Jason Fox asked me this question:
"Ian, are you a Theistic Evolutionist? If so, what do you base the age of the earth on? If not, how old do you say the age of the earth is?
"The reason I ask is you make references to an old earth."
To which I said:
No...not a theistic evolutionist...and I hold the Bible to be literally true in all that it teaches, affirms and records.
However..I'm not convinced that the Young Earth interpretation of the Hebrew in Genesis is the only way those passages can be read, and so I throw the whole question into the "Ultimately, we don't know" category.
There are gaps in the genealogies recorded in the Bible, and no knowing for certain how much time intervened.
The Earth could be around 10,000 years old if, in fact, God had to set the universe up with 13 billion years "on the clock" so to speak, so that the ideal conditions for life existed immediately upon creation.
But equally, if yom indeed can refer to an indefinite period of time, as it does in some passages, then a day to God may be 800 million years to us..
Gleason Archer and Norman Geisler have both authored some important essays on this question in order to reconcile it to Biblical inerrancy.