Geologic time of Earth

Geologic Time of Earth

Geologic time of earth is the vast period that has passed since the beginning of the Earth. The history of the planet Earth goes back as far as 4.5 billion years. It took many more years for life to form on Earth. About 3.5 billion years ago, first, living organisms were originated in the oceans. According to scientists, marine life evolved for another million years, and some later spread to land. The first to spread on land were plants, not animals. Man, compared to plants and animals, was born much later.

In typical day-to-day life, we use time frames such as hours, days, weeks, and years. Something that happened a hundred years ago is called old while something that occurred a thousand years ago is known as ancient. However, in terms of geologic time, the duration is different. There, a period of 1000 million years ago, is probably called old. Hence, this long time is difficult to interpret using ordinary time frames. Because of this, geologists use a different time scale called the geologic time scale. Here, Geologists divide the entire geologic time into different magnitude units. Simply, it is the calendar used by geologists. However, the geologic time scale is a dynamic tool, and it can always update with new findings.

Structure of the Geologic time of earth scale

In descending order, the geologic time scale divides into several subdivisions, namely Eons, eras, periods, and epochs. On this scale, the earliest events are recorded at the bottom.

The Geologic Time Scale v.5.0.

EonEraPeriodMillions of years agoKey geological and biological events
PhanerozoicCenozoicQuaternary2.58Humans develop
Neogene23.03Ice age begins
Paleogene66The rise of the mammals
MesozoicCretaceous145Extinction of dinosaurs
Jurassic201.3First birds
Triassic251.9First mammals
First dinosaurs
PaleozoicPermian298.9Formation of Pangaea
Pennsylvanian323.2Abundant coal-forming swamps
Mississippian358.9First reptiles
Devonian419.2First amphibians
Silurian443.8First upright-growing land plants
Ordovician485.4First jawless fish
Cambrian541Golden age of invertebrates
Precambrian4000Earliest shelled animals
Earliest fossil records of life
Source: The Geological Society of America and
Essentials of Geology, Frederick K. Lutgens, Edward J. Tarbuck, 11th edition


First, geologic time divides into Eons. An Eon is a substantial period. The geologic time of the Earth can divide into three Eons. Namely, Archean, Proterozoic, and Phanerozoic.

The first two Eons are commonly known as the Precambrian (4000 – 541 million years ago). It comprises the first 4 billion years of Earth’s history. This period accounted for 88 percent of Earth’s history. During this period, the Earth’s continental crust was created. Moreover, first, living organisms appeared in the Precambrian oceans. Phanerozoic is the Eon in which we live today. And it began about 541 million years ago.


Next, Eons again split into eras. The Phanerozoic Eon that we live in today divide into three main eras; Paleozoic (ancient life), Mesozoic (middle life), and Cenozoic (recent life). As the names suggest, these eras experienced a profound worldwide change in life forms.

The Paleozoic era (541 -251.9 million years ago) saw a variety of new life forms. During the early Paleozoic era, all major invertebrate groups formed in the oceans. Invertebrates are creatures without backbones such as jellyfish, worms, and mollusks. These life forms diversified dramatically. Later in this era, insects and plants migrated into lands, and the first amphibians emerged on the Earth.

Invertebrates dominated the oceans in the Paleozoic era

The Mesozoic era (251.9 – 66 million years ago) is often termed the “Age of Reptiles.” During this period, reptiles, especially Dinosaurs, ruled the Earth. However, at the end of this era, Dinosaurs and many other giant reptiles were extinct from Earth.

During the Cenozoic era (66 million years ago – present), mammals became the dominant life form. Therefore, this era is commonly known as the “Age of Mammals.” Also, this era saw the emergence of the first flowering plants.


Each era again subdivides into periods. Compared to eras, each period is distinguished by a slightly less profound change in life forms.


Finally, each period subdivides into smaller units called epochs. There are seven epochs in the Cenozoic era. Among the seven, the last three epochs are the most notable periods in the realm of human history.  During the Tertiary period, humans were genetically separated from their apelike predecessors. In the Pleistocene epoch, human evolution saw a significant change. Subsequently, the genus homo emerged on the African continent. Also, the Pleistocene epoch experienced the last ice age. During this time, 30 percent of the Earth’s surface was covered with thick glaciers. However, the beginning of the Holocene epoch marked the end of the last ice age. And this new warmer climate induces agriculture and led to the Agricultural Revolution. At present, we live in the Holocene epoch.

Time scale of Cenozoic Era

CenozoicQuaternaryHolocene (0.012 million years ago - present)
Pleistocene (2.58 million – 0.012 million years ago)
TertiaryPliocene (5.3 – 2.58 million)
Miocene (23.0 -5.3 million years ago)
Oligocene (33.9 – 23.03 million years ago)
Eocene (56 – 33.9 million years ago)
Paleocene (66 – 55 million years ago)
Source: The Geological Society of America and
Essentials of Geology, Frederick K. Lutgens, Edward J. Tarbuck, 11th edition

72 thoughts on “Geologic Time of Earth”

  1. Pingback: The Prehistoric Age and stone age

  2. Everything is very open with a really clear explanation of the issues. It was truly informative. Your site is very helpful. Many thanks for sharing. Natividad Wendel Steinway

  3. Hi there! I just wish to offer you a big thumbs up for the excellent info you have here on this post. I will be returning to your blog for more soon. Cahra Joseito Hallerson

  4. I am frequently to blogging and also i actually appreciate your content. The article has truly peaks my interest. I am mosting likely to bookmark your website and maintain looking for brand-new information. Sidonia Bent Eran

  5. When some one searches for his essential thing, therefore he/she wishes to be available that in detail, therefore that thing is maintained over here.| Jeanette Chaim Ita

  6. Hey there. I discovered your web site by way of Google even as searching for a similar matter, your site came up. It appears good. I have bookmarked it in my google bookmarks to visit then. Wrennie Jeddy Healey

  7. Thank you for the auspicious writeup. It in reality was a entertainment account it. Glance advanced to more added agreeable from you! However, how can we keep up a correspondence? Riki Kasper Carolina

  8. Ahaa, its nice conversation concerning this paragraph at this place at this weblog, I have read all that, so now me also commenting at this place.| Cecilia Guthry Narton

  9. Very interesting topic, thanks with regard to posting. Integrate what you believe into each and every area you have ever had. by Meryl Streep. Georgianne Elijah Pesek

  10. I’m impressed, I have to admit. Seldom do I encounter a blog that’s
    both educative and engaging,
    and let me tell you, you have hit the nail on the head.

    The issue is an issue that too few men and women are speaking intelligently about.

    Now I’m very happy I stumbled across this during my search for
    something regarding this.

  11. Heya just wanted to give you a brief heads up and let you know a few of the images aren’t loading
    correctly. I’m not sure why but I think its a linking issue.
    I’ve tried it in two different web browsers and both show
    the same results.

    my website – best THC vapes

  12. Hello there! This article couldn’t be written much better!
    Looking through this article reminds me of my previous roommate!
    He always kept preaching about this. I’ll forward this post to him.
    Pretty sure he will have a very good read. Thank you for sharing!

  13. Fantastic goods from you, man. I have understand your stuff previous to and you are just too
    magnificent. I really like what you’ve acquired here, certainly like what you are stating and the
    way in which you say it. You make it entertaining and you
    still care for to keep it smart. I cant wait to read much more from
    you. This is actually a great website.

  14. I was wondering if you ever thought of changing the structure of your website? Its very well written; I love what youve got to say. But maybe you could a little more in the way of content so people could connect with it better. Youve got an awful lot of text for only having 1 or two pictures. Maybe you could space it out better?

  15. Have you ever considered about adding a
    little bit more than just your articles? I mean, what you say is fundamental and everything.

    However imagine if you added some great graphics or video
    clips to give your posts more, ?pop?! Your content is excellent but with
    pics and videos, this site could definitely be
    one of the most beneficial in its field.
    Terrific blog!

  16. This is a very good tip especially to those new to the
    Simple but very precise information? Thanks for sharing this one.

    A must read article!

  17. Great post. I was checking constantly this blog and I am impressed!

    Very useful info particularly the last part
    I care for
    such info a lot. I was looking
    for this particular info for
    a very long time. Thank you and best of luck.

  18. Hey there I am so thrilled I found your web site, I really found you by mistake, while I was searching
    on Digg for something else, Anyhow I am here now and would
    just like to say kudos for a fantastic post and a all round entertaining blog (I also love the theme/design), I
    don’t have time to look over it all at the minute but I have bookmarked it and also added
    your RSS feeds, so when I have time I will be back to read a great deal
    more, Please do keep up the great jo.

  19. Have you ever thought about including a little bit more than just your articles? I mean, what you say is valuable and all. Nevertheless think about if you added some great graphics or video clips to give your posts more, “pop”! Your content is excellent but with images and clips, this website could certainly be one of the most beneficial in its field. Excellent blog!

  20. Pingback: Taxonomy of Humans - Historytz

  21. Pingback: Story of the Human Evolution - Historytz

  22. I think this is one of the most vital information for me. And i am glad reading your article. But want to remark on some general things, The web site style is ideal, the articles is really great : D. Good job, cheers

  23. Good post. I learn something new and challenging on websites I stumbleupon every day. It’s always interesting to read through articles from other authors and practice something from their sites.

  24. Hello! Do you know if they make any plugins to protect against hackers? I’m kinda paranoid about losing everything I’ve worked hard on. Any tips?

  25. obviously like your website but you need to test the spelling on quite a few
    of your posts. Several of them are rife with spelling problems and I in finding
    it very bothersome to tell the truth however I’ll
    certainly come back again.

  26. My partner and I stumbled over here different web page and thought I might as well check things out. I like what I see so now i am following you. Look forward to checking out your web page yet again.

  27. I am curious to find out what blog platform you happen to be utilizing? I’m having some small security issues with my latest site and I’d like to find something more safeguarded. Do you have any solutions?

  28. Hmm it seems like your website ate my first comment (it was extremely long) so I guess I’ll just sum it up what I submitted and say, I’m thoroughly enjoying your blog. I as well am an aspiring blog blogger but I’m still new to the whole thing. Do you have any suggestions for newbie blog writers? I’d genuinely appreciate it.

  29. Awesome website you have here but I was curious if you knew of any forums that cover the same topics talked about in this article? I’d really like to be a part of community where I can get feed-back from other knowledgeable people that share the same interest. If you have any suggestions, please let me know. Many thanks!

Leave a Comment

Your email address will not be published.