Module 2 Flashcards
What are some examples of normal siliceous rocks in NZ?
- Greywacke
- Argillite
- Schist
- Granite
What soils are classified as azonal soils?
Recent soils from alluvium, recent soils from volcanic ash and skeletal soils in steep land.
The principal effect of biological activity in the soil is what?
The respiration of CO2 by plant roots and microorganisms increasing the acidity of the soil solution by producing carbonic acid.
Name 3 ways topography affects soil formation
- The effect of the slope on soil depth
- Modifying effects of climate
- Influencing soil moisture regimes
What are the processes of soil formation?
- Freezing/thawing
- Mechanical abrasion
- Wetting and drying
- Translocation
- Hydrolysis
- Leaching
- Chelation
- Gleying
What are igneous rocks formed from, and what are they the source of?
The cooling of molten magma, source of primary minerals.
What are sedimentary rocks formed from?
The burial and compaction of weathering products and resistant primary minerals.
What are metamorphic rocks formed from?
Deeper burial and heating of weathering products and resistant primary minerals.
How are minerals formed?
When primary rocks or tephras weather, both physically and chemically, secondary minerals are formed. The rate of weathering is dependent upon the chemical reactivity of the mineral.
How are sedimentary rocks formed?
By the accumulation of sediment in air or water. The sediment becomes hardened or lithified with time and is turned into rocks.
What are the four major physical properties that are used to describe each soil horizon?
- Colour
- Texture
- Consistence
- Structure
What is consistence influenced by?
Texture, water content, clay mineral composition and organic matter content.
What is plasticity?
The ability to change shape continuously under the in fluency of an applied stress and to retain the impressed shape on removal of the stress.
What is soil structure?
Naturally occurring arrangement of soil particles into aggregates that result from pedogenic processes.
What is a soil horizon?
A soil horizon may be defined as a layer of soil, approximately parallel to the soil surface, with characteristics produced by soil-forming processes.
