Page:Appleton's Guide to Mexico.djvu/256

228 of scoriaceous basalt, and looks like the slag of a furnace.

The rocks of Jorullo, however, are neither uniform in texture nor composition. They vary in color from black and red to gray and grayish white. Bluish basalt containing olivine occurs near the bottom of the crater, and whitish-gray trachyte forms the greater part of it. The latter rock is traversed with a few small veins of sulphur.

The tourist may descend to the bottom of the mouth of the volcano, which is about 500 feet below the summit. The walls slant rapidly and are covered with an enormous mass of talus, containing many angular fragments of red and black rocks. Shocks of earthquake are often felt in the environs of Jorullo, extending sometimes as far as Morelia, 60 miles distant.

A recent earthquake (in March, 1883) was perceptible at Ario for the space of two minutes, and cracks were formed in the ground at a point ten miles off.

Although no eruption has taken place for upward of a hundred years, this volcano is still in a semi-active state, as shown by the heat of the crater-walls, the emission of sulphurous gas and aqueous vapor, and the frequency of earthquakes. Another stream of lava might flow out of Jorullo at any time.

The view from the summit next demands attention. It is very extensive. The eye follows the contour of the Sierra Madre to the westward for more than 100 miles, until the lofty volcano of Colima, capped with snow, bounds the horizon. The picturesque mountain, La Estancia de los Padres, is very conspicuous, and also the grassy plain in front of it, having a breadth of forty-five miles. On the south the country is much broken in outline, and to the eastward the observer may trace the undulating surface of the table-land. Looking northerly, one sees the sugar-cane fields and banana-groves near Tejamanil, whose bright