Superposition is a relative dating method that looks at the layers of soil beneath the Earth’s surface. Layers of soil that are younger are found on top of layers of soil that are older. The Law of Superposition isn’t only used by archaeologists, though – it is also very important to other scientists like paleontologists and geologists.
At first superposition might seem pretty simple: older things on the bottom, newer things on the top. But what happens if something moves the soil around, like a farmer’s plow or an animal burrowing into the earth? That is when things can get a little tricky.
A good way to think about superposition is to imagine a messy desk, full of four weeks of mail! Say one day you need to find a letter from three weeks ago in those layers of envelopes, how will you know where to look in the pile when there are two weeks’ worth of newer mail on top? To get to the letter from three weeks ago, you will have to dig and sift through the other weeks before you can find the one you are looking for. When you’ve found it, there will still be about a week of even older mail left in the desk. Read more