Free The Long War by Terry Pratchett, Stephen Baxter

How they lived out there depended on preference, education and instinct. Some dashed back and forth between the Datum and the Low Earths, looking for a little more room, a way to make a little more money. Some, like Helen’s family the Greens, had gone trekking out into the stepwise wilderness and had begun to build new communities: the story of colonial-era America, rerun across an infinite frontier. And some just wandered off, helping themselves to the inexhaustible riches of the Long Earth: Thomas’s combers.
    All of which was fine, until the day you needed root-canal dentistry. Or your e-book reader broke down. Or you worried whether your kids were ever going to learn anything more than how to plough a field or trap a rabbit. Or you got sick of the mosquitoes. Or, damn it, you just wanted to go shopping . Some people drifted back to the Datum, or the crowded Low Earths.
    Valhalla was another response: a brand-new city growing out in the High Meggers, the remote Long Earth, but deriving from Long Earth lifestyles: that is, supported by combers, not farmers. There had been precursors in human history, across Datum Earth. Given time and a rich environment, hunter-gatherer populations could achieve huge feats, and develop complex societies. At Watson Brake, Louisiana, five thousand years in the past, nomadic Native American hunter-gatherers had constructed major earthwork complexes. Valhalla had just taken this to a new, modern, more consciously designed level.
    As it happened, the theory of the city was the first topic Jacques Montecute, the school’s headmaster, chose to talk about when he brought Dan and his family into his office for an introductory chat.
    ‘The central ethos of Valhalla is balance,’ Montecute said.
    Aged about thirty, slender, slightly severe, he had an accent that Joshua might have pegged as French, but with a naggingly familiar overlay. His name rang a bell too. Montecute . . .
    There was one other child here, aside from Dan, a dark, unsmiling girl of about fifteen, called Roberta Golding.
    ‘Most of our adult citizens chose to leave the old world, to leave the old ways behind. They want some of what a city can give, but they didn’t come out into the Long Earth to break their backs farming, or to live in some slum suburb, in order to serve that city’s needs. But here we are, maintaining city life without all that.’ He smiled encouragingly at Dan. ‘Can you see how we make a living, without farmers to grow our food for us?’
    Dan shrugged his slim shoulders. ‘Maybe you’re all robbers.’
    Helen sighed.
    Roberta Golding spoke for the first time since being introduced. ‘Valhalla is a city supported by combers. Hunter-gatherers. The logic is elementary. Intensive farming can support orders of magnitude more people per acre than hunting and gathering. On a single world a comber community, even if natural resources are rich, would necessarily be spread out, diffuse; the concentration of population needed to sustain a city would be impossible. Here, it is sufficient for the combers to be spread out, not geographically, but over many stepwise Earths – over a hundred parallel Valhallas, left wild for the hunting.’ She made a sandwich of her hands, pressing. ‘The city is the product of a layer of worlds, each lightly harvested, rather than the product of a single intensively farmed world. This is intensive gathering : a uniquely post-stepping urban solution.’
    Joshua thought the kid spoke like a textbook.
    ‘You’ve been reading up,’ said Helen, as if accusing her of cheating.
    ‘Very good, Roberta,’ said Montecute. ‘I mean, it also helps that we live in such a rich location, geographically, by the shore of a fecund sea . . .’
    Joshua snapped his fingers. ‘Happy Landings. That’s it. You’re from Happy Landings. Both of you, right? You, Mr. Montecute, I recognize your accent – and your name. I may have met your grandmother once.’
    He looked a little