Dr Daubeny on the Geology of Sicily. 259 
My reasons for assigning to it this date are, its containing 
beds of blue limestone with shells, some of which (as Turritellae) 
seem to bespeak a tertiary origin ; its being accompanied, through- 
out its whole extent, by the recent breccia above noticed ; and 
the probability that the amber of Sicily has been derived from 
this stratum,— a circumstance directly affirmed by Ferrara % 
and favoured by the situations in which this mineral is chiefly 
met with ; namely, at the mouths of rivers which have flowed 
through this rock. 
Should my inference appear hardly warranted by the above 
considerations, it will be borne out, at least, by the fact of the 
identity of this formation with the marl of Italy, described by 
Brocchi -f* *, which that able geologist seems to have good grounds 
for referring to the same recent period. The greater part of 
the country, at the foot of the Appenines consists, it would 
appear, of a calcareous sandstone, and of a brown or bluish 
marl. The recent origin of the latter is evinced by the trunks 
of trees buried in it, and preserved nearly fresh, by the leaves 
of vegetables, and skeletons of fish, in which the dried muscu- 
lar part may be recognised, and by the immense number of shells 
retaining all but their animal matters and colour, and sometimes 
even these. 
It contains, like the blue clay of Sicily, beds of sulphur, 
which is here of a liver colour, and which, according to our au- 
thor, has been sublimed ; thus giving rise to the production of 
the yellow variety, also seen in the marl of Italy, distributed 
through the cavities of the rock. Like the blue clay of Gir- 
genti, it gives rise to disengagements of inflammable gas, as near 
Modena J. It contains mineral pitch, amber, sulphate of lime, 
both massive and crystallised, sulphate of strontian, and sulphate 
of barytes. Common salt abounds in the marl of Italy, as in that 
of Sicily, which is proved by the salt- springs, so common in the 
vicinity of Cesena, Sienna, and Volterra. 
* Vide Ferrara Campi Flegrei, p. 29. 
*J- Vide Brocchi Conchologia Subappenina. 
X These phenomena are called Salses, or Air-Volcanoes. Is it possible that the 
inflammable gas of the Pietra Mala, between Florence and Bologna, may have 
originated from the same stratum, and have found its way through clefts in the 
older rocks, to the summit of the mountain, whence it escapes ? 
