Rock layer dating
The next layer, the Mesozoic, is often called the age of dinosaurs. Of course, dinosaurs are reptiles and that's why you won't find any until after the Paleozoic which contains the first reptiles.The Mesozoic also has the first flowering plants, birds, and mammals, though few if any birds or mammals that we know of today.
Libal holds a degree in behavioral science: animal science from Moorpark College, a Bachelor of Arts from Sarah Lawrence College and is a graduate student in cryptozoology. "How to Find the Age of a Layer of Rock That Is Surrounded by Layers of Volcanic Ash" last modified April 25, 2017.
Rock layers are usually ordered with the oldest layers on the bottom, and the most recent layers on top.
The Law of Faunal Succession explains that fossils found in rock layers are also ordered in this way.
Another way to date an ash-surrounded rock layer is by identifying the geologic era of the fossils it carries.
Life arose on Earth approximately four and one-half billion years ago.