Unfortunately, as old as Richard is, I don't think he was present when the earth was created. So he can't definitively say without any room for doubt that the earth was created more than 6000 years ago. Personally, I think millions or billions of years could have passed between Gen 1:1 and Gen 1:2. Personally, I've read the part in the Bible that says that a day with God is as 1000 years, and 1000 years with God is as a day. I've interpreted that to mean that with God, the timeline is irrelevant.
Responding to fpsqt (whose post was two weeks earlier than this one), I see Mr. Dawkins mentally stretching as well, and his logic also is flawed. One cannot prove a negative, yet he persists in attempting to do just that. The entire universe has not been and cannot be explored in our lifetime, so for him to say without equivocation that God does not exist is astonishingly arrogant.
His decision to believe such things is for him alone, not for anyone else. The readers of this post may disagree with me; your belief likewise is for your and for no one else. My belief is for me and no one else. In line with his own statement, Mr. Dawkins may and should present his views as options for his listeners and readers to pick what they wish to believe. For him to adamantly insist that I accept his theory as undisputed fact flies in the very face of his chosen style of research ("look at the options and select those you like").