This section will explore some of these methods in more detail, focusing on those most commonly used in human evolution research.
A large change in the plants and animals is required to identify a new geological period.
Based on data at obtained from.
If the rock we are studying has several types of fossils in it, and we can assign time ranges to several of them, we might be able to narrow the time range for the age of the rock considerably.
The chemical composition of this glass material is unique to each eruption, like a fingerprint.
Together, 40K- 40Ar and 40Ar- 39Ar are extremely useful methods to date fossils and archaeological sites relevant to human origins in eastern Africa, because that area of the world has been highly active volcanically for millions of years.