The Sierra Nevada is a mountain range in the American West between California's Central Valley and the Great Basin, with its Carson Range spur lying in the state of Nevada. The Sierra Nevada was named by the Spanish adventurer Juan Rodriguez Cabrillo in 1542, its name meaning "snowy mountains" in Spanish. No Spanish explorers visited the Sierra Nevada, and American exploration of the mountain range started in 1827 with Jedediah Smith's crossing into the mountains north of the Yosemite in May of that year. In 1844, John C. Fremont and Kit Carson were the first European-Americans to see Lake Tahoe. The California Gold Rush of 1848 led to the development of mining in the Sierra Nevada as 300,000 gold-seekers came to California from around the world and displaced the Indian tribes. It was not until the 1860s-1890s that the Sierra was thoroughly explored, and the USGS published a set of maps of the Sierra in 1912, ending the era of exploration. The logging of giant sequoia trees and overgrazing by sheep became problematic, laeding to the formation of Sequoia National Park in 1906.