of 

 outcrop, with a dip of 2° persistent, their thickness would be about 

 360 to 400 feet. 



The intercalations of sandstones with the marls on the east of 

 of Exmouth seem to indicate a passage into the upper member of 

 the lowest division in South Devon. 



Lowest Division. 



In considering this division (so far as we know, the lowest, and 

 certainly the most varied member) of the Devonshire Trias we must 

 treat the constituent parts, locally and lithologically, according as 

 they are represented by (lower) sandstones, hard breccias, breccio- 

 conglomerates, brecciated sands, brecciated loamy clays, or clays. 

 In so doing it must not be implied that beds in different localities, 

 of the same lithological character and composition, are either con- 

 temporaneous or occupy the same position in the division. 



Where present, in the area between Minehead and the south 

 coast, these beds present many different phases, occurring as sand- 

 stones and sands, brecciated sands and sandstones, gravelly breccias 

 (conglomeratic) clays, often brecciated with shale-fragments, sand- 

 stones, and sands which occur intercalated at any horizon. Gene- 



* 1£ mile. 



t About 2 miles, i. e. varying from 1 to 3. 



2e 2 



