128 PROCEEDINGS COTTESWOLD CLUB 1913 



Commercial Uses. — In times past the Lower-Lias clay has 

 been extensively used for brickmaking. That dug at the 

 Cotswold Potteries, however, had to have a " lighter loam " 

 from Leckhampton Hill (24) mixed with it before it was fit 

 for use.^ 



Middle Lias. — For a reason already given (p. 126), the 

 precise line of demarcation between Lower and Middle Lias 

 is difficult to determine. Roughly speaking, however, the 

 lower portion comprises sandy, shaly clays (more so than those 

 participating in the formation of the upper portion of the 

 Capricornus-Zone) and a Rock Bed, which is generally called 

 the " Marlstone." 



The tract where the Middle Lias crops out has been 

 mapped as accurately as possible, but, although the outcrop 

 areas of both " Sandy Beds " and Marlstone are approximately 

 shown, it must be mentioned that from a soil standpoint the 

 ground is clay land. 



For purposes of applied geology it is unfortunate that the 

 division-line between the Lower and Middle Lias has to be 

 drawn between the Capricornus- and Algovianus-lB>ediS, because 

 the upper part of the former and practically the whole of the 

 latter is sandy, which means that the spring-line does not 

 coincide precisely with the lower limit of the Middle Lias. 



The Sandy Beds are best seen in the old sunken trackway 

 near Timbercombe (17), whilst their characteristic flora is to 

 be seen on the slope of Shurdington Hill (16). 



The Marlstone is but poorly exposed in the area under 

 consideration, being visible only at : 



16. Where it is seen as a very red rock, being highly-coloured by 



iron oxide, and at 



17. WTiere it is seen above the Sandy Beds in the sides and near 



the top of the deeply sunken ancient trackway. 



Water. — At or near the base of the Middle Lias is an 

 important horizon as regards water-supply, because many 

 springs issue thereat. 



I Vide L. Richardson and R. Webb, " Brick-earths, Pottery, and Brick-making in Gloucester- 

 shire," Proc. Cheltenham Nat. Sci. See, n.s., vol. i., pt. 4 (igio), pp. 261-264. 



