The second wave of reissues in Led Zeppelin‘s overhaul of their classic catalog pretty much follows the path set by the first: remastered versions of the original albums on one disc, and alternate takes and mixes (along with the occasional rare cut) on the other. The band’s self-titled 1969 debut included live tracks, but all of the others so far — including the new ‘IV’ and ‘Houses of the Holy’ — have basically replicated the original LPs with different versions of the same songs. That doesn’t give fans looking for more obscure Zeppelin tracks much to reach for, but Led Zeppelin weren’t ones to waste much. During the decade in which they recorded their eight albums, very few songs were left unreleased. Only one B-side — 1970's ‘Immigrant Song’ flip, ‘Hey Hey What Can I Do’ — even surfaced during their run. So don’t expect to hear any recently unearthed gems on the remastered deluxe editions of 1971's ’IV’ and 1973's ’Houses of the Holy.’
The story of Earth is an epic filled with crises, catastrophes, and remarkable, repeated change. Earth traces its origin to simple atoms that were created in the big bang, transformed into heavy elements in stellar explosions, and then forged into a planet inside the nebula that gave birth to the solar system. Like many other planets, Earth went through phases of melting, volcanism, and bombardment by asteroids. But only on Earth did events lead to a flourishing biosphere—life. And once life was established, it drove the evolution of our planet in startling new directions.