shaping earth's crust Flashcards
Weathering
Breakdown and decay of rocks that are exposed to weather
Two main types of weathering
Mechanical
Chemical
Mechanical weathering example
Freeze thaw action/frost action
- Water runs into joint/crack in rock
- Water freezes, expands, putting pressure on rock
- After freezing + thawing, rock fragments break off
Chemical weathering example - rainwater on limestone
- Rainwater travels through atmosphere
- Mixes with carbon dioxide
- Makes weak carbonic acid
- Falls on limestone
- Changes calcium carbonate (in limestone) to calcium bi carbonate
- Process/reaction is carbonation
- Makes it easier for rainwater to dissolve limestone
The burren
Carbonation causes rock to dissolve.
Little material is left ons surface to form soil, appears as bare rock
Landscape looks v barren, known as limestone pavement
Surface covered in lots of cracks. Water has laid in these cracks for long.
Grykes
The cracks in the rocks
Clints
The slabs of rocks
Swallow hole
Sometimes grykes may get bigger and a swallow hole will be formed.
Lets water flow underground,
Cave
As water flows beneath surface, it dissolves limestone and cuts out tunnels called caves
Cavern
If cave is enlarged, its called a cavern
Stalactite
Water containing calcium carbonate drips from ceiling.
Evaporation takes place leaving deposits of calcite
Deposits build up over time to form stalactites
Stalagmite
Water containing calcium carbonate drips from ceiling to floor
Evaporation takes place leaving deposits of calcite on floor
Deposits build up over time to form stalagmites
Pillar/column
Formed when stalactite and stalagmite join together
or when stalactite reaches ground or stalagmite reaches ceiling
Flora
Burn has varied plant life and many rare plants can be found such as orchids, ferns, avens
Fauna
Burren’s wildlife includes green moth, butterlies, wild goats
Landscape
Burren ha wide range of scenery for tourists. Attraction include Aliwee caves and Cliffs of Moher
History
Burren’s monuments and archaeological sites provide evidence of historical settlements. These include dolmens and ring forts
Mass movement
Movement of any loose material down slope under influence of gravith.
Loose material incl. loose rock, mud, soil (regolith)
Influences of mass movement
Gradient
Water content
Human acitivity
Vegetation
Gradient
Fastest when slope is steep
Water content
Water acts as lubricant, making regolith heavier + surface slippery
Human acitivty
Cutting into hillside during construction of roads + railways creat steeper slope
Vegetation
Roots of trees + plants bind soil together, slowing down rate of mass movement
Types of mass movement
Classified by speed
slow:
Soil creep
fast:
landslide
bog burst
avalanche
soil creep
occur on very gentle slopes
might not be noticed except for effect on surface objects eg. leaning poles, fences, walls
greatest near surface, decreases with depth
landslides
Sudden rapid movement of regolith down slope
most common in mountainous areas
may occur along coastal cliffs which have been undermined by sea erosion
causes of landslides
road/railway cutting into steep slope
constant erosion by waves causing undercutting of cliffs
earthquakes and their aftershocks can trigger landslides
Bog burst
movement of peat down hillside
caused by heavy rain saturating peat
can be caused by human activity such as excavation
mudflows
can occur on both gentle + steep slopes
torrential rainfall saturated soil and turns into mud
can occur after volcanic eruption
lahar is a volcanic landslide, mud mixes with lava + ash
Denudation
Wearing down of solid + loose materials of Earth’s crust
Occurs by weathering + erosion