Mr. Lonsdale on the Oolitic District of Bath. 245 



Ft. In. 



Compact limestone 1 



Brownish clay 1 



Compact limestone, three beds 1 2 



Rotten stone 2 



Compact limestone, three beds 1 4 



Rotten stone 2 



Compact limestone 6 



Parting of pale brownish clay 1 



Compact limestone 2 



Ft. In. 



Parting of pale brownish clay 



Compact limestone 2 



Pale brownish clay o 1 



Compact limestone {) 3 



Rubbiy limestone o | 



Compact limestone o 2 



Rubbiy limestone o 4 



Compact limestone, the lowest bed 



which has been worked o 3 



Of these strata^ that called the ''sun bed" is the most uniform in its cha- 

 racters, and accompanies invariably the white lias. It is an exceedingly 

 fine-g-rained stone, of a conchoidal fracture, blue in the centre, but pale brown 

 on the exterior. Of the remainder, those to which names have been given 

 are best known. They constitute in general the surface of the country ; and 

 the expense of removing the rubbiy beds which immediately succeed them, 

 prevents the lower portion of the series from being worked. The "blue lias" 

 consists principally of compact limestone of a dull, eartliy aspect, but it some- 

 times assumes a minutely crystalline structure. The "white lias" is of a 

 compact texture, sometimes of a conchoidal, but more often of a flat or 

 uneven fracture. In some of the strata irregular streaks of clay traverse the 

 stone, and give it a rubbiy or rotten nature. Organic remains are more or 

 less abundant in all the beds. 



The lias of Radstock is distinguished from that of Bath, by the absence of 

 the marls which are interstratified with the stony beds in the neighbourhood 

 of that city ; by the blue lias being in some places wanting, and by one of the 

 strata assuming a granular structure and oolitic appearance. It is called by 

 the peasantry " bastard or inferior oolite." The following section, taken from 

 the memoir on the "South-west coal district of England*," gives the best 

 type of the order of superposition at Radstock. 



Top. Fath. Ft. In. 



1. Blue clay 13 



2. Gritty lias 4 



3. Blue clay 1 6 



4. Corn grit (three beds) 1 6 



5. White lias 2 



6. Knotty claystone 1 C 



7. Grey or blue marlstone 5 



8. Dark marlstone 1 



9. Black marl 2 



* Geol. Trans. 2nd Series, vol. i, p. 278. 



c 



