The dike they were building around Burroughs was two hundred meters high and three hundred meters wide. Maya found the concept of a dike to protect the city disturbing, though it was clear from the aerial shots taken of it that it was another pharaonic monument, tall and massive. It ran in a horseshoe shape, with both its ends up on the slope of the Great Escarpment, and it was so big that there were plans to build on it, to make it into a fashionable Lido district, containing small boat harbors on its water side. But Maya remembered once standing on a dike in Holland, with the land on one side of her lower than the North Sea on the other side of her; it had been a very disorienting sensation, more unbalancing than weightlessness. And, on a more rational level, as news programs from Earth now showed, all dikes there were currently, stressed by a very slight rise in sea level, caused by global warming initiated two centuries before. As little as a meter’s rise endangered many of the low-lying areas of Earth, and Mars’s northern ocean was supposed to rise in the coming decade by a full kilometer. Who could say whether they would be able to fine-tune its ultimate level so accurately as to make a dike sufficient? Maya’s work in Odessa made her worry about such control, though of course they were trying for it themselves in Hellas, and thought that they probably had it. They had better, as Odessa’s location gave them little margin for error. But the hydrologists also talked about using the “canal” that had been burned by the aerial lens before its destruction, as a runoff into the northern ocean, if such a runoff became necessary. Fine for them, but the northern ocean would have no such recourse.

“Oh,” Diana said, “they could always pump any excess up into Argyre Basin.”

• • •

On Earth, riots, arson, and sabotage were becoming daily weapons of the people who had not gotten the treatment— the mortals, as they were called. Springing up around all the great cities were walled towns, fortress suburbs where those who had gotten the treatment could live their entire lives inside, using telelinks, teleoperation, portable generators, even greenhouse food, even air filtration systems: like tent towns on Mars, in fact.