Many bands sing about generic subjects: love, hate, friendship, sorrow, issues of life and death. Not so Mastodon. The Atlanta quartet arrive in Glasgow for the second time in seven months to scream their hearts out about black matter, astral travel and Tsarist Russia, as they continue to tour in support of the highly-acclaimed Crack The Skye.

A complicated album both thematically and technically, the band insist on playing Crack The Skye in its entirety every night on their present tour, because, as guitarist Bill Kelliher says, "it would be weird to leave a song out." Mastodon, though, have been touring the album since its release in March last year, which goes some way to explaining why, under the dim lights of the Barrowlands Ballroom, they look tired, distant and unengaged as their seemingly ceaseless touring schedule starts to get the better of them.

Even if they look lethargic, they don't sound it: the music is loud and delivered with scientific rigour, which is apt given the band's astrological fixation. Arriving on stage to a barrage of synth-produced noise, they promptly rip into opener ‘Oblivion’, causing a large portion of the audience to erupt into a sea of raised fists and swaying bodies, with crowd-surfers rolling like logs over the heads of those below them, much to the displeasure of disgruntled security staff.

A large screen looms behind the band, providing stunning, if bizarre visuals—spirits, wizards and all manner of other weird images—that compensate for Mastodon's sheer inertia: they are depressingly boring to watch. Barely moving on stage and saying nothing between songs—which to some degree adds to their mystique—Mastodon create a sterile atmosphere, and look like a band just going through the motions.

But a Friday night crowd in Glasgow couldn’t care less, and as the band return to the stage for an encore having concluded Crack The Skye, they are greeted with some of the biggest cheers of the evening as they blast out a selection of songs culled from their back-catalogue; the wildly titled ‘Aqua Dementia’, ‘Mother Puncher’ and closer ‘March Of The Fire Ants’.

Yet whilst there is no doubt that the songs themselves are of epic quality, a live setting demands more than the mere mechanical reproduction of song after song; it demands interaction, communication, emotion—all of which are absent tonight. Mastodon may have been described by Rolling Stone as "kings of the current metal scene", but they haven't earned their crown in Glasgow.