Genesis says He created the universe, the earth, and all life on it in six days. That is laughable on its face.
Even twisting the literal meaning of six days to be some other length of time means that you've abandoned the truth of Genesis. Once you do that, you may as well accept the rest of science, including evolution.
Saying that Genesis can't be accepted on the time required to create the universe and all life, but can be trusted on its description the creation of man is contradictory.
Where does it say he created the universe in six days?
Actually, that would be presuming that Gen 1:1 is included in the first day. A friend, who knows Hebrew, told me many years ago, that there is a change in tense and meaning of the words used for create and make between verse one and two. It indicates that verse one is a creation of something new, never before created; where verse two is a word that indicates remaking, or fixing up. That is not too much of a stretch in the interpretation of the Bible and considering how Ussher arrived at his chronology, I see nothing inconsistent with it. Usshers Chronology is weak at best, IMO, as he presumed a direct father to son descent. The time period between The creation account and the Flood is very specific but beyond that, there is room for error. Since the BIBLE doesn't state when the Earth was created I don't see and problem with accepting an old Earth.