Robert Stone's Earth Days begins with a procession of American presidents, going back to Kennedy, speaking publicly about the need to protect Earth's natural resources. It offers a perspective on how many of them made good on their words, which the documentary extends to several major instigators in the early environmental movement.

Robert Stone's Earth Days begins with a procession of American presidents, going back to Kennedy, speaking publicly about the need to protect Earth's natural resources. It offers a perspective on how many of them made good on their words, which the documentary extends to several major instigators in the early environmental movement.

Through archive footage and interviews with participants such as former Interior Secretary Stewart Udall, Earth Day co-founder Pete McCloskey and "hippie astronaut" Rusty Schweickart, Stone chronicles how the release of Rachel Carson's A Silent Spring and other happenings - the dawn of the atomic age, a spike in oil prices, the space program and Jacques Cousteau's oceanographic work - had an impact on environmental awareness.

The story includes several missed opportunities on the conservation side, moments in which the well-meaning didn't know how to temper their message to make it effective. While it presents a fascinating compilation of facts, at times the film displays the same flaw. It's inescapable in Michael Giacchino's score, a manipulative mix of folksy acoustic guitar for the simpler, more natural days of the past and portentous keyboard tones for a rising landscape of power plants.

Stone will introduce Friday's screening.