The Difference Between Relative Dating & Dating

Relative Dating

• Simply put, relative dating is the process of dating a rock or fossil based on where it is buried. It is not so much about measuring years as it is about putting together a timeline. The rocks of the earth can be found in layers called strata. As layers of sediment settle over time, new layers settle above them. So as you go down you find older strata, and a fossil found in the lower strata of the Earth is older than one found several strata up. This is known as the Principle of Superposition.

Method

• While relative dating may seem simple enough to do in a single area, the real challenge is applying it all over the world. This is where the Principle of Lateral Continuity comes in. Using this principle, geologists can link layers to each other if they are separated by distance. Relative dating also relies on the Principle of Faunal Succession. In short, this principle states that fossils found in a particular order in one area will predictably remain in that order somewhere else. This has exposed the way in which fossils become more complex as they climb up the strata, creating a timeline for evolution.

Absolute Dating

• While relative dating is used to establish an order of events, absolute dating deals entirely with specific age. The age of a rock or fossil is established by measuring the amount of radioactivity in it. This is also known as radiometric dating. British physicist, Lord Rutherford, proposed the idea in 1905. By the 1950s, radiometric dating was considered accurate and reliable.

Method

• Absolute dating is founded on the concept of radioactive decay. The principle behind this decay is that atoms of radioactive materials are unstable. As a result the atoms are gradually emitted and transformed into more stable elements. The rate of decay varies from one element to another, but all elements decay at their own constant pace. The speed of decay is known as the half-life, which is the amount of time it takes for the material to emit half of its radioactivity into other elements. The radioactive material is called the parent, while the stable material it converts to is called the daughter element. For example, potassium decays into argon. Potassium is the parent while argon is the daughter element. The half-life of the material is taken into consideration. Then the amount of the parent element is compared with that of the daughter element.