rising or have recently risen. The reason of this is, that an upward bend in a stratum is resisted only by the weight of the stratum itself, while a downward bend is resisted by the pressure on the strata below ; so that an upward bend is more likely than a downward one to become great enough to produce fracture.
3. On Some Points in the Geology of the Neighbourhood of Malaga. By Don M. be Orueba.
(Communicated by Sir. E. I. Murchison, Bart. F.R.S., F.G.S.);
[Plate V.]
Much remains to be done in the investigation of the geological structure of Spain. The Spanish geologists have principally described in a general manner the mineral character of the soil in various districts, but they have not paid sufficient attention to the order of superposition and the character of the fossils, and few foreign men of science have made this country the subject of their investigations. For this reason, what we know at present about the formations of the province of Malaga is principally owing to the able memoir and excellent map of M. Verneuil. However, as I believe this gentleman did not travel in the northern part of this district, he has not given any particular description of many geological formations which, by their order of superposition, mineral composition, and the character of their fossils, might be of great help in ascertaining the place in the geological scale of the analogous strata which exist in other localities of the province, but which do not present so many interesting data and facilities for study. Although I am only acquainted by reference with the opinions of this gentleman (possessing only the map he published in conjunction with M. E. Collomb), I believe that he dwelt principally on the Tertiary formations in this vicinity, and, above all, on those on which the city of Malaga is built. I think that he was the first person that ever described them, publishing also a list of several shells, which he collected at the " Tejares" (clay -pits in the suburbs of this city). Professor Ansted also wrote a very valuable article on the Geology of Malaga, which appeared in the ' Quarterly Journal of the Geological Society ' for 1859*. He also paid a deserved attention to the " Tejares " clays, which are no doubt of the greatest interest, and described several formations in this neighbourhood, particularly those lying on the eastern side of the town ; but I feel rather surprised to see that, while treating on the metamorphic rocks, he does not mention the plutonic, which are also found about here, mentioning only the serpentine of the Sierra de Meijas, and not saying one word about the greenstone (diorite), which is very abundant in several parts of the province, especially in this locality, and which may have been the cause of
- Vol. xv. p. 585.
