Differing definitions is a possibility. I understand you to be satisfied with the numbers geologists propose. That's fine. There is much about their work I appreciate, but I feel in no way obligated to accept whatever they propose. That would be arbitrary, too. Quantum mechanics is creeping up on a reality that makes a billion year proposition as relevant as a nanosecond proposition, all of which is very much in accord with what the biblical text teach regarding the Creator.
The Bible talks about a “firmament” 15 times. When the old testament was written all educated people believed there was a literal invisible dome above the earth that separated the heavenly ocean from the earth. Stars were embedded into it and the sun and moon moved across it.
Did the Bible lie about this model? Or do you believe that you must believe in the firmament because it’s described in the Bible?