There's a toothgrinding intensity to the opening track on Earthly Delights, a dainty little number by the name of 'Sound Guardians'. It's a thudding, controlled explosion of iron-edged melody and percussion that seems to increase in volume and ferocity through the course of its four minutes and 52 seconds such is the war-like violence of its assault; it's like, as per Lightning Bolt's usual modus operandi, they're trying to psych us all out by casting down hellfire and thunder into our ears. Granted, it feels slightly more standard than previous 'Bolt works, but that's only because of some mild concession to structure where they play one cataclysm of a riff and then replace it with the same riff, only heavier. It sounds like the music they play on the boat over the river Styx: you're going to hell, might as well get used to it.

And it's the same intensity that's threaded through the album, one borne of the duo's desire to not simply shock, but to unsettle and worry. Ideas are alighted upon and then tossed away like so much ephemera, a tactic that's laudable in theory but which results in an album that's hard to really love but easy to appreciate. You can love what Lightning Bolt make you feel – the swell of 'Colossus' is an elixir of power, 'Rain On Lake I'm Swimming In' is a time-travel capsule back to your youth, when things were simple and colourful – but Earthly Delights, as with all of their oeuvre, is a flyer for their live shows. And that's no bad thing.

The truth is, after listening to Earthly Pleasures for about a month it's still a weirdly shifting, morphing beast of a record that utterly resists definition. There's the towering 'Sound Guardians', of course, and 'Colossus', which could be categorised as stoner rock if the weed in question is some serious weapons-grade shit, dusted with a handful of hallucinatory chemicals and smoked in a dark room where executions once took place. But 'Flooded Chamber' is an aural nightmare, shrill and pinching and full of ripe hot madness. It feels like the voodoo call of some beheaded southern god beaten on a thousand drums and sliced out of raw flesh, while 'SOS' is simply brutality of sound.

There are, of course, heavier and weirder bands than Lightning Bolt, but it's those screams of sound on 'Flooded Chamber' and the galactic swirl of 'Rain On Lake I'm Swimming In', which is bedded by chattering ghosts desperate for attention, that make this record so baffling. Midway through the 12-minute 'Transmissionary' the earthquake guitars return, a welcome reintroduction after 'SOS'' schizophrenia, and it becomes evident that as fun as it is being fucked up and freaked out by a band, sometimes the most potent part of their arsenal is when they lock down a groove and crank it to glorious repetition. That might seem like anathema to the whole idea of Lightning Bolt, but considering 'Transmissionary' is a post-metal masterpiece in controlled violence there's evidence to back this argument up. As with 'Funny Farm' and 'Sound Guardians', the rough edges are still very much integral, but they're marshalled by a coherence of ideas and focus that, rather than diluting their appeal lasers it in to create something powerfully new. It speaks volumes that you could, theoretically, dance to 'Funny Farm' and enjoy all its unhinged pleasures and needle-thin thread of sanity with limbs a-flailing, maybe even in public. Maybe.

'The Sublime Freak' is a collage of terror, an unholy Frankenstein's monster that feels more like an incantation than a song. It's one of those moments, like 'Flooded Chamber', where Lightning Bolt seem to fall in love more with the idea of themselves than the actual practice: it's overlong and meanders noisily and will only be loved by the most contrary of buggers.

But the acid test of Earthly Delights is, of course, whether it sounds like any other band whatsoever. And it doesn't. It's thoroughly imperfect and makes a virtue of its messiness, proclaiming chaos the true victor, but sometimes, through the blitz, transformative and glorious in its flaws.