202 Dr. Bright on the Strata 



The last of these highly inclined strata at the base of their western 

 escarpment are generally covered by beds of a very different character, 

 which lie in horizontal layers upon the broken basset edges of the 

 lowest beds of sandstone. This arrangement of the two formations 

 may be observed to the south of the Avon on the towing-path just 

 where the beds of sandstone terminate, and to the north of the river 

 near to Sneed Park ; at these places the sandstone is covered by 

 horizontal beds of that kind of breccia which I shall presently de- 

 scribe. These horizontal beds form a series of low hillocks extend- 

 ing from where the sandstone terminates to within two miles of the 

 Severn. They are best observed on the southern bank of the Avon, 

 at Hung-road near to Crokerne Pill, where their section is exposed 

 at low tide in a perpendicular cliff nearly 60 feet high. The beds 

 consist of a red loamy earth and of breccia arranged in the following 



order. 



Breccia 3 or 4 feet 



Red loamy earth, about ... 30 



Breccia extending to the base of the cliff, and quite below 



low water mark. 



The upper and lower beds of- breccia present nearly the same 

 characters. They both consist of calcareous and siliceous fragments 

 cemented together by a calcareous ba?e, having cavities in it, which 

 are filled with calcareous and siliceous crystals, and sometimes with 

 sulphate of strontian. The calcareous crystals have either the form 

 of the primitive rhomb, or of the dog's-tooth spar, and are sometimes 

 covered over with an incrustation of smaller crystals of carbonate of 

 lime. The quartz is crystallized in six-sided pyramids. Besides the 

 sulphate of strontian which is found crystallized in the cavities in 

 small quantity, it occurs in large masses either imbedded in the 

 breccia, or lying between the two beds of it. It occurs in blocks of 



