Mod 3 Flashcards
What is the basis of weathering
when rock is exposed to the atmosphere, water wind and temperature decrease the size of the material to small particles that are then weathered chemically.
What is a common way that sedimentary rocks weather?
spheroidal pattern. (weather in a spherical shape)
What is exfoliation?
The breaking away of sheets of granite that are exposed to the surface.
What is responsible for breaking up huge masses of rock?
Tectonic activity and ice wedging
What can the rate of weathering be attributed to?
Amount of moisture in the environment and temperature.
Which minerals weather fastest?
The minerals formed at higher temperature will weather faster
What is apotite?
A major source of natural phosphates that are release by its chemical weathering.
Why must foresters take additional care in Karst ?
Weathering is increased drastically and soil quality is reduced as soils gets lost into the karst waterways. Water quality can be affected when harvesting residue gets washed into karst caves.
What is the most significant factor in physical weathering that leads to chemical weathering?
Increasing the surface area of material.
How does the reduction in the size of material increase weathering?
As large pieces of material are reduced in size, the surface area increases dramatically. When more surface area is exposed to chemicals, chemical weathering occurs more rapidly and soil is turned into solum.
What can be assumed about rocks with a high ferro magnesium content?
They will generally be heavier due to higher iron content.
What are some major forces of physical weathering?
- Water
- Wind
- Gravity
- Vegetation
- Temperature
- Release of internal pressure – exfoliation
- Time
Where is most basalt produced?
Under the sea in rift zones where the earths plates are separating. The formation of basalt is the main force behind plate tectonics.
What is Plutonic Rock?
Another word for batholiths. Large masses of igneous intrusive rock.
Lets re-cap the exfoliation process.
what is it?
When large masses of igneous intrusive rock are formed there is allot of pressure from the weight of the earths crust. Downward weathering and plate tectonics result in these masses being exposed to the surface and relieved of pressure. The relief in pressure results in the expansion of the material until it cracks off in sheets. This process is quickened by physical weathering.
Conversion of rock to parent material - dominant force?
Conversion of parent to soil - dominant force?
- Physical weathering
- Chemical weathering
What are the pedogenic processes?
- Additions
- Losses
- Translocations
- Transformations
What is the difference between micro and macroclimate?
- Macro Climate refers to the weather pattern that generally comes from the east.
- Microclimate refers to site specific conditions like slope position, aspect, steepness of slope etc.
What processes influence solum development?
- PM type
- Micro and Macro climate
- Terrestrial and soil organisms
- Topography
- Time
What are additions?
When material is added to soil, typically from above ground. Main addition is organic matter (Humus). Rain also adds dissolved compounds, elements and nutrients from the atmosphere.
What are the three most important things in climate development
Micro/Macro-climate
PM type
Topography
Humus is largely composed of….?
Carbon
List all types of additions
- OM
- elements/compounds in rain
- Solar energy
- Upward translocation (of salts)
- wind additions
Where do all salts originate?
Breakdown of RFMs
What are the ways that losses happen?
- Surface Erosion of colloidal organics and clays by water and wind
- Downward movement of dissolved nutrients or leeching into inaccessible soil zones.
- Losses of dissolved nutrients through evapotranspiration and volatilization. Nitrogen is commonly lost this way.
Where are salts formed? How are they formed?
Salts are formed in the soil as a result of soil transformations
When RFMs are full broken down what is produced?
Al06 and Si04
As well as whatever minerals compose the specific RFM
Ex. Magnesium, potassium, sulphur etc
Where are hot springs generally found?
In mountainous terrain where fissures run deep into the earth, heated water rises through the cracks.
What is a precipitate?
A solid product that forms out of a solution. Rfms that’s for. From magma are precipitates.
What is responsible for the weakening of rocks during chemical weathering?
When less stable RFM’s are weathered into their basic particles
(Al06 and Si04), they are removed from the crystal matrix of the rock. When the crystals no longer interlock, the structure is weakened and it becomes much easier to break apart.
Why is clay considered more stable than most RFM’s
Because it remains in the same environmental conditions under which it was formed.
Can plants use organic nutrients?
No, must be inorganic
Can organic minerals be transformed into inorganic minerals?
Yes, through the action of bacteria, organic minerals can become inorganic and plant soluble.
What is the most basic chemical weathering process?
What is its importance?
What does it depend on?
Hydration. Basically a water molecule adheres to the RFM , which reduces stability and triggers a sequence of further reactions.
Depends on presence of water.
What chemical reaction is responsible for the formation of clays, bases and silicic acid salts ?
Hydrolysis
-Co2 in water reacts with minerals directly to produce insoluble clay minerals, positively charged ions, and negatively charged ions which are made available for plant growth or further weathering.
What is the basis of oxidation/reduction reactions?
What causes reductions?
Electrons are either lost or gained depending on conditions.
- reduction reactions are generally caused by anaerobic bacteria that gain energy from the reaction.
Where would you expect to find Gleysols?
In depressional areas that receive allot of water. Bluish grey soils?
2 main products of the chemical weathering of RFM’s?
Formation of clays
Release of nutrients in RFM’s
what color is associated with oxidation?
What about reduction in anaerobic environment?
Red
Blue
What is Fe 3+ referred to?
Fer 2+?
Fe 3+ - Ferric
Fe 2+ - Ferrous
What is Carbonation?
An acid base reaction where C02 and other acids in the soil promote the chemical decomposition of rock and RFMs.
What are some acids other than Carbonic acid that contribute to soil weathering?
Oxalic Humic Citric Nitric Tartaric Fulvic Sulfuric
What is a buffering agent?
A soil that has the ability to maintain its normal pH level throughout the different seasons.
What is the connection between seasons and pH?
lower pH (More acidic) in winter due to more water and dissolved acids
Higher pH (More basic) in the summer
What is complexation?
When organic ‘ligans’ from the soil is translocated downward through the soil profile, picking up Al and Fe from the A horizon and depositing them into the B horizons as they continue to travel downward.
Typical in formation of podzols.
