Rocks Soils and Plants Flashcards
Define weathering.
The chemical alteration and mechanical breakdown of rocks
What does weathering convert rock to? What is that then converted to?
Saprolite then soil
Define saprolite.
In-situ weathered rock
What is another name for salt action?
Haloclasty
What is salt action? What does it leave behind?
Aka haloclasty
Growth of salt crystals in rock, push apart and separate rock
- When the salt crystals blow away/dissolve a honeycomb formation is left behind
What is the volume increase of ice compared to water?
9%
What other weathering process is very similar to salt action?
Frost weathering
Describe frost weathering. How does it sustain itself?
Frost opens up cracks in rocks when water freezes and expands, these cracks then expose more of the rock to frost weathering
What are some examples of plants weathering rocks?
Roots expanding rock cracks
Upheaval of rocks when plants disturbed
Retention of water within rocks (allowing for water/frost weathering)
Organic acid excretion from roots (or from decomposition of organic matter)
Encouraging biota to graze and disturb rocks
Name four types of chemical weathering.
Hydrolysis
Acid dissolution
Redox reactions
Chelation of polyvalent metals
What was the impact of an increase in root complexity across time?
Higher rates of weathering
Which increases with higher temp and rainfall, chemical weathering rates or mechanical weathering rates?
Chemical rates
Which increases with low temperatures and low rainfall, chemical weathering rates or mechanical weathering rates?
Mechanical rates
Which group is more susceptible to weathering, granite and rhyolite or gabbro and basalt?
granite and rhyolite
How does the impact of Specific surface area of a rock on its weathering rates perpetuate a cycle of weathering?
Weathering increases exposed surface area which increases weathering rates which increases SSA etc etc
Give some examples of ultrabasic igneous rocks.
Olivine, peridotite, basalt
What sort of elements are igneous ultrabasic rocks high and low in?
High = magnesium, nickel, iron, chromium
Low = calcium, potassium, phosphorous
What do the component elements of ultrabasic rocks mean for the soils formed from them?
Low in essential nutrients while high in damaging elements
What are zonal soils?
Well developed soils that reflect that the climate was the major soil forming factor
What are intrazonal soils?
Well-developed soils where some local factor is dominant
What are azonal soils?
Those that are immature or poorly developed
What sort of plants grow on ultra-basic intrusive rock soils?
Highly selective, endemic floras
What type of soils form on acidic intrusive rock?
Zonal soils on gentle landforms but azonal on steep landforms
What sort of soils form on ultrabasic extrusive rocks?
Zonal with good diversity
What sort of soils form on acidic extrusive rocks?
Azonal soils with poor nutrient levels
What is the difference between sandstone and shale soils?
Sandstone = acidic, free, draining
Shale = less acidic, less free, still draining
Sandstone and shale are both examples of what?
Clastic rocks
What kind of soils form from limestone? What kind of plants grow?
Alkaline soils and specialist plants
What’s the major difference in soils between Dark Peak and White Peak in the Peak District? How does this affect plants and why is that notable?
Dark - acidic moorland dominated by heather
White - alkaline grassland with rich biodiversity
Notable because the two are very close but have radically different biodiversity due to their underlying geology
What plants grow on the abandoned lead mines of the Peak District?
Metallophytes, incredibly specialised plants
Where else are metallophytes notably seen outside the UK? What metals do they live ‘on’ here?
Central African Copperbelt
- Copper and cobalt
How can metallophytes be used for profit?
Mineral prospecting as they can be indicators of mineral presence
What plant only grows on copper rich soils/ as a diamond indicator?
Viscaria
Define Phytoremediation.
Removal of minerals through uptake from the soil by certain plants
How can Phytoremediation be used to benefit the environment?
Can be used to clean up contaminated areas (from hazardous industry)
What does removal rate measure?
The rate at which a plant draws a mineral/metal from the soil it grows in
