183 
There is, I think, nothing contrary to our knowledge of 
physical processes in this hypothesis. It will be seen that the 
per centage of lime in the rock is high. We have innumerable 
instances of the formation of calcareous beds in relatively very 
short periods, due to the precipitation from solution of Carbon- 
ate of Lime. I need hardly refer to the classical instance 
recorded by Lyrtx of the discovery of a 14th century cannon 
embedded in a hard calcareous rock at the mouth of the Rhone. 
Again we know from our text books the effect on beds of 
minerals which decomposing animal and vegetable matter 
exerts. The re-arrangement of the mineral constituents of a 
partially consolidated mass by this means is familiar to the 
student of Geology. Our.colleague Mr EK. Wretuerep has made a 
series of observations on this subject. Suppose the large 
Ammonites and other Mollusca and Brachiopoda were suddenly 
entombed in a mass of silt consisting of sand and water highly 
saturated with Carbonate of Lime. They would speedily be 
killed, and decomposition would set in. The Carbonic Acid 
(CO,) of their decaying bodies would dissolve the Carbonate of 
Lime (CaCO,) in the presence of water, forming the Bicar- 
bonate (CaH, 2CO_,) which would again decompose into Lime 
Carbonate, water and Carbonic Acid, and the Carbonate of 
Lime would bind the particles of sand together in the manner 
in which Dr Smrrue tells us he finds this Kellaway’s Rock to 
be formed. The iron would probably undergo a somewhat 
comparable decomposition by the action of the Carbonic Acid, 
_ and be re-deposited as the Carbonate of Iron. The presence of 
_ Tron Pyrites is, we know, a feature of most fossiliferous beds 
in the Jurassic system. 
Other things being equal the diffusion of the gases from 
the dead animals would proceed at the same rates roughly, 
solution and re-deposition would follow each other, and the 
sand would be bound by the calcareous matrix in roughly 
_ defined areas, probably comparable to the successive eccentric 
shells I have endeavoured to describe. I submit this explana- 
_ tion of the phenomena as one which appears to have at least a 
: balance of probabilities in its favour. 
