1769-1859

German scientist-explorer considered by many the father of geophysics. His explorations in the Americas include navigating the length of the Orinoco, studying Pacific coastal currents, and setting a world record by climbing Chimorazo volcano at 19,279 feet (5,876 m). He was the first to link mountain sickness with oxygen deficiency, and introduced isobars and isotherms for weather maps. Humboldt also related geographical conditions to animal and vegetation distribution, studied global temperature and pressure variations, and discovered that Earth's magnetic field decreases from the poles to the equator.