On the Geology of Padua, Vicenza, and Verona. 17 
attempted any general account of them since Fortis, Strange, 
and Arduino. The Count Marzari Pencate has never published, 
and probably never put in order, the result of his researches on 
these points, which Brocchi, in the preface to his Catalogo 
Ragionato, hints to have been extensive. The cause of this 
silence is probably that little can be added to the accounts of 
Fortis, who in his last work, Mémoires de Géologie, published 
at Paris, 1802, satisfactorily proves these trap-rocks to owe 
their origin to the eruptions of submarine volcanoes; and I 
believe it myself impossible for any unprejudiced observer, 
with sufficient knowledge of the nature and characters of yol- 
canic phenomena, to dissent from this opinion. These erup- 
tions appear to have been confined to a broad band of country, 
extending from the southern flanks of the Monti Baldo and 
Gramulone to the neighbourhood of Monselice at the extremity 
of the Euganean hills. Whether this line is to be considered 
as an embranchment from the great trap district above, disco- 
vered by Marzari in the Tyrol, must depend ona similarity of 
constitution and position, which I have as yet had no opportunity 
to ascertain. The long and sloping ranges of sub-alpine hills 
which border the valleys of Ronca and Ciampo, as well as the 
two groups of the Monti Berici and Euganei, occupy this 
band; and I cannot but think it evident, that their peculiar 
situation, projecting like a series of promontories into the flat 
plain of the Po, and rising to a considerable elevation above its 
surface, is entirely to be attributed to the frequent mixture of 
trap rocks with the calcareous strata of which they chiefly 
consist, and the superior resistance they have, thus strength- 
ened, been enabled to offer to the power which excavated, 
levelled, and paved with boulders the remainder of that im- 
mense valley. 
In the trachyte (vulgarly called masegna) of the Euganean 
hills, I recognised the greatest general resemblance, and in 
many instances a complete identity with some of the trachytes 
of central France. The prevailing distinctions are, that the 
masegna sometimes contains quartz, and seldom or never 
augite, and exhibits a larger proportion of hornblende and 
Vox, XIV. C 
