The main difference between relative dating and radiometric dating is that relative dating is the method of determining the age of rock strata according to their relative depth, while radiometric dating is the method of determining absolute age using decay products of the natural radioactive Isotopes in the material. Furthermore, in an undeformed succession of sedimentary rocks, each layer of rock is older than the overlying one, while electron spin resonance and thermoluminescence are the techniques used in radioactive dating.

In short, relative dating and radiometric dating are two methods of dating fossils . In general, it is important to study fossils to determine what type of organism they represent, how the organism lived, and how it has been preserved on the surface of the earth for the past 4.6 billion years.  

Key areas covered  

1. What is relative dating - definition, dating method, meaning 2. What is radioactive dating - definition, dating method, meaning 3. What are the similarities between relative dating and radioactive dating - overview of the similarities 4. What is difference between relative Dating and Radioactive Dating - Comparison of Key Differences

key terms

Absolute Dating, Fossil Dating, Radioactive Dating, Radioactive Isotopes, Relative Dating, Strata

What is relative dating?  

Relative dating is the method of dating the relative ages of geological events preserved in rock records, depending on the relative ages of the strata. Strata here are the many horizontal layers on the earth's surface.   The study of strata by determining the relative ages of rocks is known as stratigraphy. Relative dating in particular is important for dating sedimentary and volcanic rocks.

Figure 1: The San Rafael swell - sedimentary rock

Principles

In addition, the principle of the original horizontality refers to the horizontal or almost horizontal deposition of the strata. The principle of overlay is also based on the principle of horizontality and states that in an undeformed sequence of sedimentary rocks, each rock layer is older than the one above and younger than the one below. Therefore, in a sequence of rock layers, the oldest are at the bottom and the youngest are at the top.

Figure 2: Layers of a sedimentary rock

In addition, the disturbance of rocks during events such as fault movements is described by the principle of cross-sectional relationships. However, the age of the fossils is important in revealing the relative ages of the rocks preserved in two different areas. Here he of faunal succession principle is useful and it   notes that different fossil species always appear and disappear in the same order and that once a fossil species disappears and cannot reappear in younger rocks.

In addition, index fossils, which occur over a limited time interval, are the fossil types that are important in distinguishing one stratum from another. Significantly, the fossils of pigs or rodents are better suited than guide fossils because they are more common and easier to identify.  

What is radioactive dating?  

Radioactive dating is another method for determining the age of rocks and fossils in particular. It determines the absolute age of geological materials or fossils. In addition, radiometric dating depends on the natural radioactive decay of a particular element, such as carbon or potassium. Radioactive dating techniques also include electron spin resonance and thermoluminescence, which assess the effects of radioactivity   on the accumulation of electrons in traps in the crystal structure of a mineral to determine the age of rocks or fossils.  

Figure 3: Decay of carbon 14

Principles

The atomic nucleus of an element is known to contain protons and neutrons, while the electrons move in orbits around the nucleus. In addition, the number of protons in a given element is constant, but its nucleus can contain a variable number of neutrons that form isotopes of that element with different atomic masses. As an example, the three isotopes of carbon are carbon 12, carbon 13, and carbon 14, with carbon 14 containing an unstable nucleus that breaks down to form its daughter isotope nitrogen 14, which is stable. Here, the time it takes for carbon 14 to split up half of the parent isotope into daughter isotopes is called the half-life   of an isotope.

Typically, minerals in rocks contain these radioactive isotopes and therefore the abundance of parent and daughter isotopes of a radioisotope with a known half-life of a sample can be used to determine the age of that particular rock as a numerical value.  

Similarities Between Relative Dating and Radioactive Dating   

• Relative dating and radioactive dating is to determine two methods in archeology to determine the age of fossils and rocks.  
• The study of fossils is important to determine what kind of organism it represents how the organism lived and how he was received in the last 4.6 billion years ago on Earth's surface.   

Difference Between Relative Dating and Radioactive Dating  

definition  

Relative dating refers to the science of determining the relative order of past events without necessarily determining their absolute age. On the other hand, radioactive dating describes the technique of dating materials such as rocks or carbon, in the course of which traces and radioactive impurities were selectively incorporated during their formation.  

meaning  

Relative dating determines the relative age of rock strata according to their relative depth. Radiometric dating, however, determines the absolute age using decay products of the natural radioactive isotopes.

principle  

In an undeformed sedimentary rock, each lower layer is older than the one above. In comparison, radioactive dating assesses the effects of radioactivity on the accumulation of electrons in traps in the crystal structure.  

techniques  

Also is relatively dating is based on the principle of original horizontality, the principle of superposition, the principle of the cross-section ratios, and t he principle of faunal sequence during the electron spin resonance and thermoluminescence are the techniques used in radioactive dating.  

Type of materials to be dated  

Relative dating is important for dating sedimentary and volcanic rocks, while radioactive dating is important for dating fossils and rocks.  

meaning  

Relative dating determines age relative to the age of the upper and lower classes. While radioactive dating determines the absolute age as a numerical value.  

diploma  

In short, relative dating is the method of determining the relative age of a fossil. In general, it depends on the age of the upper and lower layers of an undeformed succession of sedimentary rocks. In contrast, radioactive dating is the method of determining the absolute age of a fossil. However, it uses the remains of radioactive traces. The techniques involved in the process are also electron spin resonance or thermoluminescence . Hence, the main difference between relative dating and radioactive dating is in principle and manner of dating.  

References:

1. Peppe, DJ & Deino, AL (2013) Dating rocks and fossils using geological methods. Nature education knowledge 4 ( 10 ) : 1. Available here .

Image courtesy:

1. "Interesting dirt paint near Emery, Utah" by Ken Lund ( CC BY-SA 2.0 ) via Flicker 2. " Fossils " by Kurt Rosenkrantz ( CC BY-SA 3.0 ) via Commons Wikimedia 3. "Carbon Dating- Flashcards "From Zappys Technology Solutions ( CC BY 2.0 ) via Ficker