Degradation Processes: Weathering and Soil

Just to review a few things…

Weathering: Process by which rock begins to come apart.

Erosion: The weathering and transportation of material.

1. Physical Weathering: Breaking up of material into smaller pieces (mechanical).

2. Chemical Weathering: A change in composition through a chemical reaction with water or weak acid.

Types of Soil

• Latosols: Tropical red earth; high precipitation and heat; reddish colour; agriculture poor due to leaching; found near equatorial.

• Podzols: cool, wet temperatures; ash coloured top soil; associated with coniferous forests; constant leaching; needles cause acidity and cool temperatures decrease decomposition; found in west coast of BC.

• Luvisols: Cool, dry temperatures; long winters with short growing seasons; gray top soil with clay in B horizon; found in Interior of BC; associated with smaller trees; need organic material to assist agriculture.

Types of Soils (Continued)

• Brunisols: occur in regions between podzols and luvisols; not as much clay as luvisols or as much iron/ aluminum as podzol; found in Kootenays and along Yukon border.

• Chernozemic: Black/ dark brown soil; little rain so little leaching; best soil for agriculture; cold winter and hot summer; found in Prairies; wheat.

• Sierozems: gray, desert, rocky and sandy; hot temperature, little rain; sparse vegetation (xerophytes); found in desert regions.

• Tundra: cold, dry (rain usually falls as snow); mosses and lichens dominate vegetation; poor agriculture; soil usually permafrost.

• Alluvial: soils created by deposition along rivers; good for agriculture since there are a lot of nutrients in them.

Types of Soil Degradation

1. Desertification: lack of water

2. Salinization: too much water

3. Soil Movement:

a. Creeping- expansion and contraction of soil

b. Falling- material on steep slope falls (talus cones)

c. Sliding- downward movement of a uniform material

d. Flowing- downward movement of material that behaves like a fluid.

The Water Cycle

The Water Table

Water Table Terms

• Zone of Aeration: The area above the water table that contains air and water.

• Zone of Saturation: Area below water table that is saturated due to water being pulled down.

• Water Table: Ground Water; It rises and falls throughout the year..

• Aquifer: Rock layer that can store a lot of water

• Porosity: Amount of spaces in soil.

• Permeability: How fast water can pass through rock layers.

Ground Water:

• The water held in pore spaces in the soil and unconsolidated materials below the surface.

• Due to the decay of plant material, the groundwater tends to be fairly acidic. As a result, ground water is effective at weathering limestone and creating Karst topography.

• As groundwater moves through limestone, it slowly dissolves the rock (creating pits and hollows on the surface).

• Streams can disappear underground and this contributes to the creation of caves.

Ground Water Creates Karstlandscapes

• Stalagmites: Limestone that grows as a mound in a cave.

• Stalactites: Limestone that grows down from a cave roof (like an icicle)

• Pillars: When the two join together.

• Sinkhole: When a cave grows and the overlying land collapses.

• Polje: these are formed from the collapse of underground caverns or rivers.Stalagmites

Stalactites

Pillars

Sinkhole

Polje