For example, carbon dating is used to determine the age of organic materials.Once something dies, it ceases taking in new carbon-14, and the existing carbon-14 within the organism decays into nitrogen at a fixed rate.

Relative dating and radiometric dating are used to determine age of fossils and geologic features, but with different methods.

Relative dating uses observation of location within rock layers, while radiometric dating uses data from the decay of radioactive substances within an object.

Relative dating helps determine what came first and what followed, but doesn't help determine actual age.

Radiometric dating, or numeric dating, determines an actual or approximate age of an object by studying the rate of decay of radioactive isotopes, such as uranium, potassium, rubidium and carbon-14 within that object. This rate provides scientists with an accurate measurement system to determine age.

Today there are two common practices for dating rocks and strata. Geologists use what they see and some simple strategies to relative date the rock layers found in the Grand Canyon.

The first is called absolute dating, where geologists use radioactive decay to determine the actual age of a rock. Let's say you are a geologist who is tasked with dating the rocks found in the Grand Canyon, and you must do so in the canyon without the aid of any laboratory equipment. Relative dating doesn't really give us an actual 'age,' but it does put things in sequential order.

Principle of fossil succession: This principle is very similar to that of superposition.

The only exception is instead of rock layers we're focusing on fossils.

You can't start with the top layer and add the ones under it since there would be nothing to build on.