Geomorphology - 2 Flashcards
Church
1996
Church, 1996
In geomorphology the 19th century ended in 1950
*post 1950 development of process response approach
Process response example
Barchan dune
What is the process in sand dune formation
Sand flux
What is the form in sand dune formation
Length, width, height, dune velocity
What is geomorphology scales concerned with
With phenomena spanning on vast Spatial and temporal scales
Geologic memory
Controls exerted upon relief, erodibility, erosivity and accommodation space (areas in landscapes where sediments are stored and reworked)
Climatic memory
Influence of past climatic conditions upon contemporary landscape forms and processes
Anthropogenic memory
Imprint of past human activities on contemporary landscapes
Whereby human disturbances in the past altered landscape forms, processes and associated flows/sediment fluxes in a manner that continues to affect the way the contemporary landscape works
Ahnert
1981
Ahnert, 1981
Geomorphological change and scale
-graph time and size, linear relationship
What was a turning point For geomorphology, 1950s paradigm
Triggered by the inability to understand time scales of observable processes with the spatial scale landscapes
10-3 year and 10-3 km
Normal human perception
E.g. scale of entrainment and transport of individual sand grains over a dune crest
Can not predict exactly how far or when but can give it a probability
10^-2years and 10^2
Life time
Cause and effect applied
Predict size and movement (form and process)
According to spacing, sediment supply and shape from wind flow
10^1 to 10^4 years and metres
Landscapes at a scale necessary to think about past climate change and exogenous constraints
Can’t understand landforms just by the operation of present day processes
Sand ramps
> 10^4 years and meters
Too few examples to follow normative rules
10^7 year and way below a metre
Below normal human perception
Models do not work
No physical or functional understanding
Time and space example
River
- understand river processes
- exists in a valley, knowledge of climate change
- exists in a landscape, use history of plate tectonics
Concepts of hierarchy and connectivity
E.g Drainage basin
Each level of drainage basin hierarchy includes the cumulative effects of lower levels of the hierarchy plus some new considerations, called emergent properties
1996
Church
Church,1996
Small timescale observation, result in predictions from models to understand long term processes
1985
Schummm
Schumer, 1985
Older and larger landforms are not independent and separate from small short-lives landforms
Hugget
2011
Hugget, 2011
As size and age of landforms increase, present conditions can explain fewer of its properties
Form = variables that interrelate in a system origin or function
Process = interconnected pathways it’s transport energy or matter
2009
Tucker
Tucker, 2009
Conceptual landscape models
Increase in modelling if systems CSDMs with computing and topographic data has helped revolutionise landform measurements change and dynamics
