June 5.—We travelled down the valley about east. At about one and a half mile we passed a very curious-looking place, where a small stream came out of a valley to the northward and westward, and spread itself over a flat table-rock, soft and calcareous. It poured over this rock in a sort of horse-shoe cataract, and then spread over an apparently convex surface of this same soft rock, about two hundred and fifty yards wide, crossing the valley down which we were travelling. This rock sounded hollow under the feet of the mules, and I feared we should break through at every instant. I am confident it was but a thin crust; and, indeed, after crossing it, we observed a clear stream of water issuing from beneath it, and flowing into the road on the farther side. We saw another such place a little lower down, only the stream tumbled, in a variety of colored streaks, principally white, like salt, over the metallic-looking rock, into the rivulet below. I presume there must have been some volcano near here, and that this rock is lava, for it had all the appearance of having once been liquid.
Lt. Gibbon del.
Wagner & McGuigan's Lith. Phila.
HACIENDA DE MAYOC.
Pl. 3.
Lt. Gibbon del.
Wagner & McGuigan's Lith. Phila.