How do geologists make their jobs easier when it comes to dating fossils and rocks?

Answer 1

Well, there are a variety of ways to "date" rocks and fossils. The easiest way is to examine samples above and below the sample in question, and come up with an age relative to those. For example, rock layers a, b, and c are in order with a at the top and c at the bottom. As long as the layers are relatively undisturbed, rock layer c, and therefore the fossils within it, are older than the ones in layer b, which in turn are older than the ones in layer a. This is called the "Principle of Superposition," and it holds true as long as there has been minimal folding, tilting, or faulting of rock layers, which is a form of unconformity. Beyond that, you can use what's called "radiocarbon dating," which utilizes the ratio between isotopes of a certain element within the rock sample which have gradually changed over time. This is a complicated procedure which must be carried out with carefully calibrated and computerized scientific equipment, but the results can be quite accurate relative to the great age of the sample.