Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/224

 ern side being very precipitous. Its formation is also calcareous. It consists of a very compact limestone, generally of a red colour, owing to the great proportion of peroxide of iron which it contains. It makes a very good building-material, and has been largely employed in the construction of Antequera. On the eastern side it reposes in conformable stratification on a fine-grained and white oolitic marble, which attains a considerable thickness, the extent of which I was not able to determine with any degree of precision, although it appeared to me that it could not be less than 1000 feet. In the divisional line between the two formations there were many Ammonites, lying in a position perfectly parallel to the plane of stratification, and in the same place in which they were originally deposited, without having suffered the slightest disturbance. It is the red marble that presents the fantastic forms alluded to before.

At the top of the ridge there are large platforms surrounded by vertical rocks, which are scooped out horizontally in a continuous direction, being principally grooved at their base — so much so that in some places the top greatly projects, making the rock assume the form of a great table, while in other places the grooving is reduced to three or four yards above the level of the plateau, whilst the rest of the cliff remains vertical, having the appearance of long continuous caves. The platforms are generally perfectly plane and horizontal, although full of crevices and faults, which are sometimes of considerable depth. Large angular masses of detached rocks are found in all parts of these basins ; these, however, are more rounded; that is, their angles are not so sharp as those of the cliffs. We received the impression that these platforms had been the beds of ancient lakes, the water of which had subsided at certain intervals, but not in a gradual and uniform manner, causing certain levels to remain longer stationary than others, the lower ones enduring the longest. In support of this view, we found that the basins have generally an outlet through which they have been drained, so that we could easily trace to a considerable distance the direction of the current as it escaped from the lake. In many of these lakes (if I may so call them) there exist vertical caverns of great depth. The strata dip to the south-west at a very slight angle ; and the declivities of the mountain in that direction are those which present the grandest points of scenery. They contain an immense labyrinth of small valleys and ravines, in the mazes of which we should have lost ourselves had we not been accompanied by a local guide. It is in this locality that the rocks assume their wildest and most fantastic appearance. I calculate that these windings extend for a distance of three or four miles at the least ; and the whole length of the Torcal will be about two leagues. In its upper part, there exist veins of laminated peroxide of iron ; and on the slopes we found a great many crystals of carbonate of lime, some of the common rhombohedral type (calcite), while a great majority had a very fibrous structure.

This mountain-chain must have risen from the valley of Antequera ; but its upheaval must have been exceedingly gradual and gentle, as its planes of stratification run perfectly parallel throughout, and we