About a year before "Smells Like Teen Spirit" topped the Billboard Modern Rock Tracks chart in 1991, Kurt Cobain was holed up in a North Portland recording studio, lending despondent backup vocals to the first official recording of guitarist Dylan Carlson's plodding march of a band, Earth.

But even with Cobain, Earth was no Nirvana. Where Nirvana shaped a hit and a rock renaissance, Earth measured an overdose. Carlson wrote songs without regard for popular music, or its underground, with his bleak and massively overdriven guitar riffs taking the place of lead vocals; Tony Iommi was his Sonic Youth. Carlson's songs were lessons in length, repetition, and guitar-god downstroke, enabled by then-bassist Joe Preston's obedient drum machine.

Audio engineer Mike Lastra, of Smegma Studios, describes a "magic vibe" when Earth drove down from Seattle to roll tape: "I was like, 'Woah,'" he laughs. "And I did think it was sort of a prototype sound." Three songs from the eight-track recording were released on Sub Pop in 1991 as Extra-Capsular Extraction, an EP later coveted by Cobain completists. It was actually deleted from the label's catalog for a time after grunge flatlined. But in recent years, one type of person in particular has found merit in the slow crush of all things Earth: The patient metalhead, newly enlightened to Carlson's spacious guitar tone via the similar craft of popular drone act Sunn O))).

One song from the Portland session, the 18-minute "Ouroboros Is Broken," was re-recorded for 2007's Hibernaculum, released on Southern Lord with accessibility in mind. Carlson, the only remaining original member and survivor of an eight-year recording hiatus, has traded sheer distortion for organic licks and clean, empty space. Earth's forthcoming CD (due out in February) shares a similarity to the rescued American Indian music driving Tomahawk's recent Anonymous CD. Songs like "Omens and Portents I: The Driver" and "Miami Morning Coming Down II (Shine)" are light, psychedelic free falls, pushing Earth a little further from its heavy Northwest past.