Chapter XV

Valparaiso — Portillo Pass — Sagacity of mules — Mountain-torrents — Mines, how discovered — Proofs of the gradual elevation of the Cordillera — Effect of snow on rocks — Geological structure of the two main ranges, their distinct origin and upheaval — Great subsidence — Red snow — Winds — Pinnacles of snow — Dry and clear atmosphere — Electricity — Pampas — Zoology of the opposite sides of the Andes — Locusts — Great Bugs — Mendoza — Uspallata Pass — Silicified trees buried as they grew — Incas Bridge — Badness of the passes exaggerated — Cumbre — Casuchas — Valparaiso.