For Emmeline Summerton, a self-taught social historian whose Instagram account, Lost Canyons LA, has become an addictive source of Los Angeles history and lore, the story of Topanga Canyon is one of improbable survival — a thoroughly wild place less than an hour’s drive from the city’s business center.

W hen wildfires broke out across Los Angeles earlier this month, many publications began to frame the incalculable tragedy through the lens of celebrity news. As flames engulfed t