A landscape of the Carboniferous era. [Image: https://upload.wikimedia.org/wikipedia/commons/thumb/0/0a/Bulgo_Sandstone_biota.jpg/1456px-Bulgo_Sandstone_biota.jpg]Imagine you had a Time Machine: where and when would you go to? Come with me back to Nowhere Wood, about 310 million years ago. That is long before humans, mammals or even dinosaurs existed, but frogs laid their eggs in pools, much as they do today.
Today it is hot, humid and very quiet: with no birdsong or animal noise, apart from the distant croaking of frogs.
Extinct tree ferns from the Carboniferous era. [Image: https://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Lepidodendrales_reconstrucci%C3%B3n.jpg/1280px-Lepidodendrales_reconstrucci%C3%B3n.jpg]We are in the northern foothills of an enormous mountain range, bigger than the Himalayas. It is unbearably hot and humid. We are next to a river flowing from the Southern mountains, surrounded by thin horsetails that grow up to 10 metres tall. Tomorrow, there will be a raging tropical storm and the mountains will be pounded by its violence. The rain will flow in torrents in rivers towards us.
Nowhere Wood is located just below the equator, and we are looking up at the aftermath of a series of global catastrophes, which has taken hundreds of million years to happen. Two continents collided and sent shockwaves through the land, pushing upwards to form the mountains that we can see to the South of us. We are in a valley, downstream from the mountain peaks.
Muddy water flowing in a stream. [Image: https://upload.wikimedia.org/wikipedia/commons/thumb/3/37/Uruzi_hamwe_n%27ikirere.jpg/2560px-Uruzi_hamwe_n%27ikirere.jpg]The mountain rock is soft and is easily weathered by the stormy wind and rain. Cascades of small, eroded particles surge down the mountain slopes, transported in the muddy river waters.
Mountains become tiny grains of sand settling at the bottom of the smaller rivers and streams running through and around Nowhere Wood. The streams are running from South to North, and criss-cross each other to form a network of channels.
Layers of sandstone on Nowhere Wood. [Photograph: Neil Ingram]Layers upon layers of sediment are depositing in the streams, blocking the channels. Over time, the increasing weight of sand squeezes the water out. Minerals like feldspar and mica help to cement the grains together to form sandstone. These are the cliffs that we can see today at the far end of Nowhere Wood.
Pennant sandstone was used to make flat roof tiles. [Photograph: https://www.beechfieldreclamation.co.uk/shop/paving/reclaimed-welsh-pennant/]Pennant sandstone used to be quarried to make roof tiles for the people of the town and local areas.
It is easy to think of living organisms having uncertain adventures through time and space. But the same is true of rocks, although on a much larger time scale.
[updated 14/02/2025]
1. Find out where the matter that makes up planet Earth originally came from.
2. Think about what has happened to the sandstone in Nowhere Wood since it was formed.
A forest of tree ferns. [Image: ttps://www.laterredufutur.com/accueil/la-plus-vieille-foret-du-monde-a-ete-decouverte-dans-letat-de-new-york/foret-380millions-dannees/]We are not alone in Nowhere Wood, about 300 million years ago. We are deep in a forest of tree ferns, towering above us, fifteen metres high. The damp air has a sweet and woody fragrance, heavy with spores, heavy with promise.
Carboniferous trees [Image: https://forces.si.edu/atmosphere/02_02_06.html]
The plants are silently photosynthesising, growing ever taller and adding oxygen to the air. Year after year, generation after generation.
Stages in the formation of coal. [Image: https://www.manalifelab.com/the-science]The wood in the tree stems is a new invention of evolution: no other plants have wood and fungi have yet to discover a way to eat it. This means that when the trees die and fall into the swampy wet soil, they do not decay, but stayed for thousands of years, gradually becoming compressed together to form deposits of coal.
The formation of most of our coal brought Earth close to global glaciation. [Image: George Feulner, https://www.pnas.org/doi/10.1073/pnas.1712062114]
The tree ferns took carbon dioxide from the air and locked it away as wood and coal. They took so much and the amount of carbon dioxide in the air fell so much, that the climate cooled, lead to the destruction of the tropical forests.
Today, humans have found the coal and burned it, putting the hidden carbon dioxide back into the air, re-warming the planet. No we face a global warming, not a global cooling. Perhaps, one day, Nowhere Wood will be destroyed for a second time.
Think about how interconnected the rocks, the trees, the atmosphere and the climate are. How does a change to one thing affect everything else?
Ferns are the first group of plants to develop proper roots. Think about why it would be an advantage for the early tree ferns to grow into sandstone.
Back then, the tree ferns grew through sandstone much as the smaller ferns in Nowhere Wood do today. Read more about this in another story: Climbing the walls.
Carboniferous dragonfly, with 1.5m wingspan. [image: https://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Meganeura.png/1280px-Meganeura.png]We are in Nowhere Wood, about 300 million years ago, staring at a forest of tree ferns, watching them make oxygen. Over the years, these tree ferns have made so much oxygen that its concentration in the air has risen to about 35%, (compare that with the 21% found in the 21st century).
Wildfires in Chile. [Photograph: https://globalclimatecare.in/climate-asia/f/man-made-or-nature-made-chile%E2%80%99s-forest-fire-creates-global-threat]There is so much oxygen that the lightning strikes produce frequent explosions in the air, causing forest fires. Nowhere Wood is a dangerous place to be, sometimes.
Arthropleura, a giant millipede. [Image: https://en.wikipedia.org/wiki/Arthropleura#/media/File:ArthropleuraSide.jpg]The animals are using the oxygen to grown large: some millipedes are 1.5 metres in length and 0.5 metres wide. Some dragonflies have 70 cm wingspans.
Hylonomous lizard [Image: https://commons.wikimedia.org/wiki/File:Hylonomus_BW.jpg] With all of this food available, there are opportunities for new carnivorous lizards to appear, including Hylonomus. This is one of the first creatures to have a new eggs with membranes inside, a characteristic later shown by all birds.
[Image: https://www.darwinsdoor.co.uk/feed/the-giant-arthropods-of-the-carboniferous.html] Also the flesh-eating Anthracosaurs first appeared at this time. These are the direct ancestors of the dinosaurs, that appeared millions of years later.
In Nowhere Wood, everything is connected together, in space and in time.
So many adventures in space and time, so much opportunity for the evolution of new forms. All of which depends on the formation of sandstone in Nowhere Wood.
Imagine what it was like to live in Nowhere Wood 300 million years ago. What would be the same and what would be different.
How do you think the world will change in the future?
