The first change came in the color of the morning haze.
On day1673, Garn’s upper lookout sent a strip of gray cloth down the warning line. The lower air had stopped lifting cleanly out of the wash. A warm layer lay over cooler ground, holding mineral breath beneath it. The dangerous convergence was still ahead, but the ordinary morning work allowance had shortened.
Nall closed the lowest inspection passage.
The local receiving bank continued under its own extraction fan.
For half an hour, that was enough.
Then the fan’s inlet reading changed.
It still moved air. The motor had not failed. The intake had begun drawing from the warm trapped layer instead of the clearer current above it. A machine could work perfectly and bring the wrong thing where people stood.
Nall reduced the bay’s turn and sent the workers to the upper room.
