10. Black Earth Flashcards
What’s significant about coal in comparison to other rocks?
Coal is the only combustible rock
From what era are coal bearing rocks most prevalent?
Upper Carboniferous
Does upper mean earlier or later in reference to time periods?
Later (closer to present)
What is the significance of most continents being clustered on the equator in the carboniferous period?
Extensive tropical climates
What difference is there is prevalence of plants between the Silurian and late Devonian/Carboniferous?
Plants were scarce during silurian, but becoming abundant on land from late devonian
During what era do plants appear on land?
Paleozoic
What makes a plant vascular?
The presence of xylem as a mechanism for transportation within the plants stems
What new attribute of plants first developed around the Permian period?
Seeds
What new attribute of plants first developed around the Carboniferous period?
Early vascular systems in plants
What are Charophyceae?
Fresh water green algae, closest ancient relative of land plants today!
What are the oldest group of extant vascular plants?
Lycophytes
What are lycophytes?
oldest extant group of vascular plants, i.e. first vascular plants
What two types (genuses?) of plant had developed before the carboniferous?
Charophyceae, Bryophytes
What defines Bryophytes?
- First land plants but still very tied to water
- Only some had stomata
What group of plants originated around the end Carboniferous and dominated for >200My?
Gymnosperms
What are the defining features of gymnosperms?
- Seeds
Still dominate in high-latitude regions
What 4 groups are included in gymnosperms?
Cycads, ginkgoes, gnetophytes, conifers
What are angiosperms? When did they develop?
Flowering plants
- During the mesozoic
What are the four main environments plants adapted to live in?
Dry, streamside, wet, disturbed
What environmental conditions led to the best preserved plants?
Swampy ground
What process is referred to as the ‘Palaeozoic apartheid’?
The process by which different taxonomic groups of plants would adapt for different environments and stay largely separated.
What are lycopsids?
Water and fire resistant plants with thick bark
What is a common feature of preserved lycopsids?
Preserved with a hollow centre as that rots away and the thick, strong bark is preserved
What is most coal composed of?
Bark of swamp lycopsids
What cyclical cycle reinforced coal production in tropical swamps?
- Sea levels would rise over a tree rich region, creating a layer of sediment over coal seams.
- When this water recedes, new swampy conditions give rise to more trees and coal
- Sea levels rise again etc
What two things are heavily involved in our current cycles of decomposition?
Detritovores and decomposers
How do detritovores and decomposers work together?
Detritovores ‘chop up’ dead matter, decomposers then decompose this
What are 2 broad examples of decomposers?
Fungi, bacteria
Why is so much coal made of swamp lycopsids?
Bark is made of lignin, which is very hard to break down
What is one diversity based reason why so much more coal was produced in the carboniferous period?
No/significantly less wood-eating detritovores
What 3 data results suggest slower decomposition in the Carboniferous period?
- More big bits relative to small bits in peat
- More leaves relative to roots in peat
- More undecomposed leaves
What is the significance of slower decomposition in the carboniferous period?
More time for dead matter to become coal
What is the significance of detritovore bore hole size in the Carboniferous?
Up to 40 times smaller, harder to break down matter then
What is the 4 step coal process of the carboniferous?
1) Trees with thick and decay resistant bark fall into still swamp water.
2) Few shredders and borers or detritovores to decompose them.
3) Rotting uses up oxygen in the swamp and creates an anoxic environment .
4) The anoxic environment hampers bacteria and fungi processes.
How does the ‘coal machine’ of the carboniferous increase oxygen levels?
- Lignin contains lots of C but not much Phosphorus.
- C is taken out the system by coal, but phosphorus is not really
- P Continues to fuel productivity on land and bury more carbon.
- Oxygen can rise as C levels drop
What negative feedback loop maintained oxygen levels in the Paleozoic and Mesozoic as lower than they could’ve been?
Forest fires destroying/hampering oxygen producing plants
Why did more forest fires take place after the carboniferous? What evidence do we have?
Higher oxygen levels increase probability of flash fires
- Charcoal is common from this era
What can CO2 reduction in the last 45My be mostly attributed to?
Increased mountain uplift and weathering
