Metal Underground.com

Led Zeppelin's "Runes" album, Black Sabbath's "Paranoid," Iron Maiden's "The Number of the Beast," and Metallica's "Master of Puppets" - add Mastodon's "Crack the Skye" to that impressive list as one of the classic albums that redefines heavy metal.

I was already a big Mastodon fan, having particularly enjoyed the "Moby Dick"-inspired "Leviathan." "Blood Mountain" took the band a step further instrumentally, but a step back in terms of lyrics.

"Crack the Skye" extends the band's reach past both those impressive discs, and past any other metal act out there today. This is the most lyrically and instrumentally fascinating metal album I've heard in the past decade.

In some ways, "Crack the Skye" zigs where Mastodon's previous efforts zagged. Where "Leviathan" and "Blood Mountain" both began with songs that went from zero to 60 in under a second, "Crack the Skye" opens with "Oblivion," which opens slowly, with a sole guitar being gradually joined by other instruments. There's something nearly symphonic about it. And then Brent Hinds starts to sing, and it's obvious that the previous blueprint has been, if not thrown away, then at least heavily revised. Hinds' voice, usually guttural, now sounds like a more tuneful Ozzy Osbourne.

This is a musical journey in the finest sense of the word. I'm not sure I get the whole story the band has talked about in interviews - something about a paraplegic who travels via astral projection, gets too close to the sun, (which somehow results in him losing the ability to get back to his body until he is somehow sent to czarist Russia and meets Rasputin, who is murdered while attempting to overthrow the czar), but also manages to help the paraplegic fight off the devil and return to his body. That said, you definitely feel the sense of disconnection that the band is aiming for in songs like "Divinations" and "Quintessence."

"Divinations," in particular, has a unique sense of musical adventure, beginning with Hinds on a banjo, before the song heads into more familiar, if still space-y metal territory.

If I had to pick the song that sounds most like "old-school" Mastodon, it'd be "Quintessence," with its high-note riffing and bouts of drum madness, courtesy of Brann Dailor.

When I'd heard that "Crack the Skye" was to be a more melodic effort than Mastodon's previous albums, I was a bit worried that Dailor's drumming would suffer as a result. I needn't have worried — he's still playing some of the most unique patterns in metal, but they are more successfully integrated into the songs than they were in previous releases.

At the album's center, literally, is the four-part epic, "The Czar," which features an amazing variety of fast and slow parts, including some splendidly subtle synth work. I particularly enjoyed a moment about four minutes in, when the band transitioned between the dirge-like opening to a guitar line that is almost danceable.

"The Ghost of Karelia" begins with a classic Mastodon high guitar riff, but is the one song that doesn't quite hit the heights the rest do. It's essential to the journey, but is really just a connecting point between "The Czar" and the title track, "Crack the Skye," which features guest vocals from Scott Kelly of Neurosis.

The 13-minute "The Last Baron" masterfully closes out the album, offering up everything from an almost folky opening, to some wondrous drum and guitar hysterics in the middle, before ending with a bluesy solo.

Producer Brendan O'Brien, who also gave us AC/DC's recent masterpiece "Black Ice," helps the band to create some of the warmest sounds in metal. Drums have just the right amount of echo, and the guitars never completely descend into the cold distortion sound so prevalent in metal these days.

A musical journey that redefines both Mastodon and metal as a whole, "Crack the Skye" stands as a milestone moment in rock.