Gr.11 Geomorphology π Flashcards
What is topography?
The shape or relief of the land
What does the structure of rocks determine ?
The type of landforms and therefore the landscape of an area
What are horizontal rock layers called?
Strata/ stratified rock
What are bedding planes?
The planes separating horizontal rock layers.
What is the difference between exogenic forces and endogenic forces?
Exogenic forces: originate at the earthβs surface and decrease relief by, e.g. weathering and erosion.
Endogenic forces: originate within the earthβs surface and increase the relief, e.g. uplift
What does it mean if rock is uniformly resistant to erosion?
Rocks erode at the same rate.
What are 4 horizontally layered rock formations?
Hilly landscapes
Basaltic plateaus
Canyons
Karoo landscape
Which is more resistant: dolerite or basalt?
Why?
Dolerite. It cools slowly underground. Basalt cools faster on the earthβs surface
What are the 2 types of hilly landscapes that may form?
Series of rounded slopes
Hills with narrow gullies and sharp ridges (called badlands)
What causes rounded slopes? Give an example
Humid climates: sheet wash occurs and removes the surface material.
Eg. Valley of 1000 Hills, KwaZulu-Natal
What is sheet wash?
Gushing run-off
What causes badlands? Give an example
Arid regions: sheet wash washes over slopes with little/ no vegetation. Erosion takes place quickly.
E.g. Death Valley, California
What is a basaltic plateau?
A lava plateau with steep cliffs.
Give an example of a basaltic plateau
The Drakensberg
What causes a basaltic plateau to form?
Upward movement of the earthβs crust
Or fissures forming and magma welling up to surface over a long time
How do basaltic plateaus erode?
Vertical joints and cracks in the basalt erode to from deep cliffs
Why does a plateau have a flat top?
Lava pours onto the surface of the earth. This forms a hard cap rock which is uniformly resistant to erosion.
What is another name for a canyon?
A gorge
How does erosion take place in a canyon landscape?
Water finds weak places in layers and erodes vertically. The more resistant the layers, the steeper the slopes.
How do canyon landscapes differ in different climates?
Dry regions: steep, rugged, cliff-like slopes
Wet regions: hilly with more vegetation
Give an example of a canyon landscape
Fish River Canyon, Blyde River Canyon, Grand Canyon
Decide into resistant and less resistant to erosion:
Sandstone, shale, clay, granite, limestone, quartzite
Resistant: sandstone, granite, quartzite
Less resistant: shale, clay, limestone
Out of what do Karoo landscapes develop?
Canyon landscapes
Describe the rock in a Karoo landscape
Resistant hard layer (sill) such as dolerite on top of layers of sandstone and softer shale. Flat topped hills and wide, flat plains