In both, the flood is FORESEEN and the total record is deliberately buried in advance of it — a planned deposit with planned retrieval, not accidental survival. Same three-beat structure: warning, interment underground, post-diluvian recovery for mankind. Raw material for the Custodian doctrine: someone was told, and someone prepared.
Kronos gives advance notice of the flood 'in a vision' and commands Xisuthrus to write 'a history of the beginning, progress, and final conclusion of all things' and 'bury these accounts securely in the city of the Sun at Sippara'; after the flood a voice orders survivors to dig the writings up and make them 'known to all mankind.'
The Theban syringes were built by 'men skilful in the ancient mysteries, by means of which they divined the coming of a flood,' who carved their sacred rites in underground galleries 'lest the memory of all their sacred ceremonies should be lost.'
Berossus quotes verified at Wikisource (SBELE vol. 1, Fragments of Berosus, tr. from Cory); Ammianus 22.15.30 verified in Yonge's 1862 translation at tertullian.org.
Our fact-checkers corrected the first draft:
The same three-stage avian reconnaissance protocol from a grounded vessel, with overlapping species (dove, raven) and the identical inferential logic: the bird that does not come back is the good news.
An identical four-beat sequence: landing → burnt offering → the deity smells the smoke and is moved → vow of never-again sealed by a physical token of remembrance (a string of sky-blue lapis at the goddess's throat; a bow of color in the cloud).
In both, heaven never announces the flood openly.
Same skeleton with no shared geography: humanity's crime is an affront to the senior god's comfort or dignity, a council formalizes extermination, the killing is halted mid-course by subversion within the pantheon itself, a remnant survives, and the wearied god afterward binds or removes himself.