It’s just over 50 years since the passing of the Wilderness Act in the United States. The environmentalist and writer Gary Ferguson, who was eight years old then, recalls a time when “nature was on the run”, when the ponds and channels he and his brother swam in were “thick with the tang of dioxins”. In Big Sky Journal, he considers what’s been achieved since, and  celebrates Americans’ “long, dizzy love affair with unfettered landscapes”.