Evidence for an Old Earth

Read The Age of the Earth by G Brent Dalrymple for a load of such. Here's just one bit:
A variety of radioactive isotopes are found in rocks on Earth. Some, like potassium 40, rubidium 87, and uranium 235 and 238, have half-lives of hundreds of millions of years or more, and are used for radiometric dating. A wide variety of these are found in various rocks, though only a few are useful for dating due to rarity or technical reasons. Some, like radium or polonium, have much shorter half lives but are continuously formed by decay of uranium or thorium.
But a variety of other isotopes - aluminum 26, technetium 99, promethium, manganese 53, and others - have half lives of between several thousand and about 80 million years. NONE of this last class are found on earth, with a few interesting exceptions. ALL of the isotopes with half-lives in this range have decayed to other elements since the Earth was formed. Enough half-lives have elapsed for these "short-lived" isotopes, present in the nebula that condensed to make the Solar System and us, to be below detectable limits. But the longer-lived ones - those over a hundred million years or so half-life - are still around, and they were formed in the same stellar furnaces as the short-lived ones.
There's one plausible explanation for this, and it's a 4.5 billion year old Earth.

By measuring the number of decays per minute in a known amount of material and dividing the rate constant you get into the natural logarithm of 2. They've been doing it since Marie Curie.

This is like asking a machinist why he needs a micrometer when he already has a yardstick - it's more accurate!!!
PE, please read the link Rrhain gave in post #8 above - it handles the objections in your source very well. If there are still points you want to discuss, bring them back here, but read the article first.

Would you provide documentation of this happening, please?

Say either of those in this part of Texas and you'll probably end up beat to a pulp in a bar ditch.

And the cypress trees, having knees, also had feet and ran to higher ground, while the poor footless seed ferns in the same swamp drowned and went extinct.
I don't think so.
The fossil record can't be massaged enough to look like that's what happened, and geologists had already figured that out by 1830. Try a newer argument - this one won't swim.

Why, then, is pollen from grasses found only in Cenozoic sediments - nearly everywhere you look in Cenozoic sediments - and never, ever, not once in Jurassic or Devonian ones? Why does coal from the Pennsylvanian, though made up almost entirely of plant matter, have not even a trace of a fossil of grass or of any other angiosperm ("flowering plant")? Was there some force that kept grass pollen suspended in the atmosphere until all the trilobites and dinosaurs and ammonites had been buried?
Believe what you like, but at least look at what you're arguing against.
And learn to use the "quote" function: {qs}what you are quoting{/qs}, only with square brackets instead of curly ones. It makes reading posts a lot easier.