What's the geologic timescale? Well, the Earth is old, really old. It's so old that it's had 4.6 billion birthdays, but it doesn't like to talk about it.
People called geologists have counted up all the birthdays and made a big fancy chart to help remember them all. It's called the geologic timescale, and it's one of the most important things you need to know when you start to study geology. 4.6 billion years is a long time. Let's say this represents 100 years, or about a human lifespan.
That human lifespan is only one pixel if we zoom out to 100,000 years. We'd then need ten of those to get to a million years. To get to a billion years, we'd have to add that up a thousand times.
That's a really long time. There are so many Earth birthdays that we have to arrange them into phases. These phases are sometimes called eons. The eons are broken up into eras, which are broken up into periods and epochs.
Geologists are apparently fond of words that start with the letter E. The first eon is called the Hadean. It's about half a billion years when the Earth is just a hot ball of rock.
And the moon is forming. What's up moon? Next is the Archean.
Everything has chilled out a bit by now and the continents are forming. This takes a really long time, almost 1.5 billion years, and life is starting to form in the oceans. As the Archean is ending, that new life starts to fart out oxygen into the atmosphere.
After that is the Proterozoic, which means early life. But it really means very small life. During the Proterozoic we get the first complex cells, and the first things that are made up of more than one cell.
Proterozoic is also very long, about 2 billion years. As the Proterozoic is ending, we get the first plants and the first animals. The final eon is called the Phanerozoic, which means visible life. It started about 500 million years ago with an explosion of new and crazy-looking living things, and continues to this day. It's divided into three eras.
The first era is called the Paleozoic, which means old life. But what it really means is squiggly life, or weird, wormy life. It also means creepy-crawly life.
Mesozoic means middle life, but it really means dino life, or life that goes roar. The Mesozoic ended with a giant asteroid that killed almost everything that went roar. The third era, the Cenozoic, means new life, but it really means furry life and flappy flying life.
We also got pretty looking things that bloom. There's lots of different furry and flappy things. There's things that go blub, things that squawk, and things that go awoo. There's also new things that roar, but they're much fuzzier than the old ones.
That's the geologic timescale. Some say that humans have changed the Earth so much that we've entered a new period of geologic time called the Anthropocene. More on that next time.
Until then, keep it curious.