140 
ON THE GOTHAM MARBLE 
(Thompson seems to think Owen’s theory was not the same 
as his own, and that the dark layer referred to wa,s the 
Black Shales. This scarcely appeals to be Ow^en’s mean- 
ing). 
ii. The Mineral Infiltration Theory — but the dark 
matter is carbonaceous, not metallic. 
iii. Rev. Osmund FisheRs Theory, that “ thicker layers 
of rotten plants gave way under the superincumbent tufa, 
which broke down, and the carbonaceous mud was forced 
up.” This fails to account for the concentrically banded 
branches, hummocky surface, and many other details. 
iv. Mr. H. B. Woodward’s Theory. “ The arborescent 
markings were produced during the consolidation of the 
stone, and more particularly by the shrinking of its upper 
portions. In this way, and while the mud was still in a 
more or less pasty condition, one or more of the dark 
films in the banded mass were disarranged and dispersed 
in an arborescent form in the slowly setting rock.” This 
took place in an ooze, “ occasionally exposed to the sun’s 
rays.” He admits that he may have “ appealed too 
strongly to mechanical causes as apart from the ob- 
scure processes of segregation or even of concretionary 
action.” 
There are many inadequacies in this theory. Why 
should the upper layer be dry whilst the lower was fluid ? 
Why was the fluid forced only up, not down as well ? How 
could this produce the concentrically banded “ hedge ” ? 
Why are the “ branches ” rounded and concentrically 
ringed, instead of tailing out into finer and finer arboriza- 
tions, as they would if filling cracks ? The theory also 
fails to account for “ islands,” gives no explanation of 
the extraordinary hummocky surface, and is totally at a 
loss to explain the False Gotham Marble. 
I have performed one or two experiments with wet 
powdered chalk resting on a mixture of oil, soot and 
