LXX Gen 8:5

τὸ δὲ ὕδωρ πορευόμενον ἠλαττονοῦτο ἕως τοῦ δεκάτου μηνός· ἐν δὲ τῷ ἑνδεκάτῳ μηνί, τῇ πρώτῃ τοῦ μηνός, ὤφθησαν αἱ κεφαλαὶ τῶν ὀρέων.

And the waters continued to recede until the tenth month, and on the first day of the tenth month the tops of the mountains became visible.