Q: The blue channel has become the center of the flood-map debate. What do we know about it?
Ava Korr: We know it is present on the surviving sheet and absent from the map copy made for the public catalogue. We do not yet know which hand added it.
Q: The note beside it is sometimes described as a surveyor’s mark.
Korr: That is an attribution, not a fact. The paper shows a later ink and a different hand. The loose notes in the same folder do not identify the writer.
Q: Could the line show a real spill channel?
Korr: It could. The mapmaker’s original work places a sealed door nearby. But the modern survey has not found a matching channel, and the map’s scale is not precise enough to settle that alone.
Q: Why publish the uncertainty instead of waiting for an answer?
Korr: Because people are already using the line to make claims about the old flood route. The catalogue should say what is observed and keep the interpretation open.
Korr says the archive will release a high-resolution copy with the later marks dated separately. That will not prove who added the line; it will let readers examine the evidence on which the claim rests.
