Compare and contrast relative dating and radioactive dating
From beneath the sand, appears the corner of a royal monument, carved in stone.Dedicated in honor of Pharaoh Merneptah, son of Ramesses the Great, it became known as the Merneptah Stele. Most of the hieroglyphic inscription celebrates Merneptah's triumph over Libya, his enemy to the West, but almost as an afterthought, he mentions his conquest of people to the East, in just two lines.Near the banks of the Nile, in southern Egypt, in 1896, British archaeologist Flinders Petrie, leads an excavation in Thebes, the ancient city of the dead.Here, he unearths one of the most important discoveries in biblical archaeology.This uses radioactive minerals that occur in rocks and fossils almost like a geological clock.It’s often much easier to date volcanic rocks than the fossils themselves or the sedimentary rocks they are found in.Studying the layers of rock or strata can also be useful. If a layer of rock containing the fossil is higher up in the sequence that another layer, you know that layer must be younger in age. This can often be complicated by the fact that geological forces can cause faulting and tilting of rocks.
Relative dating is used to determine a fossils approximate age by comparing it to similar rocks and fossils of known ages.
Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast.
It can only be used to date fossils younger than about 75,000 years.
Typically commonly occurring fossils that had a widespread geographic distribution such as brachiopods, trilobites, and ammonites work best as index fossils.
If the fossil you are trying to date occurs alongside one of these index fossils, then the fossil you are dating must fall into the age range of the index fossil. In a hypothetical example, a rock formation contains fossils of a type of brachiopod known to occur between 410 and 420 million years.