South-Western Part of Somersetshire. SG^ 



Remains of a pentacrinite, resembling that which is found on 

 the banks of the Severn, near to Pyrton passage. 



Fragment of a large compressed and strongly ribbed ammonite. 



Slight remains and traces of some unknown pinnated vegetable 

 converted into coal. 



Remains of terebratulse, much resembling T. lacunosa. 

 ' Fragment of a large shell of the genus nautilus. 



In several places the surface of the limestone strata is exposed for a 

 considerable way, shewing that in many instances they do not con- 

 sist of a continuous mass, but of an accumulation of columnar dis- 

 tinct concretions, resembling the Giant's Causeway on the coast of 

 Antrim. These concretions are distinctly separated from each other, 

 all their angles are rounded, and there is no regularity in the number 

 of their sides or their dimensions ; in some of the strata the whole 

 surface of each concretion consists of that brown crust mentioned 

 above, enveloping a light blue nucleus. This structure of the lime- 

 stone makes it very easy to work, as it is only necessary to separate the 

 concretions with an iron bar. In this way a great many of the beds 

 near low water mark are worked, and the concretions are brought in 

 paniers on the backs of little horses and asses to the kilns on the top 

 of the cliff. I observed a similar structure in the red rock, but the 

 divisions were much smaller than in the limestone strata. In both 

 instances the appearance is very like that of a mass of dried clay or 

 starch. "When the strata of limestone are not divided into those co- 

 lumnar concretions, they are generally separated into large irregular 

 shaped masses by joints perpendicular to the stratification, and in 

 many parts they are penetrated in every possible direction by con- 

 temporaneous veins of jcalcareous spar crossing each other like net- 

 work. They seldom exceed a few inches in thickness, and are in 

 general much more slender ; the same vein which in the middle is an 

 Vol. III. 3 a 



