We talked about relative dating of rocks and how scientists use stratigraphic succession to compare the ages of different rock layers.
But did you know that we can also date a rock with a fossil?One outcrop shows layers from one geologic time period, while the other outcrop represents a different time. Can he put the pieces together to make the story more complete? Let's find out how scientists deal with this common problem by using the fossils inside the rocks.Back in 1793, there lived a land surveyor named William Smith.Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old.To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.We no longer use this system of dividing geologic time.Since that time the system for naming the periods has been constantly changing.Each period name is a link to a web page with details about the geology, climate, plants and animals of that time.to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth.The table of geologic time spans presented here agrees with the dates and nomenclature proposed by the International Commission on Evidence from radiometric dating indicates that the Earth is about 4.570 billion years old.The geological or deep time of Earth's past has been organized into various units according to events which took place in each period.