104 PALAEOZOIC TIME. [CHAP. VII. 



stone, and the rocks consist chiefly of red sandstones with 

 occasional beds of calcareous breccia. Between Carlisle 

 and Penrith there are two massive sandstones, the lower 

 about 1,000 feet, and the upper about 1,500 feet thick, 

 separated by a zone of red shales. Near Appleby the 

 lower sandstone contains thick beds of breccia (locally 

 called brockram), consisting of pebbles derived from the 

 Carboniferous limestone, and the red shales have at their 

 base bands of magnesian limestone and impure coal. 



On the west side of the Lake District there is another 

 strip of Dyas, but the lower (Penrith) sandstone is not 

 present, and the basal beds at St. Bee's Head consist of 

 magnesian limestone with fossils (11 feet thick) resting on 

 a thin breccia of limestone fragments. 



Northward, in Dumfries and Ayr, rocks similar to the 

 Cumberland sandstones are found occupying several basin- 

 like depressions, and resting partly on Carboniferous and 

 partly on the older rocks. In Nithsdale and the valley of 

 the Ayr sheets of porphyrite and volcanic ash are inter- 

 stratified with the sandstones, and even the stumps of the 

 volcanic vents from which these materials were ejected 

 can be identified. 



Returning to England, small detached patches of Dyassic 

 deposits occur at intervals round the coalfields of Lan- 

 cashire, Denbighshire, Shropshire, Staffordshire, Warwick- 

 shire, and Worcestershire. The Lancashire beds resemble 

 those of Cumberland, consisting of a red sandstone over- 

 lain by red marls, shales, and limestones, with fossils of 

 the Magnesian Limestone type. 



Denbigh and North Staffordshire exhibit rather a dif- 

 ferent type, the beds being similar in both districts, and 

 consisting of dark red and purple sandstones, with red 

 marls and bands of cornstone ; these beds are only slightly 

 unconformable to the Upper Coal-measures. 



In the Shrewsbury, Bridgenorth, and South Stafford- 



