Our road cut through all this, following its own dead straight line like a Roman road passing through medieval clutter. But a kilometer or so ahead of us the road came to a dead end. A ridge pushed up out of the plain, terminating the road and blocking our way, stretching to left and right as far as I could see. It glittered and sparkled, as if the land was covered in broken glass.

Rosa was watching my reaction. “Thatis the Reef,” she said. She leaned forward and tapped the pod’s windscreen. “I think this jalopy has some imaging facilities…” A disc of the screen showed us a magnified image of what lay ahead.

I saw that the Reef wasn’t natural at all. It was man-made. It was a heap of automobiles.

Cars upon cars upon cars, piled up, crushed down on each other, glittering with bits of smashed windscreen and gaudy paintwork, the whole thing laced together by a patina of orange rust: there were so many cars they were beyond counting. It was like a vast heaping of dead beetles. And as I learned to work the controls of our pod’s imaging system and turned my gaze, godlike, I saw people crawling, digging, climbing, working at the Reef, everywhere I looked.

The pod rolled to a stop. Its blister popped open, and the Reef rushed in on me. Suddenly the pod was full of a clamor of voices. You could hear individual shouts close by, and beyond that massed voices like the cries of gulls — and then a wider roar, like waves breaking, the sound of a million voices merging into one.

Then there were the smells. It smelled like a road. I smelled tar and asphalt and rubber and carbon monoxide, and a sharper stink that might have been tires burning somewhere. I felt immediately nauseous, but I tried to hide it.

Rosa sniffed up this toxic mix with a look of pleasure. “Ah, bliss. Once the whole world smelled like this, of car. A few hours of it won’t do you any harm.” She was watching me. “I know it’s all somewhat overwhelming.”

I felt uncomfortable to be under the protective wing of a bent old woman close to ninety. I insisted, “I’m fine.”

“Just remember, I have masks.” She clambered out of the car, and I had no choice but to follow.

Away from the smart road surface the ground was just dirt. But it gave slightly as I stepped out onto it, and beetles and spiders and even a few brown-skinned rodents fled from my feet. And the ground was warm, warm beneath my feet. I was standing on the crust of a vast midden, I realized. It was profoundly uncomfortable to walk over that soft, moist, warm surface.

Now we were out of the pod, some of those vendor types crowded closely, yelling, competing for our attention. Most of them bore sticks and skewers with bits of broiled meat. I didn’t like to think about where that meat had come from, but its smell wasn’t as bad as the general old-car stink. I was taller than almost everybody here, even the adults. The people were dressed in rags, but looked healthy enough, well-fed. But the crowding people brought a secondary smell of sweat and body odor that washed over me. I could hear that some of the vendors’ cries were yells of greeting for my aunt. “Mama Rosa!” She replied in a guttural Spanish; I wondered if this place had its own dialect.

And over this swarm of human activity the Reef rose up. We were only in its foothills here, and the constituent cars, crushed, mangled, and stripped, were pressed into the dirt, but its shoulder rose mountainously above us all.

Rosa glanced back at me, grinning, and pushed on into the crowd. There was a danger I would lose her, even in this diminutive mob. I hurried through the sweat and the waving sticks of meat.

We came to a kind of staircase cut, astoundingly, into the heaping of dead cars. Rosa started to climb. I tried to copy Rosa’s brisk strides, but I stepped gingerly on beaten-flat wings and doors and hoods, and crunched over patinas of broken glass.

Above my head I heard a confident cawing. A line of big, black, powerful-looking birds peered down at my slow toil with silent menace.

“Crows,” Rosa said. “They’re a hazard here. They’ll mostly leave an adult alone, but if they see a child they will sometimes try to cut it off. They fly at your head. They herd you.”

“I never heard of crows behaving that way.”

“This is a novel landscape, Michael,” Rosa said. “You adapt or die. Keep an eye on the birds.”

“Oh, I will.”

Maybe a hundred steps above the ground we arrived at a kind of cave, walled by bits of car, cut into the steepening face of the Reef. There were chairs, tables, and a rough-cut doorway leading through to more chambers within.

Rosa entered the cave and, with relief, threw herself down on a chair. I followed suit. My legs were stiff from the climb; I thought Rosa had done remarkably well.

Even the chairs here were old automobile seats, heavily patched with duct tape.

A woman came bustling from the back chambers. She was dressed in an ancient, shapeless smock, and she was healthily fat, though her face was streaked with grime. When she saw Rosa she fussed over her immediately. “Mama Rosa! Mama Rosa!” They exchanged a few words, and then the woman receded to her back room, to come bustling out with a tray of glasses and a bottle.

As she poured, Rosa said to me, “I took the liberty of ordering ahead. The dish of the day, so to speak. The water’s local stuff but don’t worry, it’s clean; engineered bugs see to that.” She held up a glass. “Look, it even sparkles.”

“Rosa, I don’t believe it. Is this is a restaurant?”

“I don’t think I’d give it as grand a description as that. But they serve good food. The best on the Reef!…”

As we waited for the food to arrive, me nervously, Rosa with anticipation, we talked about the Reef, and its strange history.

In the late 2020s, as the Americans had ended their long love affair with the car, the Spaniards had followed suit.

In those pre-Stewardship days Seville had already reached a garbage crisis, and had dumped millions of tons of the stuff in vast overflowing landfills. So for the people of Seville there was only one logical place to get rid of their suddenly useless cars, and that was in the foul-smelling, rat-swarming trash city just over the horizon. The dumping had caught on, and soon cities in the rest of Spain were paying Seville to take on their own refuse, too. “An early example of negotiating for ecological credits,” Rosa said dryly.

Eventually the detritus of the automobile industry of a modern nation had drained here, gathered up by the mechanical muscles of grinders, diggers, and crushers into this great ridge of dead cars. And all the time garbage had continued to pile up around it.

“So the Reef was born. People were already here, picking over the garbage, trying to make a living out of it. But then there was a flood of newcomers. In the 2020s southern Spain was wide open to refugees, especially from Africa. At the Gibraltar Straits you only have to cross a few kilometers of water…”

The final days before the Stewardship had been a time of increasing panic, of a sense of helplessness as problems spiraled out of control. Among the worst was the spread of infectious diseases out of the tropics, like dengue fever, encephalitis, and yellow fever. Uncle George used to say it had been bound to happen. We were tropical animals, he said, who had found a way to live out of the places where we had evolved, all the way to the poles, so it was no surprise that the diseases that had evolved with us should eventually follow. He was right. As the world warmed up and mosquitoes and ticks were able to survive at higher latitudes, the diseases spread out of their traditional ranges, driving human populations before them.

Floods of refugees had broken into Spain and headed for the cities of the south, seeking work, succor, help. “And of course the refugees brought with them the diseases they had been trying to flee,” Rosa said grimly. “The authorities couldn’t keep these plague-ridden undesirables out of the country. But they could keep them out of the towns.”