South-west and North of France, and South of Germany. 129 
to acquire a perfect knowledge of the whole of the floetz and terti- 
ary formations, and to derive clear ideas of the structure of the 
secondary rocks of the Alps, seemed to be, in this period ol the 
science, the most important desiderata : and to arrive at these 
results, no country held out so many hopes as the south of Ger- 
many and France ; the truth of which presumption will be shown 
by my narrative. 
The geological structure of France is much more simple than 
that of Germany. A great elevated range of slaty and primary 
hills occupies the central point of that country (the limits of 
which see in Omalius d’Halloy’s Map of France). Around this 
kind of island are arranged three great secondary basins ; one 
called the South-eastern or Mediterranean, the second the 
Oceanic or South-western, and the third the Northern. The 
first lies between the Alps and the mountains of the Vivarais and 
Lozere; the second between the Pyrenees and the hills of La 
Vendee, the Limosin and La Montagne Noire : the third be- 
tween the chain of Bretagne and Cotentin, that of Auvergne, 
the Vosges and Ardennes. These three basins communicate 
with each other ; the south-western with the northern one, by the 
country around Poictiers ; and with the south-eastern by the 
neighbourhood of Carcassone; and the northern with this last 
between Vienne and Grenoble. Besides, the northern second- 
ary basin has a free communication with the basins of the north- 
ern, middle and southern parts of Germany, and with that of 
Switzerland and even of Hungary. The southern and more 
ancient part of the Vosges, the Black Forest, the Oden wald, 
the great schistose tract of Belgium and Westphalia, the Hartz, 
the hills around Bohemia with the Thuringerwald, and the cen- 
tral part of the Northern Carpathians, are so many islands of this 
immense ancient sea ; and the Eastern Carpathians are a vast pro- 
montory of the great Alpine island. 
The south-western basin of France is limited on the north by the 
transition countries of Vendee and Bretagne, which contain here 
and there masses of granite , surrounded by crystalline slates 
and traversed by porphyry veins, (Fond de la Boulogne), ex- 
hibiting the same phenomena as in the Erzgebirge. Some small 
patches of sandstone of the coal formation , and todtliegende , are 
also found here and there. In Limosin and Arveisin, we find 
vol. ix, no. 17. JULY 1823. 
i 
