Question

How can we determine the age of fossils?

Answer 1

To date fossils, scientists utilize relative dating to sequence events and absolute dating, like carbon-14 dating, to establish approximate ages in years. Carbon-14 is effective for dating remains up to 50,000 years old, while other isotopes are used for older fossils.

Step-by-step explanation:

To determine the age of fossils, scientists use two main methods: relative dating and absolute dating. Relative dating involves sequencing fossils and rock layers to create a chronological order without determining the specific age in years. Absolute dating, on the other hand, provides an approximate age in years for the fossil. This is frequently accomplished using radiometric techniques such as carbon-14 dating.

Carbon-14 (C-14) dating is the most well-known method for determining the absolute age of once-living materials. The premise is simple: living organisms absorb Carbon-14 from the environment, and this isotope decays at a known rate, with a half-life of 5,730 years. By measuring the amount of C-14 that remains in a fossil, scientists can estimate how long ago the organism died, up to approximately 50,000 years ago. For older fossils, other isotopes with longer half-lives, such as potassium-40, may be utilized instead.

Answer 2

In order to estimate the age of fossils, two methods must be used: relative dating and objective dating.

As a rule, fossils themselves cannot be directly dated because most of them have little or no organic material left, and carbon-14 dating is only useful up to approximately 35000–50000 years in age. Those that are more ancient than that must be dated using the rock strata in which they were discovered.

For the most part, scientists have been studying rock strata for at than 300 years, and they have been able to determine with great precision the sequence in which the rock layers were formed. Rocks are classified into eras, with the oldest being the oldest and the youngest being the youngest:

PreCambrian, Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Paleogene, and Neogene are the geologic periods represented by the following names: PreCambrian, Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, and Neogene. Unless there has been an obvious disturbance, rocks are always found in this sequence all across the planet, regardless of where they are found. A fossil discovered within a particular rock layer can then be assigned to one of these age ranges, allowing scientists to locate the fossil within the appropriate age bracket.

There is only one flaw in this approach: knowing one layer is older than the next does not provide us with an objective date for the rock layer in question. Because of everything we've learned so far, we can only conclude that a cretaceous fossil is younger than a Jurassic one.

Radiometric dating is the method that scientists use to establish an objective date. Sedimentary rock, which contains the vast majority of fossils, cannot be directly dated, whereas igneous rock, on the other hand, can be. By analyzing the quantity of radioactive decay in specific elements since the igneous rock crystallized, it is possible to determine the age of the rock to a pretty exact level of accuracy. 2.4 million-year-old igneous layer found on top of sedimentary rock indicates that the sedimentary rock was laid down before the 2.4 million-year-old volcanic layer appeared. You can identify that the sediment was set down between 3.2 and 2.4 million years ago by the presence of a second igneous layer below it that has a 3.2 million-year age. A fossil found inside that stratum must be older than 2.4 million years and younger than 3.2 million years in order to be considered ancient.

Among the most widely utilized elements for radiometric dating of rocks are argon, uranium, potassium, and rubidium since their half lives are quite long compared to those of other radioactive elements. Carbon is not utilized for dating rocks because its half-life is too short, making it ineffective.