lava-currents, properly so-called, in the Euganean hills and the Siebengebirge near Bonn;—and at other times the same study describes to us volcanos arranged in single or double lines extending through many hundred leagues in length, these lines being either parallel to the direction of a great chain of mountains, as in Guatimala, in Peru, and in Java, or cutting it transversely or at right angles, as in tropical Mexico. In this land of the Aztecs the fire-emitting trachytic mountains are the only ones which attain the elevation of the lofty region of perpetual snow; they are ranged in the direction of a parallel of latitude, and have probably been raised from a fissure 420 English geographical miles long, traversing the continent from the Pacific to the Atlantic Ocean.
These assemblages of volcanos, whether in rounded groups or in double lines, show in the most conclusive manner that the volcanic agencies do not depend on small or restricted causes, in near proximity to the surface of the earth, but that they are great phænomena of deep-seated origin. The whole of the eastern part of the American continent, which is poor in metals, is, in its present state, without fire-emitting mountains, without masses of trachyte, and perhaps even without basalt containing olivine. All the American volcanos are on the side of the continent which is opposite to Asia, in the chain of the Andes which runs nearly in the direction of a meridian, and extends over a length of 7200 geographical miles.
The whole plateau or high-land of Quito, of which Pichincha, Cotopaxi, and Tunguragua form the summits,
