WOODSTOCK Mud. More mud. Fire.

No, that's not a four-word summation of the early evolution of humans — or a chortle-accented quip from a vintage episode of MTV's "Beavis and Butt-Head." But mud was inextricably a key ingredient at the rain-soaked 1969 and 1994 editions of the legendary Woodstock festival, which were held 55 and 30 years ago this month, respectively. And multiple fires were set by rioting attendees at the event's violent third and final iteration on a late-July weekend in 1999.

Beyond the elements and their shared name of Woodstock, the three festivals are notable for the alternately dispensable and generation-defining music they presented, for the hundreds of thousands of young fans they attracted (many without tickets) and as gauges of both how long-lasting and how fickle pop culture can be. Billed as "three days of peace and music," the exceedingly well-documented 1969 Woodstock was poorly organized and ineptly executed (a template, alas, for the two editions that followed). It had almost no infrastructure of any kind, became a muddy mess following torrential downpours and stretched to four days because of the lengthy rain delays.

But the nearly half-millionstrong audience and the performers — including Jimi Hendrix, Janis Joplin and the Who — rose above the elements, as was vividly documented in the Oscar-winning 1970 documentary film "Woodstock." The mass communal spirit created during that weekend, fueled by a peace, love, "we-are-one" hippie ethos.