Paleo – A Tale of Ages

Once upon a time, there was a ball of molten rock, orbiting a small star in one arm of a galaxy that resembles many of the millions of galaxies that fill the universe.

Our best guess is that our tiny solar system is between 26 to 28 thousand light years from the centre of our galaxy. It would take a light beam this amount of time to reach us from the Galactic Centre. Our solar system, located in what is known as the Orion Arm of our galaxy, rotates around this Galactic Centre. The Galactic Year is the time it takes us to complete one complete orbit. This is believed to be between 200 and 250 million of our Earth years.

PALEO – A TALE OF AGES, is the story of a tiny planet known with affection as Gaia to some of her inhabitants. She formed as she orbited her Sun, who was much younger in those days. We will begin our tale some 4.5 billion years ago (4500 million years). We will follow Gaia’s journey through periods of intense heat, and through periods of intense cold. From Snowball Earth, to our Blue Planet, Gaia has changed and transformed herself again and again. During this time, extraordinary creatures swam in her oceans, and have walked upon her continents. Amazing plants have grown up transforming not only Gaia, but her atmosphere too.

This book for children, and maybe adults too, takes us on a journey through time… Each double page will focus on an event or geological era. This book will be serialised, with a new double-page to appear every week over the next six months. When it is complete, it will be available to purchase from this website as a digital book.

Let us take a deep breath then, and return to the ancient times. Hush! For it is now 4.5 billion years ago, and on the Orion arm of our galaxy, a new Earth is being born…

C H A P T E R  O N E

A long, long time ago, in fact, around 4.6 billion years to be precise – a vast molecular cloud of gas and dust collapsed under the force of gravity. This led to the formation of our Sun and a swirling disk around it. This “solar nebula”, consisting of elements such as hydrogen and helium, spun upon its axis. There were traces of heavier elements too, like carbon, oxygen, and iron. As these tiny specks collided and stuck together, they formed larger particles. Known as planetesimals, these ranged in size from a few centimetres to kilometres. Collisions between them took place too, and little by little they grew and grew through a process called accretion. Over time these became known as protoplanets.

With time, these protoplanets grew larger and larger. And as they did so, they began to heat. Between radioactive decay on the one hand and gravitational compression on the other, the interiors of these protoplanets finally melted, causing the heavier elements such as iron and nickel to sink towards the centre, forming a dense metallic core. The lighter components migrated towards the surface. This process took place over millions of years before Gaia was fully formed. But traces today remain in her core, her mantle, and her crust.


C H A P T E R  T W O

During the early stages of Gaia’s formation, our solar system experienced a period of intense bombardment from outer space. The Late Heavy Bombardment is thought to have occurred between 4.1 to 3.8 billion years ago. During this period, debris from the formation of the solar system bombarded the inner planets, including Gaia. This bombardment likely transformed her surface and her atmosphere – bringing in water and organic compounds.

Before this, however – and one of the most significant events in Gaia’s creation – was the formation of our Moon. Some believe that “Theia”, a proto-planet the size of the planet Mars collided with Gaia. This impact caused a mass of debris to fly up into orbit around Earth. This eventually coalesced to form our Moon. This event not only contributed to the formation of the Moon but as we shall see, would have profound effects on the evolution and the climate of Gaia 


C H A P T E R   T H R E E

From the time of Gaia’s formation to the earliest rocks, we span a period of some 600 million years – the same time as from the Cambrian to the present day. Geologists refer to this period as the Hadean, named after Hades, the Greek god of the underworld, because it was so fiery.

If the earth formed 4.6 billion years ago, about 40 million years later, Theia collided with Gaia, forming our planet and the Moon. It then took Gaia 100 million years to form her rocky Basaltic crust. By 4.4 Billion years ago, there was not only a crust but there was water too.

How do we know there was water? Ancient minerals called zircons have been found in the rocks in the Jack Hills in Australia. More than half of the ancient zircons which have been tested, reveal the presence of water from a range of different environments. Some contain signs of rocks weathered by water to form clay. Others suggest dissolved crystalline minerals which form rocks in lakes or oceans. Others suggest water reacting with rocks rich in iron and magnesium.

Where did this water come from? Comets, it is believed, brought water from afar to the Earth.

So what is the Hadean? An Earth with volcanoes, oceans, and an early Moon – Gaia’s sister. There is no life that we know of as yet. Just a cooling planet. But one that is already evolving…

C H A P T E R  F O U R

The Hadean gave way to the Archean. Spanning from 4.0 billion to around 2.5 billion years ago, this period saw several massive transformations of Gaia.

During the Archean, the Earth’s basaltic crust formed. With lava spilling out of volcanoes and then cooling, Gaia’s early crust formed. This led to the development of the first continents, and in turn, the stabilisation of landmasses.

The Archean is also believed to be when life first emerged on Earth. Although direct evidence is scarce, the presence of fossilized microorganisms in Archean rocks suggests that simple life forms, such as bacteria and “archaea”, may have existed as early as 3.5 billion years ago.

Although some traces of oxygen may have been present from exposure of the inner crust, the Archean signalled huge changes in the atmosphere. At the beginning of the Archean, Gaia’s atmosphere was different from today’s. It was dominated by gases like carbon dioxide, methane, and ammonia – there was no oxygen. The presence of liquid water on the surface allowed for the formation of oceans and it was here the first life formed. These “archaea” learned to produce oxygen. It is this first life that transformed Gaia’s atmosphere into one rich in oxygen.

It is this oxygen that makes life as we know it possible.



C H A P T E R  F I V E

Oxygen. A colourless gas. In the beginning, there was no atmospheric oxygen. Yet, as the first billion years of Earth’s history slipped away, certain organisms evolved an early form of photosynthesis, so producing oxygen as a by-product. It is curious to think of oxygen as a waste product of these early organisms. But that is what it was. 

The Hadean was a hostile environment – with high levels of volcanic activity, minimal oxygen, and extreme temperatures. In such conditions, early forms of microbial life still managed to thrive in shallow, sunlit, and nutrient-rich environments such as tidal flats, coastal areas, and shallow marine environments. Amongst these were the Cyanobacteria. These lived in clumps formed of mats of bacteria, which we know as Stromatolites.

The formation of the stromatolites involved the metabolic activities of these cyanobacteria, which precipitate calcium carbonate or, equally, bind sediment particles. This process leads to the accretion of layers over time. Such microbial mats provided a stable base for subsequent layers to accumulate, resulting in the laminated structures seen in stromatolites. Our drawing for this chapter shows a slice through one of these, layered, folded structures.

The “oxygenation” of the atmosphere – the Great Oxidation Event – occurred approximately 2.4 billion years ago and resulted in a significant rise in atmospheric oxygen levels. The presence of stromatolites and other oxygen-producing organisms contributed to the accumulation of oxygen in the atmosphere, transforming Earth from an oxygenless (anaerobic) environment to one with oxygen. This event – possibly one of the single most important in the extraordinary story of Gaia – would enable all future plants, animals, and fungi to have the oxygen they would need to respire. 

C H A P T E R   S I X

Snow-ball Earth. We now move forward to a time when Gaia was being warmed by a weak sun. Scientists think the Sun was 6% weaker than the sun we know today. During the “Cryogenian” period (720 to 635 Ma), several lines of evidence point to (at least) two “Snowball Earth” episodes when ice extended from the Poles to the Equator. These global-scale glaciations represent perhaps the most marked climate changes in Gaia’s history.

By this time a super-continent called Rodinia had formed. This was a desert-like landmass at the Equator, with barren plains stretching endlessly toward the horizon. Rodinia was drenched in a never-ending tropical rain that slowly ate away at the rocky mass.

Rodinia was the catalyst for a number of events that would influence Gaia’s journey. It was the first supercontinent in which all of Gaia’s landmasses were united. It was also located at the equator. Since continents reflect more sunlight than oceans, some think that Rodinia caused Gaia to absorb less heat from the sun than previously. The tropical rains that eroded the rocks exposed minerals that reacted with the carbon dioxide in the air, so reducing the level of greenhouse gases in the atmosphere.

These events led to a cooling process that would result in Gaia being covered by ice. For millions of years, Gaia was a white planet, truly a “Snowball Earth”.

Copyright all Images and Text © 2024 Peter Jeffs. All rights reserved

If you have enjoyed this, please visit our Pale Blue Dot Fiction page, to discover more work by ecological writers and artists, Irene Isis, and myself, Pete Jeffs. Our next instalment will be in one week!