Difference Between Era and Period

Era vs Period
 

The time concerned is what marks the difference between era and period. The Earth may look young to us and, in fact, it is newer in comparison to other celestial formations. However, the fact remains that while studying or classifying events that have taken place long, long ago, it is impossible to talk in terms of a particular year. It is all too easy to talk about a massive earthquake having taken place in a particular year in terms of AD or BC. But much before that, and when scientists are not sure of the particular time something took place, it is better to talk in terms of a chunk of time scale. The geological time scale has been divided into categories with the largest being super eons. Super eons are made up of eons, and eons contain eras. Eras contain smaller periods, epochs, and ages. This clearly tells us that era is a chunk of time bigger than a period. Let us take a closer look.

The division of total time elapsed, since the earth came into existence, into different chunks of time periods help scientists and geologists to understand and then explain the sequence of events that may have taken place on the earth. With specific names having been given to different time periods starting from the smallest to the biggest means, it is possible for the geologists to pinpoint a particular event with a greater precision. Otherwise, there would have been no way to get to the particular year of the occurrence of an event, as one year is a very short, almost insignificant time period in comparison to bigger chunks or slabs that have been classified under this system of geological time scale.

What is a Period?

Unless there is a specific need for smaller chunks of time periods, a period is considered to be the basic unit of time in geological time scale. Whenever scientists do not have dates or even year with precision, they can conveniently talk in terms of a period. Period becomes an interval of time that allows geologists to talk about events that took place long ago.

If you are interested in dinosaurs, then you may have definitely heard of different periods such as Cretaceous, Jurassic, and Triassic. These are all periods in history that belongs to the time when dinosaurs existed in the world. Each period contains some millions of years. This period time scale is used for these times because the historians do not have a very specific time period like an exact. Also, it helps to include the whole time in which a certain variety of species existed on the Earth.

What is an Era?

The era is when two or more periods are taken together; the bigger block of time constitutes an era. Two or more eras taken together make an eon while we also have bigger clubbing of time called super eons. Remember the Cretaceous, Jurassic, and Triassic periods that we discussed earlier? When taken together these three periods are known as the Mesozoic era.

Even when historians record events, the use of periods and eras come to their help. When they describe the rule or reign of a king or an emperor, they talk about a particular period in history. For example, in the western world, the most important time divisions are BC and AD to demarcate the birth and death of Jesus Christ. In the Indian context, it is Emperor Akbar’s period or the British period, and in the Chinese context, historians talk about ages or periods of different dynasties. We have the Roman era, the Victorian era, the cold war era, the black and white era, and so on.

What is the difference between Era and Period?

In geological time scale, a year is a far too short and insignificant interval of time. Therefore, geologists and scientists make use of periods and eras to talk about events taken place in the past.

• Length:

• Period is the most basic unit of interval of time.

• An era is bigger or longer than a period.

• Connection:

• Two or more periods taken together constitute an era.

• Usage by Historians:

• Historians talk of the period when they cannot have specific dates.

• Historians make use of the era to refer to the rule of an emperor or king with specific beginning and ending.

 

Images Courtesy:

1. Earth During the Jurassic Period by Buildingme11 (CC BY-SA 3.0)
2. Paleozoic era plant life via Wikicommons (Public Domain)