112 Horace B. Woodward — On Landscape Marble. 



Khaetic Beds at Garden ClifF, Westbury-on-Severn ; and it is an 

 exceedingly irregular and nodular limestone. 



In other formations I have met with similar phenomena. In the 

 Lower Purbeck Beds at Durlston Bay, near Swanage, there is a thin 

 layer of limestone that presents the same corrugated and mamrail- 

 lated surface as the Cotliam Stone, and it exhibits obscure arborescent 

 markings. Again at Kounden Wood near Battle, a layer presenting 

 like characters, occurs also in the Pui'beck Beds. In the same dis- 

 trict near Battle, there is a bed of more or less nodular limestone 

 called the ' Cutlets,' and this sometimes possesses curious irregular 

 bands of light and dark grey tints, that form a sort of intermediate 

 stage between even banded limestone and Landscape Marble. There 

 is a specimen of this rock in the Museum at Jermyn Street. 



Another illustration 1 bave met with in the Inferior Oolite of 

 Cbarlcombe, near Bath, where there occurs a bed of compact brown 

 limestone, banded at the base like the Gotham Stone, and becoming 

 nodular (and in this case also somewhat concretionary) above ; and 

 this rock exhibits faint resemblances to arborescent markings. 



For want of a better explanation I have elsewhere compared the 

 arborescent markings in the Landscape Marble with the dendritic 

 infiltrations of manganese-ore, etc., so commonly met with on the 

 surfaces of rocks, whether along joints or bedding-planes.^ I now 

 think there is no particular connexion between the phenomena of 

 infiltration and the production of the Landscape Marble. 



The ferruginous infiltrations that produce irregular bands of colour 

 throughout the mass of many rocks, present no close resemblance 

 to the features of Landscape Marble. Some of the appearances met 

 with in the fissile limestone known as ' Florentine Slate ' and ' Euin 

 Marble,' are due to infiltrations of oxide of iron that permeated the 

 stone probablj'^ after consolidation ; while the rock itself, thus ii'regu- 

 larly banded, was subsequently fractured, and portions of it shifted 

 by minute faults that have given the sharp outlines to the " ruins." 



It may be mentioned that other beds of limestone above the 

 Gotham Stone, and as high as the ' Sun Bed,' which is locally the 

 top layer of the White Lias, occasionally present irregular and 

 corrugated surfaces, but these occur in homogeneous limestone, and 

 no arborescent markings are exhibited. The fact indirectly lends 

 support to the view that the arborescent markings of the Gotham 

 Stone are contemporaneous and not due to subsequent infiltration. 



There is no evidence to support the notion that gaseous emanations, 

 such as might have arisen from the black mud of the Avicula contorta 

 Shales, had anything to do with the formation of the Landscape 

 Marbles. This notion was to a certain extent suggested by E. Owen, 

 who thought the arborescent markings were produced by the escape 

 of imprisoned air ; but had such agents been at work the markings 

 would not be confined to the nodular masses of rock, and they 

 would extend upwards through the base of the limestone. 



It appears to me that the arborescent markings were produced 



^ Geol. E. Somerset, etc, (Geol. Survey), p. 70 ; and Geol. England and "Wales, 

 ed. 2, p. 244. 



