Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/227

 could not anywhere perceive the slightest distortion. We concurred in opinion that it had been denuded after attaining its high level.

The mountain-chain of which the Torcal forms a part extends in a western direction for about thirty miles. After leaving the plain of Antequera it takes the name of " Sierra del Valle de Abdalagis," ending a little to the west of the place crossed by the Malaga and Cordova Railway, named the " Tajos del Gaitan." In this spot the river Guadalhoree has not only excavated a very deep and narrow ravine, but it has actually pierced through an enormous mass of rock at least 800 feet high, giving a further proof of the highly disintegrate character of the rock. The scenery here is also very wild and grand ; and no traveller who passes through this defile can be wholly free from a feeling of awe and admiration. The colour of the compact limestone in these parts of the chain is white, having little or no admixture of iron. However, this rock is everywhere to be seen superposed upon the Oolite. The Jurassic strata which constitute the mountainous districts to the south and west of Ronda may belong to the same period, as well as those which exist in this neighbourhood, about two miles west of the town, constituting the quarries of St. Telmo, mentioned in Professor Ansted's memoir ; these rocks, though devoid of fossils, have a marked similarity to those which constitute the Tajos del Gaitan. The corroboration of these views, however, must be the result of a careful and conscientious study, which I have not undertaken.

Note. — This paper was accompanied by photographs of Ammonites obtained from the compact limestone of the Sierra del Valle de Abdalagis, and of one from the Sierra de la Chimenea. These Ammonites are all of Jurassic age, and probably from the middle and higher members of that group of rocks. Some of the specimens represented are far too imperfect for identification ; but Mr. Etheridge, to whom they have been submitted, refers four of them to Amm. Achilles, D'Orb. (PI. V. fig. 1), and two others to Amm. per armatus, Sow., one of which closely resembles the var. catena, D'Orb. (fig. 3). The remainder cannot safely be identified. Of the species represented in fig. 2, there are photographs of two ages.

EXPLANATION OF PLATE V.

(Figures about half the natural size.)

Fig. 1. Ammonites Achilles, D'Orb.

2. Ammonites, sp.

3. Ammonites perarmatus, Sow., var. catena, D'Orb.

Discussion.

Prof. Ansted remarked that the condition of the Torcal was similar to that prevailing in many other limestone districts, and was probably due to subaerial denudation.

Mr. W. W. Smyth mentioned that he had lately had an opportunity of examining, at Cadiz, a collection of fossils formed by Mr. Macpherson in that district, which also contained specimens of Ammo-

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