I'll be posting lines of evidence against a young earth. The first I don't think anyone has noticed before, the long lived Greenland Shark. It reaches maturity at a staggering 150 years of age and has a gestation period of at least 8 years. If more than 38 generations existed, the Earth could not be 6,000 years old. Based on the population, more than 38 generations is all but guaranteed.
I think a lot of folks forget the bible is not a science book. It did not impart 24th century knowledge on ancient people. It's not about that. I like to ask YEC's how much time passed between the beginning of the first day, Genesis 1:3, and what comes before it.
I kinda see it this way: When the bible speaks of the heavens and the earth, It is generally talking about the sky and the SURFACE of the earth. So bear with me on this:
It can be a practice in art where someone creates a painting on canvas and then whitewashes it and creates another painting on it. This can happen several times. If you then carefully peel back the paint, you can see the painting below the exposed one. You can then continue to see earlier and earlier paintings.
So, the canvas is the surface of the earth, and the current painting we see is "6,000" years old, but if you peel it back, you see the previous paintings. You see fossils from previous paintings, the Cambrian explosion, mass extinctions, etc. And each of these paintings is called an "age".
So, the earth is VERY old and a LOT of time passed between Genesis 1:2 and 1:3. There were previous ages. But the current age is roughly 6,000 years old. I've not yet found a bible verse to contradict this, and scientific discovery supports it.
BTW, the next "whitewashing" comes by fire, according to The Revelation of Jesus, and even the sea is burned up, and then the New Jerusalem comes down and Jesus reigns. Solar flare, perhaps?