Another key issue, demanding a young Earth, is this foundational teaching in Romans 5:12: “Therefore, just as sin entered the world through one man, and death through sin...”
If Adam’s choice first brought sin and the resulting death into the world—even the animal world (the WHOLE world), than vast ages of evolution before (which is after all, in the “survival of the fittest” a death-driven scheme of development) are not possible.
The fact that we have the little phrase “according to their kinds” repeated after each creation in the creation account too—refutes the evolutionary key of all creatures coming from one “kind,” (the evolutionary tree) which clearly teaches humans are nothing but animals.
The most important thing we need to believe as Christians is the first verse of Genesis, and that's the whole enchilada. That's the fundamental principle in all of this. It's a solid truth, and someday we'll likely know the whole truth about all of this.
I'm not a Darwinist at all, but forcing people to believe in a young earth is not only not necessary, it's flat out wrong.
The "age of rocks" discussion is really a red herring because the issue is not the age of the earth but the origin of living things.
However, for the subject of the age of the earth, check out "The Gap Theory" if you haven't already. I believe it to be the best biblical explanation for the earth being as old as science discovers. All true science can do is uncover what's been in the Bible all along.
Seriously? You're not even going to finish the verse you're quoting for a proof-text? ". . . and so death passed upon all men, for that all have sinned."
There's nothing in Romans 5 to indicate that sin brought about animal death, only human death due to being separated from God by sin and from the Tree of Life by God.
The more I've learned to read the original Hebrew of Genesis, the more comfortable I am that the six days of creation can just as easily be six ages or epochs of creation without requiring doing violence to or allegorizing the text.
Shalom