thousand streams to swell the Orinoco, terminates in the
beautiful mountains of Caracas; the central range culminates in the
volcanic Tolima,[59] but is soon lost in the Caribbean Sea; the western
chain turns to the left, humbling itself as it threads the narrow
isthmus, and expands into the level table-land of Mexico. You may cross
Mexico from ocean to ocean in a carriage, but no wheeled vehicle ever
crossed South America.

[Footnote 58: This lake is the largest fresh-water accumulation in South
America. It has diminished within the historic period. Its surface is
12,795 feet above the Pacific, or higher than the highest peaks of the
Pyrenees.]

[Footnote 59: This is the loftiest summit of the Andes in the northern
hemisphere, being 18,200 feet. It is also remarkable for being situated
farther from the sea (120 miles) than any other active volcano.]

[Illustration: Profiles of Ecuadorian Volcanoes

10,000 ft. Chimborazo.

10,000 ft. Cotopaxi.

10,000 ft. Caraguairazo.

10,000 ft. Pichincha.

]

We will now speak more particularly of the Andes of the equator. The
mountain chain is built up of granite, gneissoid, and schistose rocks,
often in vertical position, and capped with trachyte and porphyry.[60]
Large masses of _solid_ rock are rarely seen; every thing is cracked,
calcined, or triturated. While in Bolivia the Eastern Cordillera shows a
succession of sharp, ragged peaks, in contrast with the conical summits
of the Cordillera of the coast, there is no such distinction in the
Andes of the equator.[61] The Eastern Cordillera has a greater mean
height, and it displays more volcanic activity. Twenty volcanic
mountains surround the valley, of which twelve are in the oriental
chain. Three of the twenty are now active (Cotopaxi, Sangai, and
Pichincha), and five others are known to have erupted since the Conquest
(Chiles, Imbabura, Guamani, Tunguragua, and Quirotoa). The truncated
cone of Cotopaxi, the jagged, Alpine crest of ruined Altar, and the dome
of Chimborazo, are the representative forms of the volcanic summits. The
extinct volcanoes usually have double domes or peaks, while the active
peaks are slender cones. Antisana and Cayambi are fashioned after
Chimborazo, though the latter is table-topped rather than convex;
Caraguairazo, Quirotoa, Iliniza, Sincholagua, Ruminagui, and Corazon,
resemble Altar; Tunguragua, Sangai, Llanganati, Cotocachi, Chiles, and
Imbabura, imitate Cotopaxi; Pichincha, Atacatzo,