Respuesta :
In a particular context, “epoch” can refer to a particular point of time characterized by a particular event/series of events.
While “era” refers to a period of time characterized by events in a chronological order.
Thus, an “era” can encompass more than one “epoch”.
“Period” can refer to a short interval of time or a very long interval of time.
For example:
“Eon” refers to an indefinitely long time. Eon is presumed to consist of at least 2 eras.
Answer:
Eras, Eons, Epochs and Periods are the division and subdivisions of geological time scale based on the changes in the geography, geology, climate and other characteristics of the earth.
The sequence of the various divisions depends on the length of each unit of time relative to each other.
sequence of time period is as follows:
Eons > Eras > Periods > Epochs
1.Eons-The longest division of time scale which lasts for billion of years.
Geologists recognised three major Eons as:
Phanerozoic Eon (570-present)
Proterozoic Eon (2500-570 mya)
Archean Eon (3800-2500 mya)
2.Eras-eras are the subdivision of Eons which froms the second longest division of time scale. Eras can lasts for tens to hundreds miliion of years.
These are recognised as:
Coenozoic Era (66 mya-present)
Mesozoic Era (66-240 mya)
Paleozoic Era (240-570 mya)
.
3. Periods- Subdivion of time scale which is relatively shorter in time length.
periods can last for tens to million of year
Geologists have divided eras into periods-
Coenozoic Era
Quaternary-(present)- Evolution of humans
Tertiary- Mammals diversified
Mesozoic Era
Cretaceous-extiction of dinosaurus
Jurassic-Dinosaurus diversified
Permian- age of mammals
Paleozoic Era
Pennysylvian-First reptiles
Mississipian-seed ferns
Devonian-first amphibians
Slurian-first land plants
Ordovician - metazoan diversification
Cambrian-first fishes
4.Epochs- subdivision longer than an age but shorter than a period .
Epoch can last for tens of million years.