February 16, 2022

The geologic time scale will f*** you up

Okay, I’m gonna be straight with you here. This one has a high probability of fucking you up and/or making you re-evaluate your entire existence. If you are the type to use recreational drugs, I recommend not reading this while under the influence.

Here’s what we're doing today: we are going to break down the geological time scale from Earth’s formation to today. It’s going to be fun.

Supereons

The taxonomic hierarchy for the geological time scale is, starting from the top: supereons, eons, eras, periods, epochs, and ages. We’re going to ease into this by starting with the supereons. There are only two: the current one, which hasn’t been named for some reason, and the Precambrian supereon. The Precambrian supereon ended when hard-shelled creatures first appeared in abundance.

The current supereon has been going for 541 million years. The Precambrian supereon lasted 4,059 million years or a little over 4 billion years. That looks like this:

Eons

“That’s not that bad, T.L. What’s the big deal here?” you ask. We’re just getting started, dear readers. Stay with me.

Next come the eons. There are 4 of them: Phanerozoic, our current one, maps to our current unnamed supereon, and therefore also has been going for 541 million years. The phanerozoic eon likewise is heralded by when animals first developed hard shells preserved in the fossil record. The Precambrian supereon breaks into the following eons: Proterozoic (1.959 billion years long), Archean (1.5 billion years long) and Hadean (600 million years long). That looks like this:

Eras

Everyone still doing okay? Great. Things are going to start getting a little trippy now. The eons break up into 14 eras. Our current era, the Cenozoic, started 66 million years ago with the extinction of the dinosaurs. This is called, by smarter people, the Cretaceous–Paleogene extinction event and is attributed to what those same people call the Chicxulub impactor, which, in my opinion, sounds a lot cooler than “mean asteroid goes kaboom.”

Here’s what the eras look like:

See what I mean? We’re that darker blue slice at the top. That tiny dark blue slice that is so small, Google Sheets couldn’t fit a data label into it. That’s us. Us and everything else that’s happened since the dinosaurs went extinct.

Periods

Onto periods. The eras break into 22 periods, beginning 200 million years ago, at the end of the Archean eon. Our current period, called the Quaternary period, has been ongoing for less than 3 million years. The Quaternary period corresponds with the time during which recognizable hominids existed. Not homo sapiens, but hominids.

Here’s what the breakdown of the periods looks like:

Our period, since hominids first appeared, is represented by that dark blue slice at the top. Do you see it? No, you don’t, because I had to save this image as a JPG to make this email small enough to send. Out of curiousity, I exported this graph at the highest quality SVG file, uploaded it to Figma, and zoomed in to measure it.¹ At its widest point, our slice is 0.52 pixels wide. That’s it.

Hominids represent 0.05% of the Earth’s history. Not homo sapiens, just Hominids. From here out, I’m going to have to use a few different charts, just so you can SEE us. Here’s where our period fits in to the Cenozoic era:

The colors in this chart map to the same colors in the chart of all periods. That means those little yellow and red slices at the top of the full chart? Those map to the yellow and red slices dominating the chart of the Cenozoic era.

Epochs

Okay. Great. We’re doing great. Everyone just breathe. We are not insignificant specks of dust stuck in the fibers of the giant carpet of time. We matter. We’re here. Let’s look at the epochs

There are 23 epochs, starting at the end of the Precambrian supereon, 541 million years ago. Isn’t it nice to be back there, in that familiar territory where we at least accounted for 10% of time? Here’s what the epochs look like, from the formation of Earth:

Oh. Wait. I don’t like that. Let’s zoom in on only the epochs, aka time since our supereon began. Here’s that:

Hmmm. I still can’t find our epoch, the Holocene. Because it represents 0.000021% of that chart. Let’s try again. Computer, zoom in on the epochs since the Cenozoic era:

I just uploaded the SVG to Figma again. Our epoch is in that chart, in dark blue. You just can’t see it because it is 0.17 pixels wide. Let’s look at just the epochs within the Quaternary period? Computer, could you, um, make me feel a little less insignificant?

Ah, there we are. The Holocene, representing 0.5% of the Quaternary period, which in turn represents less than 4% of the Cenozoic era. The good news is, the Holocene only represents the last 11,700 years, while homo sapiens, aka us, have been around for the last 300,000 years! The bad news is, we homo sapiens are so insignificant in the grand scheme of the geologic time scale that we don’t ever get an epoch or period dedicated to us. We just kind of begin to exist at some point in the midst of the Pleistocene epoch and Quaternary period.

In fact, our current epoch isn’t defined by humans at all. It begins after the last glacial period, which concluded with the Holocene glacial retreat. It does, thankfully, have some correspondence with our existence, in that the Holocene largely overlaps with the beginning of our rapid proliferation across–and impact on–the Earth.

Ages

Alright, we made it. This is the lowest level of the geologic time scale taxa. I’m not going to sugar coat it for you, this is going to hurt a little. Here we go.

There are 102 ages, starting, like the epochs, at the end of the Precambrian supereon, 541 million years ago. Here’s what the ages look like from the Earth’s formation:

You know what? No comment. Computer, zoom in on just the Ages please?

Oh wow, no thank you. Computer, the Cenozoic era?

Oooh are we that little green slice at the top? No? We’re still the dark blue slice? I don’t see a dark blue sli- oh. Got it… Never mind. Uh, computer, if you don’t mind?

Well, good news/bad news. Good news: our age is actually more than a pixel wide here. Bad news: it's still only 1.52 pixels wide. Let’s just look at just the ages of the Holocene, eh?

There we are! Look at us! 35.9%! Not at all insignificant!! As long as you don’t consider that that’s 35.9% of the Holocene, which is 0.5% of the Quaternary period, which in turn represents less than 4% of the Cenozoic era. We matter! I bet that the beginning of the Meghalayan age, 4,200 years ago has something to do with us, right? Because we matter? Let me just look that up, and… Ah, I see. It says here that age began with a 200-year drought that impacted human civilizations. So it has more to do with the Earth’s impact on us, and not the reverse. I see. Hmmm.

But what about the anthropocene? That’s us, right??

Well, turns out, those big brain folks haven’t actually ratified the anthropocene as an official “age” in the geologic time scale. They’re working towards that. They still haven’t agreed on when exactly it begins. They have to identify a Global Boundary Stratotype Section and Point (GSSP), aka a marker within the Earth’s strata that indicates a substantial global impact of humans on the total environment. But we aren’t there yet. If or when that happens, the anthropocene could begin anywhere between 8,000 years ago, with the development of farming and sedentary cultures, and 77 years ago, with the detonation of the first atomic bomb. That would represent between 0.0000017% and 0.00017% of the Earth’s existence.

So there you have it. That’s what we, all of humanity, are. Less than one ten-thousandth of a percent of Earth’s history. Now go out there and enjoy your one wild and precious millionth of a percent of history, you glorious speck of dust!

You can find all the data from this piece in this spreadsheet and get a closer look at the graphs in this folder of images. Have fun.