The mission oases of arid northern Mexico: a water technology that outlived the missions by two and a half centuries

In the deserts of Baja California and Sonora the Jesuit missions laid a system of water retention and conduction onto relict wetlands already there, and planted them in layered orchards. The missions went in 1767; the plots did not. Ranchero families still work up to forty-two species around missionary olive and grape, and Tohono O'odham plots at Quitovac hold up to a hundred and thirty-nine. The same colonisation destroyed most of the peoples of the region, and the scholarship records both.