334 STKATIGKAPHICAL GEOLOGY 



Near Dawlish and Exeter the breccias graduate iipward into 

 sandstones, and these are succeeded by red marls with lenticular 

 beds of sandstone, which seem to be an upward continuation of the 

 series. These marls may be of Thuringian age, and consequently 

 homotaxial equivalents of the Magnesian Limestone Series described 

 below, though never actually connected with that series. 



How far these Permian rocks extend eastward beneath the 

 Trias and newer strata we have no means of knowing, but they 

 certainly had a considerable extension southwards, for patches of 

 them occur between Bolt Head and Plymouth, and fragments of red 

 breccia have been dredged from many parts of the sea-floor south- 

 east of Cornwall, in such fresh condition as to indicate the existence 

 of submarine reefs of this rock. 



3. North-Eastern Area 



In this area we have undoubted representatives of the 

 Thuringian stage in the form of fossiliferous magnesian limestones 

 with intercalated red marls. The outcrop of this series is shown 

 on the map (Fig. 87), from which it will be seen that although the 

 strike of the Permian Beds is at first nearly in accordance with that 

 of the underlying Coal-measures, yet they do not participate in the 

 anticlinal flexures which give an east and west strike to these 

 measures in South Durham. Near the valley of the Tees the 

 Permian oversteps the Coal-measures, and rests first on the Mill- 

 stone grit, and then on Carboniferous limestones. Farther south 

 it again crosses the Millstone grit onto the Coal-measures of York- 

 shire and Nottingham, but it is everywhere unconformable to the 

 latter. 



There is a marked lithological change in this series as it is 

 followed from north to south. In Northumberland and Durham 

 it is composed almost entirely of magnesian limestones (i.e. 

 dolomites), and the complete succession of beds, according to Dr. 



Woolacott's 7 recent examination of them, is as follows : 



Feet. 



Red marls with thin limestones and beds of salt .... 500 

 'Upper limestones, bedded for the upper 100 feet, con- 

 cretionary for some 200 feet, with a bed of flexible lime- 

 stone at the base (lft.fcet) 300 



Middle limestones bedded yellow limestones on the coast 

 replaced westward by compact fossiliferous limestones, 

 both often much altered and brecciated . . . 150 to 300 

 k Lower bedded brown limestones . . . . . 40 to 200 

 The Marl Slate (a brown calcareous shale) ..... 

 The Yellow sands (soft and without fossils) . . . to 150 



Total about 1200 



