Holy shit! Never have I seen so much crap in a movie: figuratively, metaphorically and literally.

At 5 hours and 50 minutes Matthew Barney’s River of Fundament, which recently played as part of NZ Festival at Wellington’s Embassy Theatre, is a film of excess in every sense.

It’s an opera: grandiose and religiose; structured around music with big symbolic sculptural set pieces, and full of memorable exquisiteness. Yet its excess is also rooted in endurance performance art. It’s as if the mind of a performance artist (of which Barney himself is one) has been epically visualised: shitting, fornicating and spouting texts, with flatulency. We are wowed, we are stupefied, we are disgusted, and - ultimately I found - rendered numbed and occasionally unconscious. I went home and took a shower. I need another one.  

A fundament may be defined as the foundation of things, but also the buttocks and anus. At its dazzling occasional best the film allows us to meditate on how we all come from this base place - that value is in the eye of the beholder. All is turning to shit, especially America. This is not a film of hope or healing, but of forging new forms from the rot of what remains. It’s just a pity that Barney never allows new life to grow from the epic fertilizing shapes he throws.

The film is loosely based on Norman Mailer’s much derided yet admired Ancient Evenings, delving into religious notions of sex, death and reincarnation through the stories of the ancient Egyptian Gods around the 12th century BC.  

In Mailer’s carnal take on Egyptian cosmology the dead must pass through a river of faeces. In River of Fundament the Egyptian Gods are the various forms of the reincarnated Norman and a series of classic American cars, destroyed and remade. The film is structured around Mailer’s wake, set in an astonishing recreation of his apartment, revealed to be floating on a barge down the river to Manhattan. This is just one of the many majestic things that make this a film you may feel the need to endure.

As a ‘film event’ (a term whose fatuousness should have been a warning) organized by Adam Art Gallery with the Festival you won’t find it on Netflix.  But an eight-minute teaser, stripping the film back to all its cinematographic and performative gorgeousness is here. And an exhibition of Barney’s Drawing Restraints performance works 1988-2015 is beautifully presented at the gallery. We miss the opportunity unfortunately to see the film in concert with an exhibition of its sculptures, as has been presented elsewhere (here’s a walkthrough) including at Tasmania’s MONA.

Mailer’s book is famed for its weirdness. Barney embraces it. “Crude thoughts and fierce acts” is Ancient Evenings first line. With his hero’s passing in 2007, Barney has taken on Mailer’s relationship to society and made it his own, at our indulgence.

River of Fundament does have the decency to ensure those not in for a longish haul leave before the opening title appears. For those who stay there is much to savour as well as abhor, it’s just a pity that it’s such a mess. Structurally Barney continually frustrates. Much doesn’t sustain, shapes are cast but then stunted. There are large sections seen through a documentary eye that show promise in the way they symbolise America’s decay – an extravaganza with a Chrysler in a showroom in California, a musical crime drama played out on boats and a barge on the industrial waterways of Detroit, counterpointed by sublime American landscape. Yet there’s always the frustration that you’re overlooking these events, rather than attending them.

Most memorable are the scenes with guests at Mailer’s wake in the first two Acts. As the evening progresses and musicians arrive the real turns surreal musical. With fine actors and musicians in abundance the prattle of socialite and literati morph comically into expressive experimental pieces for voice, with cameos from the likes of Salman Rushdie and Debbie Harry. Like those cameos, River of Fundament has the feeling of a film made during the 1980s. It has that decade’s grandiose New York ‘80s swagger (and the heyday of the likes of Peter Greenaway and Derek Jarman comes to mind). Is this really where America is at in 2014, or where it has been?  

By Act Three, four hours in, the party guests have pretty much gone, leaving the Egyptian Pharoah and Gods in Mailer’s house to go at it. And do they ever. It’s a particularly testing final feature, with yet more promising sequences involving gilded cars, sex and violence that prove difficult to follow.

The music in this final part is particularly lulling, but ultimately plain annoying. On paper there is a gorgeous fusion of Walt Whitman, strings, choral singers and Native American song, chants and drums. In real time the lullaby proves nauseous.    

Somewhere in there are the trailings of a great film about America, one thoughtfully composed around the hard percussive sounds of the automobile industry and the wind pipes of the human body. Barney spectacularly mixes modes and media, but it remains extravagant experiment rather than satisfying form next to the work of filmmakers who have previously paved this way. Vast tracts of this film could have been cut for the better.  

A written synopses for the film is provided, but it’s hard to get a handle on. You wonder whether Barney is really that interested in us being invested in his narratives at all. Rather, River of Fundament’s reward is a rich banquet of cultural amalgam across music, performance and object. A film for artists to learn from rather than enjoy.  

At the time Ancient Evenings was set the Egyptians were themselves groundbreaking in their metalwork and fusions of metals (alloys). The process of forging and making sculpture is a constant in the film, and transformation of base materials and metals to gold. The American car industry was built on alloys. The American dream is well and truly over.

Metallurgy is the film’s great fundament. A testing of both mettle and metal, you could say. Yet you sense that its Barney’s own incredible drive to experiment in new ground, making a film based around the extension of both sculpture and performance art, are part of its ultimate undoing.

Five films made up Matthew Barney’s Cremaster Cycle, made between 1994 and 2003. They saw him acclaimed as one of the great American artists of our time (and are these days up on Youtube). River of Fundament however sees him lost in his own grand forest of an art trying to find a way through.  

Some might pose that criticism of the mess of Barney’s film might be simply an ode to Norman Mailer’s own. No excuse. Such tortured man-alone heroics seem rather old hat right now. The New York artworld’s last great dump.

River of Fundament simply didn’t move or change me. I see little more reason to revere it anymore than the expensive bloated failures of our mainstream film directors, with their popcorn excesses of sex and violence amongst the new Gods.

We ask our artists to risk failure to push through. None could accuse Barney of not doing that. Further, for Adam Art Gallery and its remit for critical thinking around art this film’s presentation was a smart move. NZ Festival is also to be congratulated for having the nerve to present it.

Yet I question whether a seven-hour screening session is the best way to engage with River of Fundament. It contains many astonishing things worth browsing one day when all this exclusive endurance screening nonsense is over. Just don’t expect to like it.

• Drawing Restraint, Matthew Barney, Adam Art Gallery, until 24 April