SS Geo Notes: Weathering, Erosion, and Human Impact

A set of vocabulary flashcards covering the concepts of weathering, erosion, deposition, river features, and human impacts on soil erosion based on the lecture notes.

Weathering

The process where rocks on or close to the surface of the earth slowly break down into smaller pieces.

Minerals

The components of rocks that eventually provide nutrients in the soil for plants.

Physical weathering

The breakdown of rock caused by physical forces.

Frost shattering

A process of physical weathering in which rocks are broken up when water in the cracks freezes and expands.

Exfoliation due to unloading

A type of weathering occurring in igneous rock formed deep underground; when the heavy load on top is worn away, the rock expands and develops cracks parallel to the surface, breaking up in layers.

Chemical weathering

A process where chemicals in the air or water react with substances in the rock, weakening them and causing the rock to break up.

Carbonic acid

A weak acid formed when carbon dioxide in the air dissolves with rain water, which reacts with calcium carbonate in rocks like dolomite and limestone.

Elephant skin

The grey, wrinkled appearance of dolomite rock caused by chemical weathering that forms grooves on the surface.

Oxidation

A process where oxygen interacts with iron, causing it to rust, weaken, and crumble, often resulting in reddish-colored soil.

Onion skin weathering

A pattern of chemical weathering where the resulting layers of rock look like the layers of an onion.

Biological weathering

Weathering that results from the actions of living things, which can be either physical or chemical.

Acid rain

Rain made acidic by gases like sulphur dioxide and nitrous oxide from burning fossil fuels, which causes rocks like limestone and marble to weather faster.

Erosion

The process by which rocks and soil particles are worn away and moved elsewhere by moving agents.

Agents of erosion

Moving forces such as wind and water that pick up, break, and transport pieces of rock and soil.

Load

The material that an agent of erosion transports.

Deposition

The process occurring when an agent of erosion slows down or stops moving and drops its load.

Flood plain

The flat land on either side of a river that is covered by water during a flood.

Silt

Fine particles of weathered rocks carried by flood waters and deposited over the flood plain, making the land more fertile.

Meanders

Large bends or curves that develop in a river as it flows over flat land.

Oxbow lake

A lake formed when a river cuts through the narrow neck of a meander over time.

Delta

A fertile area built up by silt deposits at the mouth of a river where it enters the sea, such as the Nile river.

Interlocking spurs

Ridges of land that stretch out into a valley from either side, which the river flows around in its upper course.

Plunge pool

A deep pool at the bottom of a waterfall formed by the force of falling water and rock pieces scraping against the river bed.

Soil structure

Refers to how the soil particles are arranged and how well they are held together.

Infiltration

The process of water sinking into the ground, which is reduced when soil is compacted by heavy vehicles or covered by buildings.

Over-grazing

Keeping more animals on the land than there is grass to feed them, leading to the loss of vegetation cover and increased erosion.

Dongas

Deep gullies eroded along the tracks made by animals walking the same path repeatedly.

Mono-cropping

The cultivation of only one kind of crop year after year, which reduces soil fertility and makes it more erodible.

Contour planting

Planting crops in rows along the contour lines of a hill to reduce the speed of water flowing downhill and prevent erosion.