Genesis 7:6

7:6 Noah ¹  was 600 years old when the floodwaters engulfed ²  the earth.

Genesis 7:10

7:10 And after seven days the floodwaters engulfed the earth. ³ 

[7:6]  ¹ tn Heb “Now Noah was.” The disjunctive clause (conjunction + subject + predicate nominative after implied “to be” verb) provides background information. The age of Noah receives prominence.

[7:6]  ² tn Heb “and the flood was water upon.” The disjunctive clause (conjunction + subject + verb) is circumstantial/temporal in relation to the preceding clause. The verb הָיָה (hayah) here carries the nuance “to come” (BDB 225 s.v. הָיָה). In this context the phrase “come upon” means “to engulf.”

[7:10]  ³ tn Heb “came upon.”