Geologic time 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 happened a hundred years ago is called as old while something 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 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.
Table of Contents
Structure of the Geologic time scale
In descending order, the geologic time scale divides into several subdivisions, namely Eons, eras, periods, and epochs. On this scale, the earliest events recorded at the bottom.
The Geologic Time Scale v.5.0.
| Eon | Era | Period | Millions of years ago | Key geological and biological events |
|---|---|---|---|---|
| Phanerozoic | Cenozoic | Quaternary | 2.58 | Humans develop |
| Neogene | 23.03 | Ice age begins | ||
| Paleogene | 66 | The rise of the mammals | ||
| Mesozoic | Cretaceous | 145 | Extinction of dinosaurs | |
| Jurassic | 201.3 | First birds | ||
| Triassic | 251.9 | First mammals First dinosaurs |
||
| Paleozoic | Permian | 298.9 | Formation of Pangaea | |
| Pennsylvanian | 323.2 | Abundant coal-forming swamps | ||
| Mississippian | 358.9 | First reptiles | ||
| Devonian | 419.2 | First amphibians | ||
| Silurian | 443.8 | First upright-growing land plants | ||
| Ordovician | 485.4 | First jawless fish | ||
| Cambrian | 541 | Golden age of invertebrates | ||
| Precambrian | 4000 | Earliest shelled animals Earliest fossil records of life |
||
Essentials of Geology, Frederick K. Lutgens, Edward J. Tarbuck, 11th edition
Eons
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.
Eras
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.
The Mesozoic era (251.9 – 66 million years ago) is often termed as 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 first flowering plants.
Periods
Each era again subdivides into periods. Compared to eras, each period is distinguished by a slightly less profound change in life forms.
Epochs
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 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
| Era | Period | Epoch |
|---|---|---|
| Cenozoic | Quaternary | Holocene (0.012 million years ago - present) |
| Pleistocene (2.58 million – 0.012 million years ago) | ||
| Tertiary | Pliocene (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) |
Essentials of Geology, Frederick K. Lutgens, Edward J. Tarbuck, 11th edition
Pingback: The Prehistoric Age and stone age
Just desire to say your article is as astonishing. Hesther Osgood Lavena
Pretty! This was an extremely wonderful post. Thanks for providing this info. Pansie Obie Siegel
Definitely believe that which you stated. Yourfavourite justification seemed to be on the internet the simplestfactor to take note of. Quintilla Friedrich Edveh
Hello! I simply wiush to offer you a huge thumbs up for your excellent information yyou have here on this post. Elbertine Saunderson Clemen
There is noticeably a bundle to find out about this. I assume you made certain good points in options also. Ameline Gerome Barbra
There is visibly a lot to identify about this. I think you made some nice points in features also. Carmella Lorne Three
Im obliged for the blog post. Really looking forward to read more. Want more. Moselle Artus Chelton
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
This is one awesome article. Really thank you! Want more. Jacquenetta Gaspard Terena
Very nice work with your entry. Many readers may view it in the same light for sure and wholly agree with your idea. Matelda Ingrim Elmer
You made a number of good points there. I did a search on the subject matter and found most people will consent with your blog. Shelia Franciskus Teddi
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
I really like your writing style, superb info , regards for putting up : D. Cherin Redford Preiser
Hi there, yup this post is genuinely fastidious and I have learned lot of things from it concerning blogging. thanks. Aretha Keefer Steward
You made some nice points there. I did a search on the topic and found mainly people will consent with your blog. Sherye Brennen Bromley
Hi mates, nice article and nice arguments commented here, I am truly enjoying by these. Roseann Nickolaus Keel
Good day! I simply wish to offer you a big thumbs up for your great info you have got here on this post. I am coming back to your blog for more soon. Kesley Kirk Keligot
Just wanna comment that you have a very nice website , I enjoy the style it really stands out. Lanita Matty Jonna
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
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
I like this post, enjoyed this one thankyou for putting up. Tasia Rodolphe Lauri
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
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
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
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
Every weekend i used to pay a visit this website, because i wish for enjoyment,
since this this web site conations in fact pleasant funny stuff too.
Way cool! Some extremely valid points! I appreciate you writing this article and also the rest of the website is very good. Mignonne Niki Hilaire
What a nice article. It keeps me reading more and more! Marilyn Bevon Fabi
Thank you ACCEPT my blogpost comment Admin.
Thank you ACCEPT my blogpost comment Admin.
Thank you ACCEPT my blogpost comment Admin.
These are genuinely impressive ideas in on the topic of blogging.
You have touched some fastidious things here. Any way keep up wrinting.
Hi there, just wanted to mention, I liked this article.
It was funny. Keep on posting!derma prime plus reviews
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.
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
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.
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?
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!
This is a very good tip especially to those new to the
blogosphere.
Simple but very precise information? Thanks for sharing this one.
A must read article!
There is noticeably a bundle to know about this. I assume you made certain nice points in features also.
Hi my friend!
I wish to say that this article is awesome, great written and include approximately all significant infos.
I’d like to peer more
posts like this .
You should take part in a contest for one of the best blogs on the web. I will recommend this site!
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.
Can I just say what a relief to find someone who actually knows what theyre talking about on the internet. You definitely know how to bring an issue to light and make it important. More people need to read this and understand this side of the story. I cant believe youre not more popular because you definitely have the gift.
I have never read such a successful article before. Really nice blog post. Thanks.
This web site is really a walk-through for all of the info you wanted about this and didn?t know who to ask. Glimpse here, and you?ll definitely discover it.
I did a lot of research on a topic I was looking for. But the most accurate information is on this site. Congratulations on a great blog.
This is really amazing information. I follow you and your blog constantly. A very successful and effective blog site.
Post writing is also a fun, if you know after that you
can write otherwise it is difficult to write.
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.
looking into your web page repeatedly.|