How is absolute dating different from relative dating
Imagine someone telling you a story where all the important events happened in the wrong order. It might be confusing, or even make no sense at all.
Being able to tell how old things are and put them in the right order is one of the most important skills archaeologists have. We call this skill dating because it is how we organize our discoveries in time, like dates on a calendar. Archaeologists use two kinds of dating methods: relative dating and absolute dating.
In relative datingwe determine which things are older or younger based on their relationships. For example, we know from geology that soil layers near the surface of the ground are usually younger than those deeper down.
This relationship helps archaeologists know that objects we find deep in the ground are older than things we find closer to the surface. But how old is old?
What is the difference between absolute and relative dating methods
To find the specific age of an object, archaeologists use absolute dating. Absolute dating methods measure the physical properties of an object itself and use these measurements to calculate its age.
One of the most useful absolute dating methods for archaeologists is called radiocarbon dating. It works by measuring carbon isotopeswhich are versions of the element carbon. All isotopes of carbon have 6 protons but different s of neutrons. One of the carbon isotopes that occurs in nature is radioactive; it has 8 neutrons and is called carbon All plants and animals take in radioactive and non-radioactive carbon when they eat and breathe.
When they die, the carbon in their wood and bone starts its radioactive decay process.
This means the amount of carbon goes down over time in a predictable way. However, the amount of stable non-radioactive carbon remains the same. In radiocarbon dating, the amounts of stable carbon and carbon in a piece of bone or wood are counted.
The ratio of stable carbon to carbon is then used to calculate the date when the radioactive decay process started; in other words, the time when the plant or animal died.
How is radiometric dating of fossils different from relative dating
This means that by using radiocarbon dating, we can tell when someone in the past hunted an animal or cut down a tree at an archaeological site. Since they are made of wood, we were able to use radiocarbon dating to learn how old they are. Radiocarbon dating of the hull found that it is between and years old. Another canoe, 24 feet in length was discovered in Lake Waccamaw. The radiocarbon date for this canoe tells us it is between and years old.
Relative vs absolute age dating
The oldest canoe ever found in North Carolina is a canoe from Lake Phelps; radiocarbon dating of this canoe indicated it is about 4, years old! So very tiny things like carbon isotopes can be used to answer really big questions!
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