Weathering, Karst, and Mass Movement.

Sediment originates from the in-situ breakdown and alteration of earth materials, which can include both rock and sediment.
Illustrated with a photo from Mildura, Australia.

Definition: The mechanical breakdown of earth materials.
Causes: The processes contributing to physical weathering include:
- Frost action: Expansion and contraction due to freezing and thawing.
- Pressure release: Reduction in pressure can cause rock to crack.
- Salts: Salt weathering occurs when saline solutions crystallize in rock crevices.
- Thermal effects: Variations in temperature can result in material expansion and contraction.
- Wetting and drying: Alternating conditions can lead to the mechanical breakdown of materials.
Example: Block field in the Yukon Territories, as presented by Trent student Stephanie Lyons.

Definition: The alteration of rock minerals that enhances their stability under local conditions.
Process:
- Involves the removal of soluble components from the mineral structure.
- The addition of hydroxyl groups, carbon dioxide, and oxygen occurs from the atmosphere.
Example: Illustrated with a photo from Lone Pine, California.

Definition: Weathering facilitated by biological agents such as plants and animals.
Impact of organisms: Roots of plants may penetrate rocks, contributing to mechanical weathering, while microorganisms can facilitate chemical changes.
Reference: Polygenic features discussed in relation to weathering types like salt weathering and frost wedging observed at Peggy’s Cove.

Definition of karst: Regions characterized by soluble rocks such as limestone ($CaCO3$) and dolomite ($CaMg(CO3)_2$).
Notable Area: The Kras region of Slovenia, comprising 43% karst landscape.
Example: Predjama Castle, also in Slovenia.

Reference to Grotta del Vento in Italy as an example of cavern systems formed through the dissolution of limestone.
Effects of CO2 on Water Chemistry:
- Increased CO2 dissolves in water, reducing pH (increasing acidity).
- Increased acidity enables greater breakdown of calcium carbonate ($CaCO_3$), allowing it to enter solution.
- If CO2 degasses from water, calcium carbonate can precipitate back into solid form.

Soil is defined as a natural body of mineral and organic matter that has changed or is changing due to climate and living organisms.

Removal of Material: Material is leached or removed from the upper portions of the soil.
Accumulate Deeply: Material accumulates at deeper soil levels.

Climate:
- Factors include precipitation levels, timing, temperature conditions, and degree-days.
Organisms:
- Includes vegetation and soil macro-organisms (e.g., earthworms) as well as soil micro-organisms that contribute to organic material decomposition and nutrient cycling.
Topography:
- Influences water movement and associated material from higher to lower elevations.
- Affects drainage conditions impacting chemical processes and decomposition of organic matter.
- Results in a sequence of different soil profiles, known as a catena, down a slope.
Parent Material:
- The type of material (e.g., bedrock, glacial deposits) on which soil develops impacts nutrient availability and weathering rates.
Time:
- The development of soil profiles occurs over time, influencing the formation process and characteristics of soils.

Soil Texture: Refers to the proportion of different particle sizes in soil; visualized through a soil textural triangle.
Soil Structure: Examines how individual soil particles group together into aggregates.

Podzolization:
- A specific soil profile development process characterized by highly leached A horizon over an organic surface layer and a B horizon that accumulates iron and humus, typically found in acidic parent material.

Hillslope systems are characterized by the input of energy and matter, where weathered materials are prone to erosion and transport.
These systems can be conceptualized as process-response systems, where the morphology of the slope is influenced by and influences operational processes.
Downslope transport is contingent on the ability of weathering and erosion processes to alter material to sizes that can be transported.

For material to move downslope:
- The gravitational force ($F{gravity}$) must exceed the combined forces of friction ($F{friction}$), inertia ($F{inertia}$), and cohesion ($F{cohesion}$).
- The gravitational component of force is dependent on slope angle.
At a defined threshold, the gravitational force will equal the total resistive forces ($F{gravity} = extstyleigsum F{resistance}$).

Equilibrium stability: The system operates in a balanced state.
Destabilizing event: A geomorphic threshold is exceeded, disrupting the balance.
Adjustment period: The system undergoes a period of adaptation.
New equilibrium: A different condition of equilibrium is formed.

Instances where balance is disrupted can include phenomena such as rockfalls and earthflows, which can lead to significant landscape alterations, such as the noted landslide that dammed the Chilcotin River on August 1, 2024.