80 
climatic conditions, would lead us confidently to pronounce the 
age of the sulphur marls to be that of the Congeria beds*— 
before the appearance of Etna as a voleano—for the sedimentary 
deposits in the environs of Etna are always covered up by lava 
flows and volcanic products, and the oldest lavas and tuffs yet 
recognised as from the massif of Ktna are superior to the con- 
glomerates of quaternary age. This was a period of immense 
upheaval of the coast, even to 3000 ft.: what is now hill and vale, 
the scene of sulphur mining, was then on a level, or accessible to 
the sea—a sea rich beyond conception in organic life—animal 
and vegetable in profusion—seething under the torrid zone, and 
yielding from its decomposition of organic matter the hydrogen 
sulphide, which in the case of briny marshes or shallow lagoons, 
oozed through the calcareous bottoms, depositing its sulphur 
film by film, between each layer of brackish mud. The chlorine 
decomposing the hydrogen sulphide, and the gases bubbling 
through, both nascent hydrogen and the sulphides becoming 
free, and their bases deposited in fine layers of sulphur, the 
Celestite separating, and the hydrogen sulphide rising and 
escaping by percolation, and, as an Italian geologist remarked, 
each film of deposited sulphur may have taken a year in the 
course of its precipitation. Organic matter has such an affinity 
for oxygen that it decomposes peroxides, and reduces them to 
protoxides, and so the presence of organic matter is the 
reduction of sulphates to the state of sulphides. Celestite is 
thus decomposed into strontian sulphide, which in water readily 
gives strontian carbonate and hydrogen sulphide, and the latter 
by oxydisation leaves a deposit of sulphur. The same process 
applies to calcium as a base. Layers of Calcite, Celestite, and 
sulphur have thus been formed in Sicily and elsewhere, as seen 
in the deposits of Tertiary age, and throughout all geological 
time where the same chemical conditions exist. 
* These Congeria Beds are very peculiar brackish water deposits, like 
those of the Aralo-Caspian seas. On these beds the City of Vienna is built. 
For interesting particulars and explanations of this sub-division of the 
foreign Tertiaries, consult Phillip’s Geology, the edition with the valuable 
editing of Prof. R. Etheridge, 1885, Part II., p. 664 ; also Von Hauer, Die 
Geologie, &c., Vienna, 1878, p. 619 (et passim). 
