Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/297

Rh Peak sloping down on the eastern, western, and northern sides, to the sea. Towards the south, or more properly the S.S.W. the mountains are nearly perpendicular, and, though broken into ridges and occasionally separated by deep ravines that are cut transversely as well as longitudinally, there are none of those plains nor that gradual declination of strata that the south-eastern and north-western sides of the island exhibit.

From the Barranco Seco, in the neighbourhood of Santa Cruz, to the northerly point called Punta del Hidalgo, a series of steep and abrupt mountains form headlands to the sea, separated from the central chain by the valley of Laguna; these mountains are rugged and peaked, drawn up, if the term may be used, in a column, and are divided by deep ravines. The sides of these mountains are steep, being in many places cut nearly perpendicular to the horizon, and are all composed of lava generally of the basaltic formation, mixed with beds of tufa and pumice. From Hidalgo point to that of Teno, the most westerly point of the island, the strata vary from beds of pumice and decomposed lava and ash, which form the plains of Laguna Ticaronte and Songal, to streams and currents and headlands of lava, similar to those of the Barranco Hundo, San Ursula, Las Horcas, and Las Guanchas. The slope from the central chain is here gradual, intersected by ravines and streams of lava. The soil famed for its fertility and which produces the Teneriffe wine, is composed of lava and ash in a state of decomposition. Headlands, some of them from two to three hundred feet in height, project into the sea between San Ursula and Orotava, forming perpendicular cliffs. At the western extremity of the island from Punta di Teno to Puerto de los Christianos, the strata rise in a broken ridge to the Peak, the land ascending gradually from Punta de Teno by a chain of small peaked hills; the