Carbon dating is actually only effective up to about 50,000 years, so its really only ideal for tracking human history after we started migrating out of Africa. This is because the unstable carbon-14 isotope only has a half-life of about 5700 years.
There are many other forms of radiometric dating, though. Uranium-lead dating has proven relatively accurate for periods of time between 1 million to 4.5 billion years ago.
Note: I'm not a geologist. I remembered that carbon was only effective for a few thousand years from a geology course I had in college, but all of this information is actually taken from articles on wikipedia: http://en.wikipedia.org/wiki/Radiometric_dating