Flashcards in The Earth's Surface Environments Deck (15)
What are the major physiographic zones on the continents?
Cratons (shield and platforms)
Basins and rifts
Orogens (mountain belts)
What is the climate and how does it vary?
Climate - the mean condition of the atmosphere over a long period of time
- Takes into account temperature, humidity, atmospheric pressure, precipitation and wind
Climate variation - depends on latitude, altitude and (in continents) distance from the ocean
What are the earth surface processes?
What is weathering and what are the two types?
Disaggregation and alteration of rock to form weaker materials by reaction with air and water
Converts bedrock into soil and sediment
Makes rocks more prone to removal by erosion
2 types - physical and chemical
What is physical weathering?
Break up of rock masses into smaller particles with no alteration of it's mineral constituents
- frost shattering
- salt shattering
- thermal rock
- wet-dry cycles
- root wedging
Greatly increases surface area for chemical attack
What is chemical weathering?
Chemical reaction of mineral constituents with air and water to form new minerals and dissolved salts
Aided by biological action by plant roots and microbes
- iron and aluminium hydroxides
- residuum of resistant mineral particles (Quartz)
- salts of Ca, Na, K, Mg
What is erosion?
Physical removal of rock material from weathering site by
Erosion agent must overcome cohesion and weight of rock particles to lift and move them
What is meant by the term fluvial?
River systems draining precipitation from high ground to the ocean
Upward branching system of tributaries progressively converging with the trunk stream ending at delta or estuary
Erosion dominated and steeper channels near source
Deposition dominated and flatter gradients near mouth
Features of the deserts
Defined by very low precipitation
Describe the glacial environments
- Polar regions
- High mountains
- continental ice sheets
- ice caps
- floating ice
Permanent frozen water dominates
Snow accumulation exceeds melting
Ice is a dominant erosion and transport agent but melt water also a powerful agent
Describe coastal environments
Dominated by action of waves and tides
Waves are powerful erosive agents
Tides generate strong currents in coastal areas that move sediment
How are coastal systems shaped?
Wave and tide sediment transport
Describe the earths two major heat systems
Internal heat engine - drives plate tectonics and causes crust at plate margins to be thickened and mountain belts to rise (eg. subduction and collision zones)
External heat engine (solar energy) - drives the climate system which influences weathering, erosion and deposition on elevated ground
How does a rise of major mountain ranges cause climate to change?
Orographic rainfall (air forced to rise over them which cools and triggers precipitation)
Raised rock mass acts as heat sink for solar energy, causing general cooling of global climate
Enhanced chemical weathering in mountains removes more CO2 from atmosphere and hence decreases greenhouse effect and causes cooling