Study Geography notes on Geomorphology for Secondary. Useful for revision, homework, and exam preparation in Zimbabwe.
A free account is needed to download. Sign in or create one
This is the Geography notes. It is a free notes for revision.
Geomorphology - It refers to the study of landforms and the processes which bring about their existence. The processes include - Weathering - Erosion - Mass movement Weathering Weathering is the disintegration and decomposition of rocks, through contact with the Earth's atmospheric gases, biota and waters which occurs in situ, or "without movement". Here the term disintegration excludes chemical processes while the term decomposition includes chemical processes therefore there are Two types of weathering. That is physical weathering and chemical weathering Physical weathering - physical weathering is the disintegration of rock and soil aggregates through direct contact with atmospheric conditions, such as heat, water, ice and pressure, by physical (mechanical) processes acting primarily on pre-existing fractures (e.g. joints, cracks between mineral grains); this process reduces size of fragments according to rock and soil structure (producing grains, crystals, blocks, slabs, etc.), without a change in mineral composition of the resultant fragments. Types of physical weathering Thermal stress/ shattering/insolation weathering Thermal stress weathering results from the repeated expansion and contraction of rock caused by temperature changes in rocks containing minerals with different thermal conductivities. The differential rates of expansion and contraction repeated several times will result in stress being induced within the rock causing disintegration. For example in rocks such as granite with the minerals mica ( dark) coloured and quartz ( brightly coloured) heating of such rocks by sunlight or fires causes expansion of their constituent minerals at different rates. As some minerals expand more than others, temperature changes set up differential stresses that eventually cause the rock to crack apart. Because the outer surface of a rock is often warmer or colder than the more protected inner portions, some rocks weather by exfoliation which is the peeling off of outer layers of the rock like an onion. This process is sharply accelerated if ice forms in the surface cracks. When water freezes, it expands and increases its volume by 105 of its original and this induces stress in the rocks, disintegrating huge rock masses and dislodging mineral grains from smaller fragments. 1