One of the great blog projects for the geologically minded reader is "Up and Down California," which serializes the government-sponsored Whitney Survey exactly 150 years later. The survey was a remarkable four-year-long expedition led by Josiah Whitney (eponym of Mount Whitney), mapping and describing the mines and geology of the new state of California.
In yesterday's entry (that is, on 13 August 1862), Whitney describes the state of the Sacramento River after two mammoth disturbances: first was the widespread hydraulic mining of the Sierra Nevada gold country, which stripped whole landscapes of their forests and soils; second was the terrible wet winter of 186162, when six solid weeks of "atmospheric river" rain redeposited much of the Sierra's loose sediment and massively flooded the Central Valley. "Indeed," Whitney writes, "the water is still over a part of it." He describes drastic changes in the rivers feeding into the Valley, changes that are still felt today.
The situation of California 150 years ago was one of the first, if not the first, instances of human activity pervasively altering a region. Today that premonitory example has been magnified to the entire globe, as the atmosphere itself is rushing toward a doubling of its carbon-dioxide levels and the world's temperature steadily rises. That situation, in which the human race finds itself at the wheel of the world, is called the Anthropocene age. Josiah Whitney was a scientific witness to one of its first stirrings.