Lecture 12 - Landscape Change

Question 1

What is the Definition of Geomorphology?

Answer 1

-The geoscience that studies how and why the landscapes change
-Geo (Greek) = Earth, logos = study, morpho = shape
-Geomorphologists describe and quantify the shape/ surface of Earth to investigate processes responsible for changes

Question 2

What is Conceptual Modelling?

Answer 2

-Representation (usually diagrammatic) of the Earth surface system, depicting key processes, their interaction and resulting changes in the landscape

Question 3

What is Physical Modelling?

Answer 3

-Laboratory technique that stimulates geomorphological processes as they happen in nature (e.g. a meandering river)

Question 4

What is Numerical Modelling?

Answer 4

-A methodology to study landscape changes, mainly on a temporal scale (millenia to millions of years)
-They are based on equations that describe geomorphic processes
-They are particularly useful to investigate connections among controlling factors (e.g. relationships between fluvial incision and slope processes)

Question 5

What is the First Guiding Principal of Landscape Change?

Answer 5

-Mass conservation = mass cannot be created nor destroyed, only transformed and transported from one place to another
-Example: material eroded from mountains (source, transported through the transition zone, partly deposited in the floodplain, and the rest deposited in the sea (sink)

Question 6

What is the Second Guiding Principal of Landscape Change?

Answer 6

-Threshold = a limit above which processes may or may not happen, or happen at different rates
-Events occur when a threshold has been overcome
-They depend on the spatial scale (some thresholds may be the different in some areas for the same event)
-Example: A landslide occurs when a threshold (water ingress within the rock) is overcome

Question 7

What is the Third Guiding Principal of Landscape Change?

Answer 7

-Time of landscape evolution
-When perturbed (altered) by climatic and tectonic changes, landscapes resonate with a range of frequencies
-Different landscapes respond differently to alterations, so rates of geomorphic processes must be calculated for each individual landscape and used as parameters to validate models of future predictions

Question 8

What are the Main Agents of Landscape Change?

Answer 8

-Gravity
-Wind
-Water
-Transport rules = flux is proportional to slope (gradient)

Question 9

Describe how Solar Energy contributes to Global Surface Temperatures

Answer 9

-Energy from the sun to Earth is spatially and temporally variable due to:
-Fusion activity in the sun is on
an 11-year cycle
-The ellipticity of Earth’s orbit
around the sun
-Tilt of the Earth axis which
produces the seasons
-The flux of energy is roughly: 1370W/m2 (1 watt = 1J/s)

Question 10

Describe how Greenhouse Gasses contribute to Global Surface Temperatures

Answer 10

-Earth loses heat from its interior at a rate of around 40TW
-This flux would produce an average surface temperature of -18C
-Average temperature of Earth is 15C due to presence of atmosphere and greenhouse gasses; this creates the right temperature and pressure for the water to be liquid and allow life to flourish

Question 11

What is a P-T Diagram?

Answer 11

-P and T = pressure and temperature
-Otherwise known as phase diagrams; they show the phase (solid, liquid, vapour) of a substance with changing environmental conditions (ie. pressure and temperature)