Grade 9 Geography: Earth's Surface Forces and Sustainable Resource Use

Vocabulary practice flashcards covering earth surface processes (weathering, erosion, river features) and sustainable resource management principles from the Grade 9 Geography lecture.

Weathering

The breaking down of rocks and soil by weather, occurring as a very slow process that takes place over millions of years.

Physical weathering

A type of weathering where physical forces, such as frost and temperature fluctuations, break rocks apart.

Chemical weathering

A weathering process in which chemical changes alter the composition of rocks, making them weaker.

Biological weathering

The breakdown of rocks caused by living organisms, such as plants and animals.

Freeze-thaw action

A physical weathering process in which water collects in rock cracks, expands by $9\%$ upon freezing, and exerts pressure on the crack walls until the rock breaks after multiple cycles.

Exfoliation

Also called onion peeling; a physical weathering process in arid areas where daily temperature variations exceeding $30^\circ\text{C}$ cause rocks to repeatedly expand by day and contract by night, peeling off outer layers.

Carbonation

A chemical weathering process where rain containing $CO_2$ forms carbonic acid, transforming limestone ($CaCO_3$) into soluble calcium bicarbonate ($Ca(HCO_3)_2$) that washes away.

Oxidation

A chemical weathering process where oxygen-bearing water contacts iron in rocks to produce reddish iron oxide (rust), weakening the rock structure.

Hydrolysis

A chemical weathering process where water reacts with silicate minerals, turning the feldspar in granite into soluble clay that washes away and causes the rock to crumble.

Lichen

An organism consisting of algae and fungi living together that attaches to rocks, producing acid to chemically decompose the rock at a rate of roughly $1\,\text{cm}$ every $100$ years.

Erosion

The combination of rock weathering and the transport of loosened material away from its source by water, wind, or ice.

Deposition

The process by which eroded sediment is ultimately dropped or accumulated in a new location, forming features such as beaches and sand dunes.

River load

The sediment carried by a river—including sand, stones, and silt—which gives the water a muddy appearance.

Vertical erosion

Downward erosion common in the upper course of a river, where fast-moving water carrying boulders cuts deep, steep-sided valleys.

Waterfall

A sudden vertical drop in a riverbed formed when soft rock beneath a resistant hard rock layer erodes faster, creating an overhang that eventually collapses into a plunge pool.

Canyon

A deep, steep-sided valley formed by sustained downward river incision that is characteristically straighter than a gorge.

Meander

A large sweeping river bend formed by continuous erosion along the fast outer bank and deposition along the slower inner bank.

Ox-bow lake

A U-shaped body of water created when a river erodes through the narrow neck of a meander loop to take a direct course, isolating the previous bend.

Meander scar

The dry, indented impression remaining on a floodplain after the water in an ox-bow lake has fully evaporated or dried up.

Sustainable resource use

The practice of consuming resources at a rate that allows them to replenish and last for an extended period without being depleted or destroyed.

Unsustainable resource use

The exploitation of natural resources at a speed faster than their natural replacement rate, resulting in depletion, damage, or exhaustion.

Resource management

The strategic planning and regulation of resource consumption to ensure availability and advantages for current and future generations.

Sustainable fishing

Harvesting marine life at a threshold that permits fish stocks to continuously reproduce and maintain viable populations for future harvesting.

Fishing quota

A legal limit established to restrict the maximum volume or weight of fish permitted to be harvested within a designated period.

Marine protected areas

Designated zones in the ocean where fishing and other human disturbances are strictly limited to safeguard delicate habitats and foster fish reproduction.

Southern African Sustainable Seafood Initiative (SASSI)

An organization that educates consumers and guides responsible seafood choices through color-coded status lists.

SASSI Green list

A classification tier identifying fish species that are considered sustainable and generally safe to buy.

SASSI Orange list

A classification category of seafood that consumers should avoid or purchase with caution due to concerns like over-fishing.

SASSI Red list

A category comprising threatened or legally protected marine species that consumers must refrain from purchasing.

Over-grazing

An unsustainable condition where excessive livestock feed on land for prolonged periods, halting pasture regeneration and triggering soil erosion and desertification.

Rotational grazing

A sustainable grazing method in which livestock are cycled across different enclosed pastures to provide rested grass sufficient time to recover.

Strip grazing

A grazing strategy that confines animals to small subdivided paddocks using movable electric fences before relocating them to new segments.

Fodder

Stored plant food—such as dry grass or silage—supplied to livestock during periods when natural pasture is scarce, notably in dry winters.