The band name doesn't inspire confidence. Nor does the warlock-strewn album cover. Nor the fact that Crack the Skye is the last of a four-album cycle about Earth's elements. But before you sneer, "Hello, Cleveland," listen to Mastodon's thunderous, disciplined and expansive brand of metal. There are plenty of bass-drum carpet-bombings, and "The Czar," a four-part ode to Rasputin O.K., go ahead: "Hello, Cleveland!" has all the whiplash rhythm shifts of vintage Metallica. But the album also has nods to European folk, free jazz and prog rock, and as produced by Brendan O'Brien (Bruce Springsteen, Pearl Jam), it fronts a brawny sound that doesn't overwhelm the clarity of individual notes. Chuckle at lyrics about "the space-time paradigm" if you must, but the ambition and tenacity of Mastodon's music makes Crack the Skye sonically unforgettable.