SHE is so ubiquitous, so assimilated, that we sometimes need to be reminded of how strange Bjork really is. So here is a reminder: Bjork is very strange. She is peculiar from the top of her head (flung from side to side in a novel variation on standard headbanging technique) to the soles of her feet (bare and either tip-toeing, skipping or sprinting across the stage). Headlining the Reading Festival last Saturday night, she sported a sparkly pink Chinese dress. Presumably, she had given all those brown woollen jumpers she used to wear back to the jumble sale where she found them. But don't be fooled by the new couture: she still dances and screams like a wild forest toddler who has been driven mad by sudden exposure to Nintendo games.

Rather more interesting, though, is the strangeness of her music, especially as it was arranged tonight. Sounds were thrown into unconventional formations, just as her astonishing voice sparks English vocabulary off an Icelandic accent. Which other song apart from "Isobel" could happily marry a solemn Baroque harpsichord and a jungle beat (thumping tribal drums, not a super- fast club rhythm)? Which song but "Hyper-ballad" would juxtapose a squeaking accordion and a jungle beat (the club rhythm, not the tribal drums)?

It doesn't always work, of course. For ears attuned to music drawn from a mere 19 or 20 influences, say, Bjork's polyphonic sonic collages can sometimes be baffling. But considering that the best British pop groups are choking on beer fumes and stale cigarette smoke, any strangeness at all is such a breath of fresh air that you risk a dose of the bends.

Visually, Ms Gudmundsdottir had come prepared. At the end of her set a crane hauled a gigantic postage stamp, fizzing with sparklers, high above the stage. To follow, a firework display, as dazzling as the music. Bjond belief.

Neil Young closed the festival on Sunday night and made every other group of the day seem like his warm-up acts. And why shouldn't they be? After all, his backing musicians were Pearl Jam, currently America's best-loved band. Not only were they willing to play second fiddle, or second guitar, to the Grandaddy of grunge, they were so excited by the role that they buzzed around him like flies on speed. These youthful high jinks culminated in Mike McCready splintering his guitar, then toppling an amp and a keyboard as an encore. It was an odd piece of time travel, redolent of the film Back to the Future, in which Michael J Fox appears in 1955 and indirectly teaches Chuck Berry how to play a Chuck Berry song. Here was a Sixties rocker backed by Nineties rockers whose destructive behaviour emulated Sixties rockers.

This temporal confusion was given another twist by a track from Young's latest album, Mirrorball (Reprise). "Downtown" has a riff so classic that it could have come from the Sixties, and it reminisces about those hazy days: "Jimi's play- ing in the back room/ Led Zeppelin onstage ... " What is weird about hearing the song is that Young was there in that backroom with those icons. But how many of them are doing some of their very best work now, in the Nineties? Hendrix? Well, no, and neither are any of the others. Young is unique among the stars of his generation, and Pearl Jam's endorsement simply confirms the fact: he is not just their precursor but also their contemporary. Young by name and by nature.

His vocals have often been an Emo Phillips-rivalling whine. Tonight his singing was as powerful as ... well, as powerful as his guitar playing. There was a beautiful solo acoustic section that included "Hey Hey My My", the song which Kurt Cobain - Pearl Jam's arch rival - quoted on his suicide note. The time was out of joint again. Otherwise, this was hammer- and-anvil rock, grizzly- bear rock.

For Young, the genre is not just a game, an amusement, as one senses it is for the Rolling Stones, nor is he marking time between his CD-Rom and his Oratorio. This is his life. He knows where he's going and anyone who gets in his way is asking for some of the same treatment as McCready's guitar got.

The other key point about him is his access to a limitless fount of melodies. He is one of the very few artists who can play guitar solos that last longer than 10 seconds without sending the audience to sleep. He sometimes sends them to a different state of consciousness, though. As "Rocking in the Free World" flew across the field and reverberated off the burger stalls, one fan sighed: "He just takes you higher and higher." Maybe it was just the effect of the fumes that crept from the styrofoam cup-fuelled bonfires, but I was inclined to agree.