Geomorphology Flashcards
(25 cards)
what are bedding planes?
The planes separating each layer or strata. Horizontal layers of rock where sediments have been deposited
how do horizontally-layered rocks erode?
The strata of these landscapes are uniformly resistant to erosion, which means: Each of the layers of rock erode at a similar rate.
Briefly describe Hilly landscapes
refer to: climate, slopes. rock resistance, rainfall, temperatures, ARID regions.
Influenced by climate of region as well as the resistance of the rock
In hot and humid regions, slopes are gentle and rounded
High rainfall results in mass wasting and sheet erosion/ sheet wash
Key word: Sheet wash: Rainfall flowing over the land as a sheet
Higher temperatures encourage chemical weathering
This causes the soil layers to be thick and fine-grained
In ARID regions very little water is available, therefore very little chemical erosion occurs and THIN soil is found
Hills with narrow gullies and sharp ridges form in arid climates
Badlands are now evident
Slopes are steep and uneven
what are badlands?
They are rugged, have steep slopes have have very little farming value
What are Gullies?
small, narrow, long areas of erosion on a slope
How are basaltic plateaus formed?
They built up over millions of years by lava repeatedly pouring through long narrow cracks in the ground.
The lava floods the landscape, building up to form deposits hundreds to thousands of meters thick.
How do canyon landscapes develop?
refer to: erosion, running water, slopes
Develop where horizontal layers erode at different rates
Initially, the land is level, but running water soon finds weak places in the hard surface layer
Rivers erode vertically along cracks and joints and form deep, steep valleys
Valleys have steep sides
Explain what Karoo landscapes consist of
Develop out of canyon landscapes.
Landscape consists of flat-topped mountains or hills of differing widths, with steep , concave shaped sides.
The plateau is protected by a resistant hard rock, (dolerite)
Caprock ( hard, resistant rock) is evident on the top of features (usually sandstone and dolerite sills)
Rivers find weaknesses and erode vertically
What is dolerite?
Horizontal layer of igneous rock
Describe the formation of Karoo landscapes
Floor of canyon gradually becomes wider, plateau surface gets narrower
Plateau remains as its original height (due to resistant caprock)
The eroded plateau develops into a series of ridges and mesas or table mountains
Mesas are further eroded to form BUTTES, POINTED-BUTTES and eventually CONICAL HILLS
he valleys in a Karoo landscape WIDEN by means of ______
SCARP RETREAT or BACKWASTING
What is scarp retreat caused by?
lateral erosion and weathering
What does scarp retreat cause the formation of?
mesas, buttes, pointed buttes and conical hills
What is a pediplain and how is it formed?
It is a Large, low-angled plain.
As the plateau surface narrows, canyon floors become wider, and a pediplain is formed.
What are Mesas?
Flat-topped mountains with GREATER WIDTH than HEIGHT (Has caprock)
What are buttes?
Flat-topped hills with with GREATER HEIGHT than WIDTH (has caprock)
Define pointed-buttes
Narrow hills with a sharp peak at the top (has caprock)
What are conical hills?
Small pointed hills (NO caprock)
Define chemical weathering
Decomposition of rock due to chemical processes, often involving water, carbon dioxide and oxygen.
Define mechanical weathering
the physical break-up of rocks, often due to extreme temperatures
In humid climates, the slopes of hills are often suitable for FARMING and HUMAN SETTLEMENT.
Explain why the above statement is true.
Water causes the rock to decompose in a process called CHEMICAL WEATHERING resulting in thick, fine-grained soil layers forming gentle slopes
Farmers would use contour ploughing to grow crops
In arid climates, the rugged, steep slopes of the ‘BADLANDS’ have little agricultural value. Explain why.
There is little water
Mechanical weathering results in thin coarse-grained soil layers
An example of a basaltic plateau is the Drakensburg. state whether this area is suitable for human settlement and why.
Drakensburg is a great TOURIST ATTRACTION
Little value for human settlement and farming
High altitude results in cold temperatures
Slopes are also rugged and steep
It is nearly impossible to settle on canyon landscapes. explain why and give a reason for people still going there.
Impressive scenery = great tourist attraction
Farming is impossible due to rugged, steep slopes, no access to irrigation
Settlement is very difficult and virtually impossible to implement infrastructure (electricity and water provision) or construct traffic routes
