If we can dig and mine up coal, does that mean that it was once a tree that burned down?
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Back when trees first evolved, there was nothing in the world that could digest wood. For millions of years, when trees died they would fall over and just lay there on the ground, not really rotting or anything. Then huge fires would spread, all over. Then the trees would get buried, and over time the heat and pressure turned them into coal!
That’s where coal comes from!
Coal is not the same thing as charcoal.
Dead plants which are prevented from decaying by acidic/oxygen-depleted wetland waters become peat. Peat, when buried, is compressed into coal after millions of years of heat and pressure underground (which drives off the volatiles, leaving only the carbon).
Coal used to be trees (or other plants), but they didn’t burn down; they were submerged, then buried.
There *is* such a thing as fossilized charcoal caused by ancient forest fires, but that’s different. It’s called [fusain](https://en.wikipedia.org/wiki/Fusain), and doesn’t generally form massive seams like coal does (as it’s created by individual events instead of a wetland building up a thick layer of buried plant matter over hundreds/thousands of years).
No, they weren’t burned above ground. If that happened, it would be ash, not coal. Coal is kind of like charcoal. You make it by making the wood really hot, but with no oxygen, so it can’t actually catch on fire. The carbon doesn’t burn, it’s kind of purified.
Coal formation is similar, but the heat comes from the pressure of being buried under tons of dirt and rock.
At least, that’s how it seems to me. I’m not an expert.
Coal is basically old dead plants that have been buried and slightly heated up. It’s not something that previously burned down, most coal comes from plants that were in swampy environments.
Over time the dead vegetation builds up, eventually it gets buried. It then gets pressed together and will usually be heated up to some extent. How much heat it’s exposed to will lead to different types of coal.
Peat is the predecessor to coal. It used to be burnt for fuel regularly. If you look up a peat bog you can see how things kind of started.
In a way coal is very similar to charcoal. Charcoal is made by heating wood in an extremely low oxygen environment. The lack of oxygen means the carbon isn’t consumed in flames. Rather the volatile compounds and water is driven off leaving mostly carbon behind for us to burn later in normal air.
Coal is made deep in the earth. Where intense heat and pressure do much the same thing. The all that pressure and heat causes everything but the carbon compounds to leave the area and compresses them into a dense chunk of carbon.
So the prehistoric tree didn’t burn down. Rather it and many many many others fell over and got buried over millions of years. As it got deeper and deeper into the earth it went through the process I described above.
Most of the earths coal was formed during a period called Carboniferous. During this time there were trees, plants, insects, fish and animals (a lot of early amphibians – it’s also know as the Age of Amphibians) but microbes that could break down cellulose and lignin in trees hadn’t really evolved yet.
Trees just piled on top of each other, not really decaying like they do now. The climate then was quite warm and wet, there were vast forests that covered much of the land.
Towards the end of the period there was an extinction event due to climate change. The earth cooled, water levels dropped and glaciers started to form. The climate became cool and dry. This caused what is known as the Carboniferous Rainforest Collapse – basically large swaths of these forests died.
During this period the continents were also being pushed together to form Pangaea. Mountains were being formed while also pushing down adjacent crust – this formed large basins and valleys. These filled with all that dead plant matter and eventually were compressed/pushed farther under the earths surface. This material was “cooked” by the heat below the earths surface over a long period of time which eventually turned into coal.
What missing from the discussion is the carbon in coal has not been in the atmosphere for millions of years. And it has accumulated toxic elements that are released as well (sulfur & mercury).
The heavy mercury content of large game fish in the oceans is from burning coal.
Coal is basically solid oil. Stuff doesn’t need to burn to be turned into coal. You’re probably thinking of charcoal which is not the same, but is also used as fuel for things like bbq’s so it’s understandable
It’s theoretically possible that there are some are some burned up trees mixed into coal deposits. But coal forms from trees and plants even if they just die and fall over and get buried.
It kinda looks like charcoal but coal isn’t “burnt” .
No, it didn’t burn.
In the carboniferous period 360 Mya to 300 Mya is when the plants that became coal lived. These were plants that lived in swamps. Bacteria and fungus had not yet evolved to eat these plant corpses. The dead plants piled up, landed in water, got covered in sediment, and over the next few million years it got compressed into a solid chunk of carbon that we call coal today. It also has lots of impurities from the ground.
Charcoal is different. Charcoal is what is created when you heat up wood in a low oxygen environment. The hydrogen based compounds in the wood evaporate out, leaving behind a very porous chunk of carbon. Industrially produced char coal also usually has lots of oils left over in it from the wood.
Oil was also produced in the carboniferous period, but rather than plants, it’s from the corpses of algae and plankton that build up on the ocean floor, was buried by sediment, and squeezed into a mix of hydrocarbons.
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