The geologic time scale is divided into periods, which are then divided into epochs, which are further divided into ages. For example, the time of the dinosaurs lasted 3 periods (Triassic, Jurassic, Cretaceous), each period had 3 epochs (late, early, middle), and each age fit into one of those. Many epochs have more than 1 age associated with them.
As for the basis for differentiating the eras, I'm not so sure. The only one I can say for sure is the end of the Cretaceous, which is when the dinosaurs suddenly became extinct due to a meteor impact. I think the divisions are based on significant, global-scale events that changed the world.
from oldest to youngest the systems are
Precambrien
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
Triassic
Jurassic
Cretaceous
Palaeogene
Neogene
Quaternary
The Geologic Time Scale is divided up by four major intervals. In order from Largest to smallest: Eons are the largest time frame covering hundreds of millions of years. Eons are divided into smaller time intervals known as Eras. Eras are subdivided into Periods. Periods are broken into finer subdivisions known as Epochs.
The geologic time scale shows the timing and relationship of events that have occurred throughout Earth's history.
Geological Time Scale.
epoch
It measures the age of a fossil.:)
Eras are subdivisions of larger units of geologic time called eons.
they all connect
what is the basis on which subdivisions are made
The geologic time scale.
Geologic Time. It's called the Geologic Time Scale.
The Geologic Time Scale is divided up by four major intervals. In order from Largest to smallest: Eons are the largest time frame covering hundreds of millions of years. Eons are divided into smaller time intervals known as Eras. Eras are subdivided into Periods. Periods are broken into finer subdivisions known as Epochs.
The Geologic Time Scale is divided up by four major intervals. In order from Largest to smallest: Eons are the largest time frame covering hundreds of millions of years. Eons are divided into smaller time intervals known as Eras. Eras are subdivided into Periods. Periods are broken into finer subdivisions known as Epochs.
Precambrian is the largest division of the geologic time scale.
Phanerozoic is the eon which geologic time scale means visable life.
The Precambrian
in the scope of geologic time, how significant is the presence of humans?
Cenozoic