400 
SECOND REPORT-1 832 . 
From the tertiary formations we naturally ascend to the 
modern rocks of volcanic origin, since it is from the tertiary 
period that the monuments left by that mighty geological cause 
assume a character so distinctly marked, as neither to be over¬ 
looked nor mistaken by even the most cursory glance. The 
most important group of extinct volcanoes with which we are 
acquainted, that of Central France, attracted the attention of 
geologists from a very early period ; they were first noticed by 
Guettard 1751, and soon after described by Desmarets and St. 
Fond, and many others *. The more precise researches of the 
present day have produced the detailed and exact labours of 
Le Coq and Bouillet (still in the course of publication) ; but an 
English geologist, Scrope, has presented us with perhaps the 
most interesting account of this important district. By the 
peculiar mode he has adopted in the graphical illustrations of 
his beautiful work, (combining geological colouring with pic¬ 
turesque representation), he places all the most important fea¬ 
tures of the district distinctly before our eyes, thus enabling us 
as it were to travel ourselves over the whole country with him, 
while his letter-press insures us the society of a most intelligent 
guide f. 
The volcanic district of Eiffel and the Rhine, was years ago 
most ably described by Noegerroth and Steininger ; and one of 
its most interesting portions, the basin of Neuwied, has very 
recently been made the subject of an elaborate monograph by 
our own countryman Hibbert; Schultz (Arcliiv fiir Bergbaa) 
has also published on the same subject. Boue has also re¬ 
cently materially enlarged the information which Beudant had 
previously communicated on the volcanic districts of Hungary. 
With regard to active volcanoes and their general theory, we 
have also to notice many most valuable recent contributions : 
the general essays of Daubeny and Scrope require to be 
carefully consulted; but by far the most important contribution 
which volcanic geology has ever received is Von Buch’s physical 
description of the recent volcanic district of the Canaries ; in 
this he has included the most masterly general survey of the 
whole volcanic subject, tracing the general range of volcanic 
lines over the globe, the particular configuration and relations 
of single groups, the characters which distinguish the volcanic 
products of different periods, and their general analogies with 
the early unstratified and probably ignigenous rocks ascending to 
* Desmarets in 1768, from his observations in Auvergne, first ventured on 
the hypothesis that the basalt of that district was a volcanic product. 
f Mr. Scrope has also communicated to our Geological Society some impor¬ 
tant papers on the Ponza Isles. 
