Part of Gloucestershire and Somersetshire. 339 



Severn, correspond so perfectly in position and structure, that no doubt can 

 exist of their original connexion. The colour of these banks is very striking 

 even at the distance of several miles, appearing of a dark reddish brown, or 

 brownish red hue. Let us now consider their constitution. 



The formation exhibits considerable variety of character, consisting of beds 

 of stone, slate, clay, and marl, which frequently alternate with each other, 

 the clay and marl predominating. The ingredients composing these beds, may 

 be generally said to consist of grains of quartz, — red, iron shot, indurated sandy 

 clay, and clay marl, — with numerous scales of silvery mica ; from the different 

 size and intermixture of which substances arise the higher or lower state of 

 compactness and induration, and power of resisting disintegration, observable 

 in the different beds. The sandstone varies from the small to the minute 

 grained, in which the particles are scarcely recognisable by the eye. Occa- 

 sionally also, yellowish, opake, grains of felspar, sometimes passing into the 

 state of earthy felspar or white clay, are intermingled in the compound. When 

 the scales of mica become profuse, and are disposed in a parallel direction, a 

 slaty micaceous sandstone is formed. The clay beds consist of a predomi- 

 nance of indurated clay commingled with fine sand and dusty particles of mica, 

 the whole forming a tenacious compound, but which also frequently acquires 

 a slaty structure. The clay marl differs from the clay, only in containing a 

 proportion of carbonate of lime diffused through its substance ; and some of 

 the lower beds (which are probably not far removed from the subjacent tran- 

 sition tract) acquire a conglomerated structure, as at Sharpness Point and 

 in the Wheel Rock on the opposite shore, the base of clay marl enveloping 

 numerous small, irregularly angular and rounded portions of sandy micaceous 

 limestone, which, being less destructible than the clay marl, project above the 

 wasted surface of the latter *. The marly and clayey beds appear to diminish 

 in number and frequency, as we ascend in the series toward the Forest coal- 

 basin, the sandstone almost exclusively prevailing. This fact may be distinctly 

 observed by following the defiles, that lead up from Blakeney and Sidney re- 

 spectively into that coal-field, traversing in their course the stratification of 

 the country. 



The old red sandstone of the banks of the Severn, though in general of a 



* At the foot of the cliflF on the south-western side of Sharpness Point, I found a piece of the 

 sandstone which contains a few fractured remains, apparently referable to dentalia; much 

 resembling in form Dentalium elephantinum, with the exception of being imperforate. They 

 may have been originally derived perhaps from transition beds beneath ; but I have no where 

 observed this species of dentalium in the transition tract itself. In no other part of this range of 

 old red sandstone, have I perceived any vestige of organized bodies. 



