Obviously older than the 6000 years which Bishop Usher deduced from the old testament but, in all likelihood, nowhere remotely close to the 4 billion year figure which atheist scientists put out.
The various systems of dating geological forms appear to be based on nothing much more than belief systems and circular reasoning and it is now known that the Mount St. Helens volcano has produced varves and other "geological evidence" which according to theory should have taken many thousands of years to produce.
One interesting comment which I've seen on an FR posting and saved, apparently from a good mathematician, is the following:
Lord Kelvin stopped Darwinism dead in its tracks when he made an irrefutable thermodynamic calculation that at the rate which the Earth is cooling off (and heat is being conducted from the interior to the surface and then radiated into space) the Earth could not possibly be more than 2 to 20 million years old. This really put "the fear of God" into the staunchest Darwinists for a while.But when radioactivity was discovered, the uniformitarians rejoiced because they had found a "new" source of heat to prolong the Earth's life-span. But they _failed_ to repeat Kelvin's calculation, because the results would have been too embarrassing. I once found in a geology text-book an account of Kelvin's calculation, which (using Fourier transform solution) I modernized by incuding on the right-hand side of the equation as a "source" of energy inside the Earth the _maximal_ modern estimates of abundance of radioactive materials inside the Earth (which I got from publications by famed Princeton physicist Dicke). Part of the reason that I was fired from BYU is that I circulated a copy of my paper showing that with inclusion of the heat sources which Lord Kelvin had not known about, the _MAXIMAL_ age of the Earth gets revised upwards from his 20 Million years to only about 200 Million years (a far cry from the billions proclaimed by uniformitarian geologists who are about to experience a sudden fall when my friends start to market cheap Radio-Shack type gadgets by means of which high-school labs & home workshop hobbyists can cause Uranium and Thorium to do in 20 minutes what the Establishment claims would take "45 billion years"!).
It sounds kind of like you can't even talk about this kind of stuff in American Academia yet. If that's the case, then Ohio and other states are not only going in the right direction, but in a NECESSARY direction. It sounds like the evolutionists have pretty much stifled debate and discussion in academia.
You can find something, a web page or a crackpot book, to back up any goofy thing you might care to advance in an argument. Most people would, before biting, ask how much good scholarship they are throwing away versus how sound is the evidence for the "revolutionary" concept, etc. But some only ask "How sexy is that revolutionary version to me?"
The age of the earth and solar system are not in major doubt. Several lines of evidence converge. Anyone peddling anything else needs to deal with why that is so.
Lord Kelvin (William Thomson) was in his prime during the reign of Queen Victoria. It is a classic creationist tactic to find something in print -- no matter how old -- to "disprove" evolution, regardless of how much progress science has made since the work they are quoting. Here's a site that gives the age of the earth, as the information was gradually developed historically. Lord Kelvin's work is mentioned, as one step along the way to our present understanding. Alas for the reputation of the source of your information, Kelvin's estimate is obsolete (but it must have been a show-stopper during the McKinley administration): The Age of the Earth.