Black Earth: World of Coal Flashcards
How does coal form
Coal starts off as peat which gets buried as a sediment
When did the carboniferous period occur
360 to 300 million years ago
The carboniferous period was when what occured?
most coal formed
The coal-bearing rocks are Upper carboniferous
What did the contients and climate look like during the Carboniferous
Gondwana and Laurussian land masses formed the supercontient Pangea
There was a very wide tropical belt
What is the significance of the Carboniferous period
Hint’ coal
Coal has deposited in all geological periods since Carboniferous, but most was deposited in the Carboniferous
The question is why?
All land plants stem from
Green Algae
The Charophyceae, fresh water green algae, are closest relatives of land plants
They live in water so don’t need specilised fluid/gas transport system
Around 540Mya
What is a Vascular plant
One which has evolved a system to transport and conduct water
Early land plants (mosses, liverworts + hornworts) had waxy cuticle to prevent drying out, they lacked true vascular tissue to carry water. Instead water was captured as it ran over the plant’s surface
What is special about plants evolutionary tree
Plants are very evolutionary conservative: most major plant groups live and evolve on till today (bar two)
A Liverwort plant is an example of Bryophyte group and is one of the most primitive
What is special about this plant
Liverworts have pores of their surface but lack stomata
What is the Oldest extant group of Vascular plants and their link to the Carboniferous
Lycophytes are the oldest extant group of vascular plants
In the Carboniferous, some were forest-forming trees
What are Gymnosperms and their link to the Carboniferous
Gymnosperms coexisted early with brophytes, ferns and other seedless plants which took off in the carboniferous
Literal translation - naked seed
One of the last groups to come into existance was the Angiosperms
These were
Flowering plants which close their seeds in fruit
They radiated during the Mesozoic (dinosaur time)
What plants where highly preserved from the carboniferous and why
Fossil plants of Sphenopsides (found streamside), Lycopsids (found in water) and Ferns (found in disturbed environments) were mostly preserved
Preservation is highest on swampy ground, because waterlogging inhibits decay and the other environments are often erosional
Why did Lycopsids fossilise well
Carboniferous lycopsids kept upright by very thick bark
They were waterproof, decay-resistant, bug resistant bark, which was very thick allowing it to become fossilised through the inside then filling up with sediment
How does fossilisation occur in classic coastal swamp cyclothem
- Sea level rises, which drows the swamps and hence plants there die due to salt water
- Sand also gets washed in, rising land out of water and plants can grow again
- This changing sea level was due to the wax and wane of Glacial ice melting
So what is the reason the Carboniferous produced so much coal
What is the issue with this idea tho
Tropical swamps extensive in the Carboniferous, which lasted a long time, so lots of organic deposits
But swamps are common at many other times in history
What are Detritivores
Chop up and digest dead matter, and what is not broken down, is left to decomposers
Mostly found in litter and soil
In the Carboniferous there was no wood-eating beetles, termites, flies, ants etc, so the diversite of detritivores was far less than it is now
We can analyse different peats from now and back in the Carboniferous, to look at decomposition
What is the differences seen
More big bits relative to small bits in Carboniferous peats
Suggesting slower decomposition
And more leaves relative to roots in Carbonferous peats, also suggesting slower decomposition. This is due to many detritivores being above ground
We can look at the size of borings (holes in wood) between the carboniferous and now to look at the rate of decomposition
What does it show
There has been a large increase in the size of borings in woods between the carboniferou and now
Suggesting slower decomposition in the carboniferous
Decomposition leads to carbon being returned into the atmosphere
If rates of decompsition are lower in the carbonferous, what affect does this have
Lots of Carbon was buried but hadn’t come back to the suface to be oxidised as CO₂, which came from lignin in plants
The phosphorus from Lignin fueled productivitiy from the soil, which lead to increased carbon burial in a feedback cycle
If lots of carbon is being buried, what its expected to happen to O₂ levels
Oxygen concentration in atmosphere should rise
As other O₂ sinks are full
The current % of oxygen in the atmosphere is around 21%
What effect would there be, if this was to rise like it did in the Carboniferous
This would increase susceptibility to spontaneous burning
The Carboniferous marks increases in forest fires due to high levels of oxygen in the atmopshere - negative feedback cycle
This causes coal to increase
