Chapter 5- Weathering Soils Flashcards
What is weathering?
The process by which rocks are broken down into smaller particles.
What are the two main types of weathering?
Mechanical weathering and chemical weathering.
True or False: Mechanical weathering involves the physical breakdown of rocks without changing their chemical composition.
True
What is the primary agent of chemical weathering?
Water
What is the process where rocks and minerals dissolve in water?
Dissolution
Which type of weathering involves the action of plants and animals breaking down rocks?
Biological weathering
What are the three main types of soil particles?
Sand, silt, and clay
True or False: Sandy soils have large particles and drain water quickly.
True
What type of soil particle is the smallest and has the best water retention?
Clay
What is the process where soil particles are carried away by water or wind?
Erosion
Which horizon of the soil profile contains the most organic matter?
O horizon
What is the layer of soil where roots grow and nutrients are taken up by plants?
Topsoil
What is the process where minerals are dissolved in water and taken up by plant roots?
Nutrient uptake
What is the measure of the acidity or alkalinity of soil?
Soil pH
True or False: Soil pH affects the availability of nutrients to plants.
True
What is the term for the process where soil becomes compacted and loses its ability to hold water and nutrients?
Soil compaction
Which soil texture has the best water retention and nutrient availability?
Loam
What is the process where soil particles settle into distinct layers based on size and density?
Soil stratification
True or False: Soil fertility refers to the ability of soil to support plant growth.
True
What is the process where soil nutrients are replenished through the decomposition of organic matter?
Nutrient cycling
What is the term for the removal of soil nutrients faster than they can be replenished?
Soil depletion
Which type of soil has the highest nutrient content and best water retention?
Humus-rich soil
True or False: Soil erosion can lead to loss of topsoil and decreased soil fertility.
True
What is the process where soil particles are carried downhill by the force of gravity?
Mass wasting
Pressure release
Removal of overlaying rock allows expansion and fracturing.
(Exfoliation domes)
Frost action
Mechanic effect of freezing (and expanding) water on rocks. Frost wedging and frost heaving.
Other types of mechanical weathering
-plant growth (tree roots)
-thermal variation (large temperature changes fracture rocks by repeated expansion and contraction)
-salt pressure
-Burrowing animals
A horizon
Dark colored, rich in organic matter and high in bio activity
E horizon
Zone of leaching; fine grained material removed by percolating water
B horizon
Zone of accumulation; clays and iron oxides reached down from above; forms hard pan in wet climates
C horizon
Partially weathered bedrock
Residual
Transported
-weathering of underlying rock
-brought in from elsewhere wind-transported soil is called Loess
Soil composition
Determined by parent rock comp evolves with time and chemical weathering.
