What is The Caldera

A caldera is a large depression formed when a volcano erupts and collapses. It usually leaves a lake at the top of a mountain. In Cook's novel, the Caldera is a notable feature in the landscape of the area around Middle Post, later named "Madeline's Valley" by Agnes. The Community's final instruction from the Rangers is to summit the Caldera, which is a long and dangerous trek. On this journey, Glen dies when he falls during the climb and injures his body.