Professor Okafor excavated the Roman mosaic one row at a time, starting from the access trench at the top of the grid and working down. By the third season the entire floor was exposed — every tessera gleaming in the sun for the first time in two thousand years. Then the tremor hit. A section of the trench wall collapsed inward, burying the topmost row of tiles under a metre of earth while the deeper rows, set into bedrock, stayed clear. She spent the next season re-excavating what the earth had reclaimed.