NECO Geography 2024 Theory — Question 3

Model answer

(a) Three processes of wind erosion: i. Deflation: The removal of loose particles, such as dust and sand, from the ground surface by wind. ii. Abrasion: The wearing away of rocks and soil by the grinding action of wind-borne particles like sand and gravel. iii. Attrition: The reduction of particle size through collisions between wind-borne particles, leading to the breakdown of larger particles into smaller ones. (c) A zeugen is a type of rock formation that forms through the process of differential erosion, where softer rock layers erode faster than harder layers above them. Mode of formation: - Initial structure: The formation starts with a horizontal or nearly horizontal stratified structure, where a harder, more resistant rock layer overlays a softer, less resistant layer. - Erosion process: Over time, the softer underlying layer erodes faster (mainly by wind abrasion), undercutting the harder layer above. - Undercutting and collapse: Continued erosion eventually causes portions of the harder layer to collapse, exposing more of the softer layer beneath. - Formation of zeugen: As this process continues, it creates elongated, ridge-like formations where the harder rock forms a protective cap (mushroom-shaped) over remnants of the softer rock below, forming a series of ridges and furrows called zeugen. Characteristics of zeugen: - They appear as a series of parallel ridges and furrows. - The height varies significantly depending on the thickness of the harder rock and the extent of erosion. - They are commonly found in arid and semi-arid environments where wind erosion is a dominant force. - They are usually oriented in the direction of prevailing winds or the flow of wind-borne material. [Diagram: A simple cross-section sketch would show a lower, narrower pedestal of softer rock supporting a wider, flatter cap of harder resistant rock, with the wind-facing side more undercut than the sheltered side, giving a mushroom-like profile.]