Crossover

Two floors, one pit

Half skateboard and half amplifier stack, crossover thrash was welded together in the middle of the 1980s by kids who went to hardcore shows and thrash shows in the same week and refused to choose, then bolted the palm muted thrash riff to the hardcore sprint and drove both through the crash barrier at the bottom of the ramp. The drums lean on the d-beat and the skank beat. The singer shouts. Nobody solos for long.

What separates it from its parents is the trade each side made. Hardcore gave up the right to stay loose and took in riffs cut with thrash precision and the mosh part, a slowed breakdown built to set a whole room in motion. Thrash gave up the long song and took in hardcore's raw attitude, its humour and its lyrics about real life. Picture a skateboard deck bolted onto a lathe bed: it still rolls, it still grinds, and now it weighs enough to take a wall down.

Crossover from Houston to Venice

The map has three corners and a van. Formed in Houston in May 1982, the band that called itself Dirty Rotten Imbeciles moved to San Francisco the next year, lived in its van, ate at soup kitchens between gigs and in 1987 put out the Metal Blade album whose title, Crossover, gave the whole style its name. Venice, California, sent Suicidal Tendencies and Excel. Santa Monica sent Cryptic Slaughter, started by teenagers aged 14, 15 and 17.

New York built the heaviest furnace, with Cro-Mags, Leeway and Nuclear Assault all working the seam, while Raleigh in North Carolina sent Corrosion of Conformity. The confusion starts with a single word. In the early 1980s punks used thrash for fast hardcore itself, which is why the fastest punk strain later took the name thrashcore, a hardcore style with no metal in it. Crossover stands on the metal side of that fence, under thrash metal.

The trade ran on into the next decade. Prong and Excel slowed the riff and made it swing, one of the roads into groove metal, and the mosh part fed straight into early metalcore. The crossover revival came in the 2000s. Municipal Waste and later Iron Reagan came out of Richmond, Virginia, Power Trip dragged the sound back into the pit from Texas, and the ramp is still open.

Where to start

Eight crossover albums, most of them short, all of them loud, every one built to be worn down to the groove.

• Suicidal Tendencies Suicidal Tendencies Frontier, 1983

  Produced by Glen E. Friedman, who also shot the cover, with "Institutionalized" among the first videos of its kind on MTV and sales few hardcore albums matched.

• Corrosion of Conformity Animosity Death Records, 1985

  Twenty six minutes recorded between Los Angeles and Raleigh under a Pushead cover, with songs later covered by Metallica, Mr. Bungle and Iron Monkey.

• Cro-Mags The Age of Quarrel Profile, 1986

  New York hardcore welded to the weight of Motörhead and Black Sabbath, in Revolver's reading, under a title taken from the Kali Yuga of Hindu scripture.

• Cryptic Slaughter Convicted Death/Metal Blade, 1986

  Made by Santa Monica teenagers, more than 25,000 copies sold in its first year, and one of the fastest records the hardcore floor had heard.

• D.R.I. Crossover Metal Blade, 1987

  The record that named the style, with the Houston band's hardcore now carrying a full metal weight in every riff.

• Excel Split Image Suicidal/Caroline, 1987

  The debut of the Venice band formed by Dan Clements and Adam Siegel, raised in the same West Side scene as Suicidal Tendencies.

• Municipal Waste Hazardous Mutation Earache, 2005

  Short bursts instead of long songs, an Ed Repka cover of mutants chasing a red dump truck, and the band's first record for Earache.

• Iron Reagan The Tyranny of Will Relapse, 2014

  Tony Foresta and Phil Hall of Municipal Waste in a second Richmond engine, debuting at number 22 on the US Heatseekers chart.