The ground surface is so nearly level that you have no sense of contour. . . . It is not a former lake, although in large part it is a former swamp. Geology characteristically repeats itself around the world and down through time, but---with the possible exceptions of the Chilean Longitudinal Valley and the Dalbandin Trough in Pakistan---the Great Central Valley of California has no counterpart on this planet.
~ John McPhee, Assembling California