A re-mastered concert featuring folk legends James Taylor and Joni Mitchell is now available for the first time. Amchitka: the 1970 concert that launched Greenpeace captures Mitchell and Taylor and in all their youthful, creative glory. And - holy patchouli! - they duet on a version of Dylan's "Mr. Tambourine Man." I'm quivering in my Birkenstocks!

In all seriousness, though, this is a welcome double-disc dosage of seminal folk-rock from now-classic stars trying to make a political difference during their musical prime. The event's aim was to raise money to send activists to stop U.S. nuclear tests near the Alaskan island of Amchitka, and it was also Greenpeace's first campaign.

Phil Ochs - a protest singer whom the FBI once had a nearly-500-page file on - began the set with the type of tunes occasionally referred to as "finger-pointing songs." Ochs soon passed the baton to James Taylor, just 22 at the time and fresh off the success of his Sweet Baby James album.

The real star of this live set, though, is Joni Mitchell, who was nine months shy of releasing Blue, one of the most acclaimed albums of the rock era. The best moments here are her previews of that material: It's a thrill to hear her say, "This is a new song" and then launch into a classic like "My Old Man." Get a taste of this seminal performance after the jump.

Below is the centerpiece of the set, her ten-minute medley of the life-affirming "Carey" and "Mr. Tambourine Man." Mitchell weaves the dulcimer-jamming joy of the former into the psychedelic existentialism of the latter and the result is transcendent.

Midway through the Dylan cover, she forgets the next verse and invites Taylor onstage to take the next few lines - and they continue harmonizing when she gets her lyrical bearings back. Occasionally his down-home country croon jars next to her crystal-clear high notes, but overall, it's hard not to get caught up in the impromptu beauty of the duet.

The concert raised enough money to send eleven peace activists by boat to protest the nuclear testing. The mission didn't succeed, but it did christen the Greenpeace organization, which of course has become one of the leading non-profit environmental protection orgs in the world.