#ruware

Inselberg: an isolated hill standing above an extensive plain of erosion. They are steep-sided and dome-shaped [taken to encompass rewards, bornhardts and kopjes in this syllabus)

Ruwares: isolates hill low in height (10s of m) an has a smooth convex surface. It can grow to form bornhardts. Slopes angles are usually less than 20º. Weathering will cause exfoliation and disintegration. May form elongated hills at times.

Bornhardt: Isolated steep-sided dome-shaped hill rising abruptly from its surrounding etch plain. It has a pronounced summital convexity. It can reach 300m in height and has relatively few joints except for some curvilinear sheet joints and radial joints due to pressure release. Slope angle can be almost vertical and at times, up to 80º. May contain flared slopes.

Kopje/tor: A blocky hill rising abruptly from its surroundings. It is likely to have an irregular summit, 8-20m in height and undergoes block disintegration. It is characterised by a number of correctness stacked above one another which are bounded by vertical and horizontal joints which intersect one another.

Kopjes are tropical landforms which can be explained using the DWET

Tors are temperate landforms which can be explained using Palmer and Neilson’s hypothesis

DWET

Irregular basal surface of weathering (BSW) which was determined by differential jointing pattern with the massive rock forming the comical rises and the well-jointed sections giving rise to the troughs/basins

Humid phase: Acidulated rainwater and organic acids weather the rock along joints --> Hydrolysis breaks down of feldspar into kaolin

Arid phase [climate change]: Climate becomes more arid --> less water available for deep chemical weathering + lack of vegetation cover --> erosional processes like river erosion, overland flow become more dominant and strip the overlying regolith that once covered the granite --> weathered material is being uncovered faster than it is being replaced --> BSW gets exposed onto the earth’s surface --> dilatation and pressure release --> formation of curvilinear sheet joints --> these joints are in turn exploited by other weathering processes such as salt weathering but limited chemical weathering occurs

Humid phase [climate change once again!]: Domes shed water to its basins --> slow chemical weathering takes place on the comical rise while deep weathering occurs at the basins --> down wearing and lowering of the BSW

The cycle of humid and arid phases continues --> ground surface is continually lowered and more of the BSW is exposed --> height of the reward increases and is able to reach 300m in height --> reward transforms into a bornhardt

Over time, the intersections of sheet, horizontal and radial joints intersect and provide access to agents of weathering --> bornhardt/ruware will eventually by subject to block disintegration --> formation of a castle kopje, an inselbergs with a blocky and irregular profile

Temperate tors

Linton’s Theory

Deep chemical weathering occurred on rocks underground as acidulated rainwater penetrated through the horizontal and vertical joints --> block disintegration --> corseting detached from bedrock --> denudation caused the removal of overlying weathered material, allowing correctness to be exposed on the surface as tors

Palmer and Nielson’s Theory

Dwala/Ruware. Image credit WordPress.com

[title size=”3″ content_align=”left” style_type=”default” sep_color=”” class=”” id=””]ZIMSEC O Level Geography Notes: Landforms resulting from weathering: Dwala[/title]

Known as ruware in Shona, dwala in Ndebele (Nguni languages) and whaleback in English.

An example is Domboshava where several such landforms can be found.

It is a hill or rock which is dome…

Landforms resulting from weathering

Ruware/Dwala. Image credit WordPress.com

[title size=”3″ content_align=”left” style_type=”default” sep_color=”” class=”” id=””]ZIMSEC O Level Geography Notes: Landforms resulting from weathering.[/title]

Weathering processes and usually in conjunction with other denudation processes such as water and wind erosion and mass wasting results in the formation of various landscapes.

These include:

Inse…