Geomorphology Flashcards
Geomorphology
The study of the origin of landforms based on cause and effect relationships
Form
Study of landforms, from which we can infer they evolutionary process
Process
The study of currently operating geomorphic processes from which we can infer their influence on the landforms
Inductive reasoning
Form —> process
Deductive reasoning
Process —> form
2 ways of geomorphology
By the approach taken to its study
Not done
Descriptive geomorphology
Observations and measurement of landforms
Dynamic geomorphology
Observation and measurement of currently operating earth surface process es
Historical geomorphology
Interpretation of relict landforms and deposits in order to understand past processes
Relict landforms
No longer dipositting
Reginal morphology
Study of landforms and process operating in a specific region of earth, often related to climatic regions of earth
Reginal morphology is also known as
Climatic geomorphology
Fluvial geomorphology
Rubbing water
Streams, rivers
Hill slope geomorphology
Gravity and water
Costal geomorphology
Agents: waved and currents
Glacial geomorphology
Agents: glacier ice
Pariglacial geomorphology
Agents: ground ice
Aoeolian geomorphology
Agents: wind
Extreme _______________ must pass for ________ processes to take place
Amounts of time
Geomorphic
(Neo) catastorphism
Geomorphic work taking place in short time
Rock weathering
The break down of rock, first step in denudation,
Provides material nessecary for debris cascade
What exactly is weathering
The breakdown or decay of rock on surface
Where a thing layer of regolith is created and stays in place
Regolith
Later if loose, broken and sometimes chemically altered rock on top of a bed of rock
Rock composition (2 points)
Rocks that cool more rapidly (extrusive) are more susceptible to weathering
Minerals which crytalise at high temps are more suacceptable to weathering
Rock structure (2 points)
Determines pathways of water and dissolved substances
Determines the surface that is exposed to weathering
Tors
Weather rock into spheres
Rock texture
Size of minerals and grains and crystals. Rock composed of smaller grains generally weather faster
Availability of heat (2 points)
Temperate fluctuates (expanding and contracting) weakens rock
High temps speed up chemical weathering
Availability of water and dissolved substances (4 ways)
When water freezes, it expands
Growth of salt crystals from salt water expands
Dissolved substances in water can enhance waters ability to break down
Water carried away the products of chemical weathering process
Slope orientation
Affects weathering by controlling a slopes exposure to sun, precipitation and wind
Vegetation (2 ways)
Organic acids from decaying vegetation promotes chemical weathering
Mechanical stress exerted by roots growing in cracks can force rocks apart
Subsurface water
The position of water on top of ground water in relation to the ground surface, and the movement of ground water play an important role
Two broad classes of weathering mechanisms
Mechanical weathering and chemical weathering
Mechanical weathering
Rock is broken apart by physical stresses being implied, no chemical alteration
4 types of mechanical weathering
Freeze thaw weathering
Salt weathering
Exfoliation
Biological weathering
Freeze thaw weathering
“Frost wedging”
Freezing and melting causes mechanical stress
9%
Joint block separation
Results of free style weathering, rock breaks into blocks
Salt weathering
Evaporation of salty water forms salt crystals which create mechanical stress as they grow
Exfoliation
Rocks slips off in sheets instead of breaking up
Biological weathering
Growth of tree roots in a crack. Expands rocks making other weathering occur inside
Chemical weathering
Rock breaks due to chemical alteration. No physical
Ions
From the rocks minerals are removed by water
Dissolved in water renter rock and combine with minerals
Exchanged between rock and water
4 types of chemical weathering
Hydration
Hydrolysis
Oxidation
Dissolution and carbonation
Hydration
Water is absorbed by rocks minerals to cause a change in the minerals structure and swelling
Results in spherical weathering
Hydrolysis
Breakdown of silicate minerals in rock by water and dissolved substances
Most common type
Oxidation
Oxygen reacts with certain metallic elements
Rusting of iron
Dissolution and carbonation
Weathering of rock by dissolving it’s mineral constituents by water
In easy terms: breakdown of rock by certain minerals dissolving
Carbonation
The dissolution specifically calcium, magnesium, potassium and sodium by water
Karst landscapes
when entire landscapes of limestone or dollmite are exposed to carbonation
Soil is composed of
50% minerals and organic matter
50% air and water
5 primary natural soil forming factors
Parent material
Climate
Organisms
Topography
Relief
Time
Soil profile
Vertical section of soil that goes form surface to deepest section
Pedon
Smallest unit of soil
Soil horizons
Different layers of soil
O, A, B, C
Humus
Mixture of decomposed and synthesized organic material
Eluviation
Removing fine particles and minerals by water
Soil fertility
Ability for soil to sustain plants
Loam
Common designation for the balenced mixture of sand, slit, and clay
Soil porosity
Available air spaces within a material
For a karst landscape to form:
Limestone must contain 80% calcium carbonate
Complex patterns of joints must be present
An air containing zone mist exist
Vegetation is needed
Sinkholes
Weathering by dissolution of limestone creates sinkholes
Karst valley
Indents in land
Fluvial geomorphology
The energy of rivers
The drainage basin
Also known as watershed
The drainage basin is the fundemental unit on earths surface that we employ to understand rivers and streams
Drainage basin
The area of earths surface inside which all water falling as precipitation eventually makes its way to a single river or stream
Discharge
Energy from rivers
Water balence equation
P=R+E+/-change in s
P=R+E+/-change in s
Precipitation = runoff + evaporation plus or minus the change in storage
______ varies at different time scales (either _____ or millienia)
Discharge
Minutes
Individual storms
The shape of storm hydrograph is influenced by basin size as well as basin shape
Annual
Means one year
The shape of annual hydrograph depends on climate
Freshet
Melting resulting in filling of streams
