CHAP. VII.] DYASSIC PERIOD. 105 



shire districts there is a similar set of beds, divisible into 

 three stages, the middle one (from 200 to 400 feet thick) 

 consisting of breccia and conglomerate, sometimes cal- 

 careous, and sometimes chiefly composed of felspathic ma- 

 terials large blocks of felstone, syenite, and volcanic tuff 

 occurring with boulders of quartz rock, limestone, sand- 

 stone, and slate; all these have probably been derived 

 from the Archaean, Cambrian, and Silurian rocks that un- 

 derlie the Dyas and Trias of the Midland counties. 



Further south still the Lower Sandstones disappear, and 

 at Church Hill, in Worcestershire, the breccia lies directly 

 on the Coal-measures, the fragments composing it being 

 very large and angular, and identifiable with rocks of 

 Cambrian and Silurian age lying to the north-west. Small 

 outliers of similar breccia rest against the Silurian of the 

 Abberley Hills, and the most southerly is that at Haffield, 

 at the southern end of the Malvern range. 



This incoming of breccias southward with a thinning out 

 of the lower beds is unequivocal evidence of a close ap- 

 proach to the southerly limit of the area in which these 

 deposits were formed, and the breccias are also a proof 

 that the shores were steep and rocky. 



The only other districts in England where rocks of this 

 age occur are, (1) Warwickshire, where they consist of red 

 sandstones and marls, with occasional beds of calcareous 

 breccia and conglomerate, the whole supposed to be nearly 

 2,000 feet thick, and (2) Anglesey, where similar beds to 

 a thickness of 400 feet overlie the Coal-measures. 



In Ireland three small patches occur in Ulster, fossi- 

 liferous magnesian limestone existing at Cultra, on Belfast 

 Lough, and at Tullyconnel in Tyrone, and Boulder beds, 

 with a limestone breccia at the base, rest on the Carboni- 

 ferous Limestone of Armagh. The blocks in the Boulder 

 beds are chiefly grits and sandstones derived from the 

 Silurian and Old Red Sandstone districts that lie to the 

 north-west. 



