All these hills, containing caves in their interior, and situate so near each other, seem to form a small chain, interrupted only by brooks, and which joins the more elevated chain of the _Fichtelberg_, in which are the highest mountains of Franconia, and from which flow the _Main_, the _Saale_, the _Eger_, the _Naab_, and many small rivers. M. Rosenmüller, and after him, others assert, that those which are in the hills to the north of the _Wiesent_, contain not a single fragment of bone, while those to the south are filled with them. In 1799, a cave, remarkable for its situation, was discovered, which connects in some measure those of the _Hartz_ with those of _Franconia_. It is the Cave of _Glücksbrun_, in the bailiwick of _Altenstein_, in the territory of _Meinungen_, on the south-western declivity of the chain of the _Thuringerwald_ (Blumenb. _Archæol. Telluris_, p. 15. _Zach. Monate. Corresp. 1800, January_, p. 30.) It is the same which M. Rosenmüller names _Libenstein_, on account of its being on the road from _Altenstein_ to this latter, which is a bathing place. There is a description of it by M. Kocher, in the _Magazin für Mineralogie_, by M. C. E. A. De Hof, 1st band. heft. iv. p. 427. The limestone in which it is situate rests upon bituminous schist, and, rising much upwards, comes to rest upon primitive rocks. The limestone varies in hardness and in the nature of its fracture, and contains marine petrifactions, such as pectinites, echinites, &c. In making a road, there was discovered an opening, from which a very cold air issued, which determined the Duke of Saxe-Meinungen to have it farther examined. A narrow passage, of twenty feet in length, was found, which led to a cave of thirty-five feet, having a breadth of from three to twelve, and a height of from six to twelve, according to the places, and terminated by a large piece of rock, which was removed. The labour of two years discovered and cleared a series of caves connected together, and of which the bottom rose and fell alternately. They terminate in a place where water flows; but various lateral fissures make it probable that there are still several caves which have not been opened, and that they perhaps form a sort of labyrinth.