As California’s economy skyrocketed during the 20th century, its land headed in the opposite direction. A booming agricultural industry in the state’s San Joaquin Valley, combined with punishing droughts, led to the over-extraction of water from aquifers. Like huge, empty water bottles, the aquifers crumpled, a phenomenon geologists call subsidence. By 1970, the land had sunk as much as 28 feet in the valley, with less-than-ideal consequences for the humans and infrastructure above the aquifers.