How is the geologic column used in relative dating
(Walker and others, 2018) The geologic time column as we know it developed in the early 19th century.
An older scheme had used Primary (oldest), Secondary, Tertiary, and Quaternary (youngest), and the new scheme retained Tertiary and Quaternary but replaced the others.
Rocks take millions of years to form, and so by looking at the layers of rock and measuring their age, we can figure out what was happening in that area of the earth all those years ago.
All of this and much more was determined by studying and analyzing the rocks we can see along the walls of the Grand Canyon.
We can do this all over the world and make amazing discoveries about the history of our planet.
The duration of each eon increases substantially from left to right.
The black and white bars to the left in the Cenozoic and Mesozoic are the magnetic time scale, which we will see later in the course.