материк?

[upthera44.livejournal.com]

Is there a slang word материк that means something like 'the big city' or to the capital?

In a recent film, Комбинат надежда, which takes place in the industrial town Norilsk, they keep saying something like "На материку улетаешь?" which I assume means, "Are you leaving for the big city?" What is this word? Is it slang? In 12 years of speaking Russian I haven't heard it...