THE TRIASSIC SYSTKM 367 



A continuation of these bed*> is found in South Wales, where 

 they occur in patches from Cardiff westward as far as Forth Cawl 

 and Ken tig, with a small outlier in Qower which indicates a still 

 1'urt IHT extension to the west. The beds surround islands of Old Red 

 Sandstone and Carboniferous limestone, and their thickness, of 

 con i -.-(, varies, but there is generally a border or base of dolomitic 

 breccia which passes up into red marls with layers of red and 

 wliitf limestone ; these are succeeded by red clays, and, finally, by 

 green clays or marls. 1 - 



On the Somerset side of the Channel a similar set of red breccias, 

 >andstones, and marls is found all round the Quantock Hills, and 

 along the coast from Watchet to Porlock, where they occupy an 

 ancient strait between the Brendon Hills and that called North 



Fig. 121. SECTION TO SHOW THE RELATIONS OF THE TRIAS TO THK CARBONIFEROUS ROCK* 



NEAR SHEPTON MALLET (Somerset). 



I. Lower Lias. 4. Millstone grit, 



r. Rluetic Beds. 3. Carb. limestone. 



k. Keuper marls. 2. Carb. shale, 



c. Conglomerate. 1. Old Red Sandstone. 



Hill on the coast line. The Quantock Hills were an Island in the 

 great lake, and the Trias is bedded into a similar old valley or 

 strait on the west of them. 13 



5. Devonshire 



South of Taunton the thickness of the Keuper Series becomes 

 greater, though the actual outcrop is narrowed by the overstep of 

 the Cretaceous strata which form the Blackdown Hills. The 

 whole series, however, is well exposed on the cliffs of the south 

 coast, from Sidmouth to Seaton and Axmouth. Here the following 



succession of l>eds is found : 



Met 



( Red and green marls . . about 300 



Keuper-! Red marls with gypsum . . ,, 1000 



(.Red sandstones . . . . ,, 75 



Keuper. According to Professor Hull and the Rev. A. Irving, 14 

 the base of the Keuper division should be taken at a bed of hard 

 breccia about two feet thick which can be seen below the footbridge 



