ALEXANDER VON HUMBOLDT AS A PIONEER OF WESTERN NORTH AMERICAN TECTONICS

Alexander von Humboldt went to Mexico in 1803 for less than a year and returned to Europe via Washington where he visited his friend President Thomas Jefferson. While in Mexico, he put together a physical geographical map of the western United States and Mexico, from ~ 16° to ~ 42° N latitude. To draw this map, Humboldt was given an opportunity by the Viceroy Jose de Hirriguay to study all documents kept in the archives of Mexico City. Humboldt also did field work in southern Mexico, constructing hypsometric E-W profiles across Mexico with some geological observations thrown in. He was particularly impressed by the great breadth of the highland, which he followed all the way into Utah using the available documentation. In the future states of Utah, Arizona, New Mexico, and Colorado, Humboldt noted the existence of many other highlands of much smaller size that trended orthogonally with respect to the main N-S mountain axis. He interpreted all highlands as uplift caused by magmatism on the basis of his experience in the Andes. This agreed with earlier ideas of Athanasius Kircher and Compte du Buffon. Humboldt left a copy of his map in Washington with the secretary of war, Mr. Madison. This map formed the basis of all future exploration plans in the southwestern US, from Zebolon Montgomery Pike to Major William H Emery. Humboldt’s ideas on the tectonics of the western US influenced those who went to the field to inspect the geology in the SW United States until, and including, the Pacific Railroad Surveys in the 1850’s. Jules Marcou interpreted the entire cross section from the Mississippi to the Pacific ocean very much in a Humboldtian sense. Humboldt himself remained interested in the tectonics of the western US until his death in 1859. For example, when John Strong Newburry accompanied the Ives expedition, he had received questions from Humboldt concerning details of the areas to be explored. The Americans paid their debt to Humboldt by naming many physical features of the Western US after him.