After the last siren

This original descriptive passage presents an invented quarry at the end of a working day.

From the viewing platform, the quarry appeared to have been planned with a ruler. Roads descended in sharp turns from one level to the next. The exposed rock had been cut into broad steps, each one edged by a straight yellow safety line. Even the shadows seemed organised, lying in rectangular blocks beneath the parked machines.

The final siren sounded. A small group of workers crossed the quarry floor and passed through the gate without speaking. Their orange jackets moved together until the bend in the road removed them from sight. Engines stopped one by one. An excavator remained beside the lowest wall with its bucket raised, as if a command had reached it halfway through an action.

Without the engines, quieter movements became noticeable. Water slipped from a crack and travelled across the lowest road, ignoring the painted arrows. Pebbles released from the upper face clicked down the terraces and scattered over the yellow line. Near the gate, rain had softened a white number until it resembled a question rather than an instruction.

The shower strengthened. Channels intended to carry water away filled with dark grit, while a pool widened around the tyres of a silent truck. Reflections of cut ledges wavered on its surface, breaking the quarry's neat steps into crooked fragments. A tuft of grass, growing from a shelf too narrow for a boot, bent flat beneath the rain and rose again when the drops weakened.

Across the quarry, someone had marked tomorrow's work on the rock with a row of red crosses. In the wet, each cross developed a thin downward stroke. The lowest one disappeared completely behind the spreading pool. From the platform, the remaining marks looked less like decisions than brief suggestions made against the cliff.

A loose stone fell somewhere out of sight. Its first knock was followed by smaller knocks that passed around the empty space. For several seconds, the sound seemed to come from every level at once. Then the quarry was quiet enough for the rain to be heard striking the metal roof of the shelter.

Floodlights came on beside the gate, restoring the roads and machines to view. Their beams were bright but shallow: beyond them, the upper rock had already become a single dark wall. The quarry still carried its lines, numbers and carefully measured levels, but the rain continued to move across them, altering each boundary it reached.

How does the writer make the quarry seem both shaped by the workers and resistant to their control? Support your answer with references to the passage.