202 Prof. W. King on Oceanic Sediments, and 



ginia, assuming that at one time they were like the Levant 

 mud, in whieh there is generally an admixture of ealcareous 

 and siliceous organisms *. 



There are certain facts in geology which show analogous 

 changes eftected by the agency of carbonic acid : the most 

 striking that occurs to me is tlie conversion, by means of this 

 solvent, of beds of argillaceous limestone (Carboniferous) into 

 highly aluminous rotten-stone, in Derbyshire and CJhimorgan- 

 shire. Nevertheless there are some grounds for refusing to 

 look upon the " red-clay " basins as so many Upas valleys. 

 If carbonic acid destroyed all the shell-structures carried into 

 them, the water would necessarily become charged with bi- 

 carbonate of lime in solution ; but from the A-arious analyses 

 hitherto made of sea-water, the quantity it contains of this 

 salt appears to be veiy small compared with the amount of 

 sulphate of lime. Carbonic acid may be the agent ; but I am 

 more in favour of sulphuric or rather sulphurous acid, con- 

 sidering that such is not unlikely to be produced by the oxida- 

 tion of sulphuretted hydrogen, derived from the decomposi- 

 tion of organic matter — also the presence of its decomposing 

 agent (oxygen), as determined by Messrs. Lant Carpenter 

 and Buchanan, in the depths of the ocean f. 



Subjected to the action of sulphurous acid, the substance of 

 all ealcareous shells in a dead condition would be ultimately 

 converted into soluble sulphate of lime, with liberation of car- 

 bonic acid J ; and thus the ocean would be perpetually su})plied 



• Transactions of the Manchester Literary and Philosophical Society, 

 1847. It must not be overlooked that tlie siliceous or<ranisms which 

 occur in the foraminifer-ooze in appreciable proportion have likewise for 

 the most part disappeared in the red clay, throiifrh the action of some 

 dissolving agent. Crystals of quartz, from Zinnwald, are not uncommon 

 with their planes corroded and deepl^y excavated in places originally occu- 

 pied by oligist — showing that the silica has been in some way removed 

 by the action of a ferric oxide; the fact is of some signiticauce in con- 

 nexion with the disappearance of the siliceous organisms from the red 

 clay. I may add that Mr. H. J. Carter has called attention to the rapid 

 wasting or decay which siliceous (also calcareous) spicules of sponges 

 underero in his cabinet, whether mounted or unmounted, also in living 

 specimens (see Ann. & Mag. Nat. Hist. 1873, vol. xii. pp. 4o(J, 4o7). This 

 destruction appears to be due to solvent action of anotlier kind. 



t I have had some experience of the presence of sulphuretted hydrogen 

 in the ocean during a strong gale of three days' duration on the west side 

 of the Doggerbank, while on one of my dredging-expeditions, some thirty 

 years ago. The agitation of the sediment at the depth of about forty 

 fathoms by the heavy seas caused so much of this gas to rise to the 

 surface that my watch, a silver one, became quite blackened by its 

 action. 



X When Bischof wrote his ' Chemical and Physical Geology ' very 

 little was known respecting the abundance of calcareous organisms at 

 the bottom of deep oceans. Fixing his attention on the vast amount of 



