Geological Society of London. 77 
logical structure, embracing the transition and secondary rocks of the 
Hartz, Thuringerwald, and Lower Rhine. In the larger map all the 
tertiary and alluvial deposits are represented by one color, the au- 
thor having never entered upon the subdivision and classification of 
these formations. He had studied, however, the newer secondary 
formations, which were depicted by several distinct colors, and their 
history would have been included in the work above alluded to, had 
he not been interrupted by his tour‘in Italy and Sicily in 1830. 
Among his other writings, I may enumerate an Account of Mag-— 
deburg, Halberstadt, and the adjoining territory, and various papers 
which will be found scattered through the journals of Poggendorff 
and Karsten, the Hertha, and other German periodicals. The only 
fruits which we as yet possess of the scientific expedition sent by the 
Prussian Government under Hoffmann’s direction to Italy and Sicily, 
are some letters written by him during the journey, and an excellent 
Memoir on the Lipari Islands; and a valuable work by one of his 
companions, Dr. Philippi of Berlin, who published in Latin a de- 
tailed account of the recent testacea of Sicily, and the tertiary fossil 
shells collected in the course of the expedition.* 
From Hoffinann’s letters it clearly appears that the novelty of the 
volcanic and tertiary phenomena of Southern ltaly and Sicily had 
made a deep impression on his mind. He had been astonished, on 
recognising the identity of the modern trap rocks of the Val di Noto 
with those of ancient date in Germany, and the no less striking simi- 
larity of the Sicilian tertiary limestones, containing recent shells, to 
many calcareous secondary formations of northern Europe. 
Lipari Islands afforded him a field for the examination of modern ig- 
neous rocks, and the slow effects of volcanic heat in modifying aque- 
ous deposits. The picture which he has given of the fumeroles of the 
western coast of Lipari, the principal island of the group, is graphic 
and highly instructive. At St. Calogero numerous fissures are seen 
permeated by heated vapors which are charged with sulpbur, oxide 
of iron, and other minerals, in a gaseous state. Here the tufaceous 
and other rocks are variously discolored wherever the steam has pen- 
etrated, and are sometimes crossed with ferruginous red stripes, so as 
to assume a chequered and brecciated appearance. In one place a 
feldspathic lava has been turned by the vapors into stone as white 
+ Phillippi, “Enumeratio Mollascoram Sicilie tum viventium tum in tellure 
tertiaria fossilium, qu@ in Itinere suo observavit Auctor.” 280 pages 4to, and 12 
lithographic plates, Berlin, 1836, 
