Every commit has both an author/author-date and a committer/committer-date. The former are retained during a rebase, the latter are reset. However, you can use --ignore-date to reset the author-date, or --committer-date-is-author-date to retain the original committer-date.

In any case, when using git log, you can override its default of listing commits in reverse chronological order with --topo-order or --date-order.

There are actually two dates associated with each commit. I cat recall the names for them off he top of my head but they're basically created_at and modified_at, and the modified_at ones will be chronological after a rebase.