"I can't imagine that a scientist would just assume that 2 fossils found at similar depths on opposite sides of the world are the same age."
lol. Oh man. I'm so sorry. Ok, two things. First of all, it is very unlikely that you will be able to independantly test both fossils AND get the same age. Its been awhile since I've acquainted myself with these types of minute details, but I think such instances are very rare, if even non-existant altogether. Sorry, guy. They would just make that assumption.
Second of all, this practice is already well known and documented. They have what they call 'index fossils.' See this:
http://pubs.usgs.gov/gip/geotime/fossils.htmlAs you can see, that is the US Geological Survey, and not any creationist or even explicitly evolutionist organization. You should ask yourself- which came first, evolutionary theory which told them which animals came first, or absolute dating of the animals. My favorite line came from the page linked off of that page (
http://pubs.usgs.gov/gip/geotime/relative.html) : "Today, such a proposal appears to be quite elementary but, nearly 200 years ago, it amounted to a major breakthrough in scientific reasoning by establishing a rational basis for relative time measurements"
A major breakthrough in SCIENTIFIC REASONING. a RATIONAL BASIS. lol, so... in otherwords, it was merely a new way of looking at the data, and not any real set of empirical experiments. It was a new interpretation, and I would suggest specifically antagonistic to any notion that Genesis might be true. The site gives us evidence of that bias on its own: "At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away."
If you thought there was a wide body of actual unbiased, direct experimentation supporting the modern notions of the geologic column, I'm afraid you are mistaken.
Here is a link to the google search of
'absolute dating of index fossils'Good luck finding any evidence that fossils themselves are very often dated using absolute dating methods.
Sorry.