A similar appearance of glossy polish is found on all the calcareous specimens from this country, which appear to have been long exposed to the action of the atmosphere. In some of these the surface is entirely smooth and even; in others, it is furrowed over with minute grooves and channels, intersecting each other with irregular curvatures, and resembling the appearance produced on the surface of compact limestone that has been submitted to the action of acids, or corroded by small marine worms.
It is not easy to determine the cause of this irregular destruction of the surface of limestone, whose substance appears to be entirely uniform: it is probably the same that gives it the glossy polish; but it seems doubtful, whether the agent producing it be the continual drifting of fine siliceous sand, or the action of the atmosphere under exposure to a burning sun. A similar gloss appears on the surface of many fragments of flint and compact siliceous limestone that have been long exposed on the surface of the soil, on the summit of Martre near Paris; and in this case, I think, it can only be referred to the action of the sun and atmosphere.
The chain of the Soudah or Black Mountains appears to be composed of this basalt; they rise to an elevation of about 1500 feet, being situated at a short distance on the south from Sockna, and extending about 100 miles in breadth from north to south, and in length as far as the eye can reach, from east to west; they are perfectly barren, of irregular form, occasionally broken into detached masses, and sometimes rising into cones. Their elevated plains are in some parts covered with the small spherical shining fragments above described. The latitude of this chain is from 28·40. to 27·30. north. Traces of basalt occur also near Tripoli, in lat. 32. at a spot called Black Dog, on the north of Beneabbas, and in a valley through which the road passes from Beneabbas to Benioleed.
2. An unrolled agate from Om el a Beed, near Zeghen, on the south of the Black Mountains. The occurrence of fragments of basalt, in this same neighbourhood, renders it probable that basaltic rocks exist in Situ, near the Pass of Kenair.
tertiary formations.
3. Two species of cardium, in a state of delicate preservation, resembling that of the shells of Grignon, near Paris, and embedded in a loose white sand, which has the appearance and degree of adhesion of coarse white sugar, from a gravelly plain on the north of Bonjem.
4. Slightly crystalline limestone, of a dark yellow colour, and loaded with fragments of organic remains, amongst which the most distinct are referrible to the genus Ostrea and Pecton. It is found in a mountain of Tripoli, thirty miles south of Benioleed. This limestone appears to be nearly of the same era with the Calcaire Grossier of Paris, and is separated only by a large desert plain from the deposit of shells last mentioned at Bonjem. The probable connexion of these strata with the tertiary formations in other adjacent parts on the coast of the Mediterranean, has been already suggested.
5. Soft, highly calcareous marl stone, of a light mottled gray colour, resembling in appearance the chalk marl of England: it is said occasionally to be streaked with red, and to contain modules of flint. It occurs in the Mountains of Mejdool, in lat. 26.
6. Quartzose sand dispersed through a matrix of indurated green clay, and affording the materials of which the town of Traghan is built.
It is probable that these two last specimens, 5 and 6, are from strata not more ancient than the chalk of England, and possibly connected with the tertiary formations, No. 3 and 4.