132 M. CirARBAUT on <^e 



stripes, marked by different colours, the most general and 

 best determined of which are — white, green, violet, red, 

 grey, and blue ; I shall describe them under the name of 

 variegated marls (marnes irisees). 



These marls, generally compact and granular, schistose 

 only in the grey and blue portions, are slightly aggregated ; 

 they contain more solid beds of different kinds. 



A bed of whitish limestone analogous to that which I have , 

 noticed in the gypseous marls, but coarser, is first seen im- 

 mediately above the gypsum rocks.* 



There exists, at a distance from the gypsum that I have 

 not yet been able precisely to determine, a bed of very poor 

 schistose coal, the ascertained thickness of which, for a great 

 extent, is between twelve and thirty centimetres [5 inches 

 to 1 foot 2 inches.] 



At some metres above, a considerable thickness of beds of 

 a dirty white limestone occurs, divided in every direction by 

 spathose veins, which, resisting better than the limestone 

 the destructive action of air and water, often give it appear- 

 ance of being divided by partitions. 



The variegated marls afterwards contain isolated beds of 

 siliceous sandstone with impressions, of a thickness varying 

 from 3 to 32 centimetres [about 1 inch to 1 f. 3 in.] The 

 organic remains enveloped in them at the time of their for- 

 mation, appear to have been in such an altered state, that it 

 is extremely difficult to determine their nature. 



This sandstone contains nodules and veins of pyrites, the 

 decomposition of which often communicates to it a strong 

 ochre red colour. 



Higher up beds of limestone occur almost solely composed 

 of the debris of very small shells ; the common thickness of 



* These marls will be at once recognised as the upper portion of the 

 tiew red or saliferous sandstone. A good section of variegated marls will 

 be seen under the lias, from Culverhole to Axmouth Points, on the coast 

 of Devon ; between Lyme Regis and Seaton, thin seems of gypsum will 

 also be observed among them. (For sections of this coast see Geol. Trans, 

 vol. I. new series, plate viii.) Trans. 



