Welcome to the first eon of Earth’s history, the Hadean Eon. In this blog we will explore the beginning of Earth by looking at the timeline, some key features and the subdivisions of the eon.
Future blogs will explore in detail the other eons of Earth’s history. For this blog, we will be referring to the image below as our timeline.
Overview of the Hadean Eon
The Hadean Eon is named after ‘Hades’, the Greek God of the underworld. This name was given by geologists in the 20th century due to the conditions of Earth being ‘hellish’ like the underworld.
The Hadean Eon lasts from 4.5 billion years ago to around 4 billion years ago. It lasted a cool 500 million years.
Key Features of the Eon
The Earth during this time was hellish hence being named after Hades, god of the underworld. There was extreme heat, bombardment from external planetary bodies and volcanic activity.
Earth began its formation from smaller planetary bodies within a solar nebula through the process of ‘accretion’. This is the process by which particles and smaller celestial bodies collide and stick together gradually forming larger bodies like planets, moons and stars.
It was through accretion that the Moon formed. During this eon, a Mars-size object collided with Earth. Part of this planetary body likely consolidated with Earth and part of it was thrown off into space, which eventually settled into an orbit around the Earth and formed the moon.
Later in the eon there was slight cooling of surface temperature, enough to form a primitive crust. There was also the early development of an atmosphere and possibly water.
Subdivisions
This eon sees subdivisions however they are ‘informal’ meaning they are not fully confirmed or accepted by the various industries in this field of study. Nevertheless we will explore what has been said about them.
The pink dots in the timeline above mark the subdivision points of the informal eons.
Early Hadean - 4.6 to 4.4 billion years ago
This was when early Earth was coming together through accretion, the moon formed and the surface of the Earth was covered in lava oceans.
Middle Hadean – 4.4 to 4.2 billion years ago
After a couple hundred million years of this, heat radiated into space and repeated volcanic activity released heat from the Earth’s core, the upper layers began to form a protocrust (early crust).
Late Hadean – 4.2 to 4 billion years ago
Bombardment did continue however the Earth began to stabilise in its size. Within the various layers of rock, the heavy metals sank to the core, the lighter rocks came to the top crust, the atmosphere built up and oceans began to form.
Summary of the Eon
This eon represents the beginning. The processes at the beginning of anything are often chaotic and all over the place, with a general lack of direction, a sense of just being and experiencing different things until it stabilises.
While it may seem hellish to us, early Earth conditions were beautiful and part of the process of creation. It laid the groundwork for the amazing things to come.
Conditions that were ‘Just Right’
It could be said that the conditions were ‘just right’ to support life, at least the kind of life that thrives on this planet. We don’t really know what other life forms there could be. As we will see in the next eon, early life evolved in a greenhouse gas atmosphere with no oxygen and at the bottom of the oceans. Life can form in the most extreme of conditions, so while the Earth appears to be ‘just right for life’, it’s specific for the organisms we are familiar with. What about organisms we are unfamiliar with?
Lesson to Take Away
This eon provides some key things we can take away and apply to modernity and pass onto the next generation.
Transformation Through Adversity
This eon demonstrates, in a very dramatic way, the period of growth where chaos reigns supreme. The initial periods of exploration can last a short or long while but we have to go through it. It lays strong foundations for what is to follow. Without a strong foundation built on chaos and challenges, whatever comes after is more likely to crumble.
Embrace Uncertainty and Change
We generally don’t like uncertainty and change. It goes against our evolutionary design, uncertainty and change brings the possibility of injury and death, in the wild anyway. We live in an environment where death by lion or poisoned mushroom isn’t lurking around every corner.
We can become more aware of this innate trait, increase our awareness of when this occurs for us and use our intelligence and prefrontal cortex to rise above this innate way of thinking. Embrace the uncertainty and change, it is likely we’re not in immediate mortal danger by changing jobs or trying something new.
It’s the Small Things
The Earth was built up over several million years through small changes, small bombardments of celestial bodies as well as the odd large body. It takes many small things to make big long term changes. We will see this as we go through the eons, the small changes that seem incremental at the time, have huge long term impacts on the planet and on life.
Act for Long Term Gain and Short Term Pain
Another innate trait we have as humans is to chase the immediate pleasures and avoid the immediate pains. It feels better to have something sweet now but the long term pains occur due to the buildup of these small immediate pleasures. Due to advances in medicine, the average life expectancy is increasing and so the chances that we will be alive for longer to feel the long term pains of our short term gains, is very real.
Become aware of what short term pleasures you chase (food, money, power, greed) and consider the long term pains of these choices. It is a choice. Rise above it, become aware, and use your intelligence that has evolved for millions of years, to live a better everyday life.
The Earth experienced a ‘hellish’ start to its life, and moved onto flourishing phases of being.
Further Exploration
We have explored the first eon of Earth’s history, the timeline and subdivisions of time, the features of this eon that made it special and some lessons we can take away from it.
To further your education on this topic outside of Evolution of Stuff, you can explore deeper into the process of accretion, into the other planets in the solar system and their attributes, asteroid impacts, and deeper into the features mentioned above of early earth.
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