GEOG319 Flashcards
What drives system change in process geomorphology?
Precipitation, temperature, and climate. With enough consistency, this creates environmental factors that drive system change (eg, low temps = high snow = glacial erosion).
What are the 3 types of Equilibrium?
Static
Steady-State
Dynamic
Static Equilibrium
Remain unchanged over time due to perfectly balanced forces, typically maintained by consistent environmental conditions. Time independent (days/months)
Steady-state Equilibrium
Inputs and outputs, long-term, = 0
Offers potential to model long-term responses to changes in input parameters.
Dynamic Equilibrium
Undergo continuous change, but the rates of change are relatively constant, resulting in overall stability or balance over time. Cyclic (millions of yrs)
Recovery Time
Time to return to natural state from perturbation
Reoccurrence Interval
Determines if steady-state is maintained
True or False, landform adjustment to perturbance is magnitude dependent.
True. The size of perturbation = the magnitude of the event. Thus, is magnitude dependent.
Driving Forces
Endogenic (inside Earth)
- Internal heat from radiation, drives tectonics.
Exogenic (from atmosphere, sun)
- Climate, solar radiation, gravity
Resisting Forces
- Lithology
- Friction, viscosity
- Trees, rock pins
- Friction, viscosity
Complexities
- Thresholds
Climate, rock weakness, system returns to new condition/equilibrium state if pushed too far.- Complex response
Response in other parts of the system, which are linked (like the butterfly effect).
Process linkage, can get multiple landforms from one perturbation.
- Complex response
What Can Be Conserved?
Heat, Momentum, Mass
Conservation of Heat (Thermal Diffusion) - 3 Types
Plutons, Ground Water, Atmosphere
Conservation of Heat (Thermal Diffusion) - Plutons
Heat increase through radioactive decay, heat loss to country-rock and crystallisation.
Conservation of Heat (Thermal Diffusion) - Groundwater
Heat gain from geothermal sources, heat loss to cooler rock, water, atmosphere.
Conservation of Heat (Thermal Diffusion) - Atmosphere
Heat gain from Earth and Sun, heat loss to space.
Conservation of Momentum (5)
Wind, Rivers, Ice, Mass Wasting, Flow (rate depends on viscosity).
Conservation of Mass (Elevation)
Change in elevation = uplift - denudation: dz/dt = U - E
U = thermal, tectonic, isostatic buoyancy
E = tectonic, chemical, physical
Basic Conservation Equation Structure
dx/dt = in - out
Geomorphic Transport Functions
Describe the physics of each part of the conservation statement.
Eg: How does ice flow, heat diffuse, rock turn to soil? –> into equation
Geomorphic Transport Function Example: Rivers
E ~ KA^(m)S^(n)
Erosion ~ K x A (upstream area)m x gradientn
Steady-state and GTF
inputs and outputs are equal, because our average value doesn’t change through time. This means dz/dt = 0, and we can make uplift assumptions.
Soil Conservation Equation
dH/dt = SPR - D
Moving Mobile Regolith
Change in thickness = gains - losses.
More soil into one part of slope, soil thickens through time and dR/dt is +
Less soil into one part of slope, soil thins through time and dR/dt is -