How to show posts by publication date (not by updated date)

We are using your Posts block for our blog roll on our homepage. Currently, if we update a post with new content and republish it, then it brings it back to the top of the blogroll so it will reappear on the homepage. This is not what we want, we want the posts that appear on the blogroll to be ordered ‘newest to oldest’ in terms of publication date, not the date it was updated on.
Is there some way to accomplish this?