McHarg classified seven land types worthy of preservation for services and hazard avoidance

Evidence

On the one hand, nature did important work – providing water, air, wildlife habitat, and agricultural produce. On the other hand, nature threatened human health and well-being – creating floods, forest fires, landslides, and hurricanes. McHarg concluded that a sound open-space plan would ensure the continued operation of beneficial “natural processes” while protecting people from natural hazards. Relying on both common sense and ecological science, McHarg then identified seven types of land especially worthy of preservation. — Adam Rome, The Bulldozer in the Countryside, 705