It appears to Mr. Buckland, from these specimens, that the kingdoms of Tripoli and Fezzan present, in their geological structure, a striking resemblance to the rocks of Europe; and are composed of strata, which are distinctly referrible to the three following formations:
- 1. Basalt.
- 2. Tertiary Limestone, of nearly the same age with the Calcaire Grossier of Paris.
- 3. New Red Sand Stone.
1. The Basaltic Rocks appear to constitute the great chain of the Soudah or Black Mountains, near the northern extremity of the kingdom of Fezzan, not far from Sockna; they extend in breadth nearly 100 miles from north to south, and run as far as the eye can reach from east to west.
2. The Tertiary Limestone, or Calcaire Grossier, containing marine shells in a state of delicate preservation, is found in Tripoli, on the two opposite edges of the desert that lies between the town of Benioleed and castle of Bonjem, and appears to be of the same age and formation with depositions of a similar kind that occur in Malta and Sicily, and on the north side of the Mediterranean, on the coasts of Italy and France.
3. The New Red Sand Stone formation appears under its usual form of loose red sand, accompanied by salt and gypsum, and associated with beds of a calcareous breccia, cemented by magnesian limestone, and with beds of compact dolomite.
There are no primitive rocks, and one specimen only which seems referrible to a granular quartz rock, more ancient than the new red sand stone.
A short descriptive catalogue of the specimens which have been brought home, with the assistance of the map in which all the names alluded to are inserted, will give the most ready information they are calculated to afford.
The specimens are as follow:
basalt.
No. 1. Basalt, nearly black, much impregnated throughout with carbonate of lime, and interspersed with small circular cells, that are partly or wholly filled with common or with magnesian carbonate of lime. The decomposition of this rock forms small spherical fragments of considerable hardness, the surface of which, by long exposure, has acquired a kind of polish or glossy aspect, and is irregularly pitted or indented all over with small cavities of various depths, from the destruction of the calcarous matter that originally filled them.