Geologic time rock dating
How can you tell the age of a rock or to which geologic time period it belongs?One way is to look at any fossils the rock may contain. When you find layers of rocks in a cliff or hillside, younger rocks are on top of older rocks.This is because almost all of the oil and gas found so far is contained within these rocks.These rocks are 60 to 600 million years old, approximately.Geologists find absolute ages by measuring the amount of certain radioactive elements in the rock.When rocks are formed, small amounts of radioactive elements usually get included.The Geologic Time Scale is illustrated here to help you see the way geologists have broken down geologic time into sections, each with an interesting and fascinating name, and each containing a package of rocks deposited during a certain time period…over the world.
At a certain locality on the Earth's surface, the rock column provides a cross section of the natural history in the area during the time covered by the age of the rocks.
The Modern Geologic Time Scale, as shown above, documents intervals of geologic time relative to one another, and has been continuously developed and updated over the last two centuries.