The Silt Basin

The rain stopped at a line he could not see.

Halloran walked out of it and the mud went from soft to fired clay in one step, cracked into plates the size of doors, and the air stopped smelling of anything. He put his tongue against the back of his teeth. Rain. Then salt. He had learned to taste the seams before the instruments found them, which was not a skill anyone at Apex had thought to write down.

The basin had been a sea until eleven thousand years ago and a survey grid until Tuesday. Finch had removed one post at a time. The crossing markers stood at their old spacing for two miles and then stopped. Beyond them Halloran had to test each square. Rain in one. The same storm in the next, dried to a white crust with the drop marks still in it. A third square had never had the storm at all and held a pickup truck with 1979 plates and no rust.

He stopped at the edge of the square and took the survey chain from his belt. Six links, a lead weight, a handle long enough to keep his fingers on his side. He swung the weight into the square. It fell toward the truck, missing vertical by eight degrees.

The map in his notebook gave three degrees. The entry was eleven days old.

He put one boot across, kept his weight behind it, and watched the chain. The direction held. He brought the other foot over and let his right shoulder take the change. The weight of the notebook against his chest shifted toward the truck.

The truck weighed less than it should. He could tell from twenty feet, from how the springs sat. Its front wheels were turned hard toward a road that ended at the square's northern edge. A woman's straw hat lay on the passenger seat. The crown had been pushed in by a heavier object, now absent. He checked the cab and the bed. No one.

The next marker should have been visible through the windshield. Finch had left its socket in the ground and laid the post beside it, parallel to the seam. Halloran could have reset it in less than a minute. He looked toward the tower, entered the missing marker in his book, and went on.

His right knee required a brace. The gravity changed at the seams by a few percent; nine hundred such changes a day for thirty-two years had damaged the knee and the disc above it. He compensated by carrying his right shoulder low. Younger Apex people called it the Zone lean. He had stopped correcting them.

The tower was a mile off. Apex survey, class two, forty meters of lattice steel with a mast, planted in 2003 on a square that had held still long enough to pour a footing. Finch was at the base of it. Halloran could see the coat. Finch always wore the coat, and he wore the mask, and he did not hurry, which was the thing Halloran found hardest to forgive. A man who was not hurrying had time.

He raised the glasses. Finch knelt at the footing with both hands inside the service box. The right hand thinned until Halloran could see a bolt through it. The cuff remained opaque.

The tower's return lamp lit. The hand filled out again.

No marked boundary crossed the footing. Halloran watched through a second interval, keeping the hand and the lamp in the same field of the glasses; the light returned with the hand, though at this distance he could not establish which came first.

Halloran lowered the glasses. There were two ways to the tower. The survey route passed around the south side of a drainage cut and crossed nine tested squares. The direct route crossed four. Finch had used the direct route; his footprints were visible in the salt until the second seam.

Halloran took it.

At the first crossing he could no longer hear his boot soles. He tapped the handle of the chain against a remaining post. Nothing. In the next square the tapping caught him from behind, followed by three of his own steps. He marked the delayed square with two strokes on the map. Sound had been reliable there last week.

The distance closed more slowly than the ground under his feet allowed. He checked the tower's apparent height against the graticule in the glasses. One thousand and forty meters. He walked fifty paces and checked again. One thousand and twelve. The maps of this basin were compiled from measurements made within each square. Across several squares they no longer added.

He shouted Finch's name. He gave it twenty seconds to arrive and lifted the glasses again.

Finch closed the service box. He looked toward Halloran without raising a hand.

Halloran started walking faster and the knee said no and he kept walking.

At eight hundred meters the tower leaned.

That was all. The mast tipped four degrees off true and stayed there, and the lattice below it stayed straight, and nothing else happened. No sound. Finch stood up and stepped back. Halloran stopped, because he had seen this before, twice, and both times he had been the one standing too close.

At six hundred meters the sound arrived. It came across the squares in pieces, a flat clap that had been through several years on its way, and under it the ring of steel already falling.

At four hundred meters the tower caught fire. It was still standing. The mast was still four degrees off. Flame ran up the north face of the lattice in a sheet, blue at the bottom: thermite. The heat reached him through a square where the air was dry and stopped at the next seam.

Then the detonation, which was the first thing that had actually happened.

He saw the footing go. He saw the whole forty meters of it lift and open at the base and come down across three squares at once, and in one of the squares it was already rusted, and in one it was still bright, and in the middle one, the one Finch had been kneeling in, it was gone, because that square had moved on to a Tuesday when the tower had never been built.