KOCHEL RITTER MILLER

What is Process Geomorphology? INTRODUCTION What is Process Geomorphology?

I. Overview Geomorphology (def): the study of landforms.

Descriptive → Quantitative I. Overview Geomorphology (def): the study of landforms. Descriptive → Quantitative

Descriptive → Quantitative I. Overview Geomorphology (def): the study of landforms. Descriptive → Quantitative “an interdisciplinary science” “the trade of geomorphology”

I. Overview B. Process Geomorphology:

I. Overview B. Process Geomorphology: 1. concept of process….

I. Overview B. Process Geomorphology: 1. concept of process….the action involved when a force induces a change (either chemical or physical) in the materials or forms at the earth’s surface.

I. Overview B. Process Geomorphology: 1. concept of process….the action involved when a force induces a change (either chemical or physical) in the materials or forms at the earth’s surface. 2. Loose definition: ”The study of landforms and the methods by which the landforms were(are) created”

II. The Basics of Process Geomorphology

II. The Basics of Process Geomorphology A delicate balance or equilibrium exists between landforms and process. 1. Geomorphic Systems

II. The Basics of Process Geomorphology A delicate balance or equilibrium exists between landforms and process. 1. Geomorphic Systems The balance between form and process is best demonstrated by considering both factors as systems or component of systems. A system is a collection of related components

II. The Basics of Process Geomorphology A delicate balance or equilibrium exists between landforms and process. 1. Equilibrium?????!!!!

1. Equilibrium?????!!!! Implies that landforms and processes exist in some type of unchanging condition (a balance of forces)

II. The Basics of Process Geomorphology A delicate balance or equilibrium exists between landforms and process. 1. G.K. Gilbert – “dynamic adjustment” Landforms reflect the interaction between the dominant process and the local geology

II. The Basics of Process Geomorphology A delicate balance or equilibrium exists between landforms and process. 2. William Morris Davis “cycles of erosion”

II. The Basics of Process Geomorphology A delicate balance or equilibrium exists between landforms and process. 3. John Hack “dynamic equilibrium”

II. The Basics of Process Geomorphology A delicate balance or equilibrium exists between landforms and process. 2. Defining Equilibrium and Time Scales Schumm (1977)

Valley Point Farm Ivy, VA

Fig. 1.3 high low Time (years) From Schumm (1977)

Fig. 1.3 high low Time (years) From Schumm (1977)

Fig. 1.3 high low From Schumm (1977)

II. The Basics of Process Geomorphology B. The perceived balance between process and form is created by the interaction of energy, force, and resistance.

II. The Basics of Process Geomorphology B. The perceived balance between process and form is created by the interaction of energy, force, and resistance. Process: (def) The action involved when a force induces a change in the materials or landforms at the Earth’s surface. OR

II. The Basics of Process Geomorphology B. The perceived balance between process and form is created by the interaction of energy, force, and resistance. Process: (def) The action involved when a force induces a change in the materials or landforms at the Earth’s surface. OR The method by which one thing may be produced from something else.

Process are either: Exogenic: action at or near earth’s surface (e.g., wind, water, ice, gravity) Endogenic: energy initiating the action is inside the earth

Force: Ingredients:

Force: Ingredients: Force F = m * a weight = mass * gravity A measure of force is weight (pounds, newtons)

Force: Ingredients: Force F = m a weight = mass * gravity A measure of force is weight (pounds, newtons) Force ~ energy, where energy is defined as the capacity to do work.

A measure of force is weight (pounds, newtons) Ingredients: *Force F = m a weight = mass * gravity A measure of force is weight (pounds, newtons) Force ~ energy, where energy is defined as the capacity to do work. Energy (or work) = force*distance = mass *gravity *ht F * d m * a *ht A measurement of energy is Joules

Modification of landforms results from the application of energy.

Modification of landforms results from the application of energy. Landforms represent the interaction between driving forces and resistance.   Driving Forces: Resistance Forces:

Modification of landforms results from the application of energy. Landforms represent the interaction between driving forces and resistance.   Driving Forces: Climate, Gravity, Forces generated inside the earth Resistance: Provided by the geologic framework The link between these two components here is PROCESS

II. The Basics of Process Geomorphology C. Changes in the balance between driving and resisting forces may destabilize the system. The system may cross a threshold, and may initiate a new pattern of equilibrium.

II. The Basics of Process Geomorphology C. Changes in the balance between driving and resisting forces may destabilize the system. The system may cross a threshold, and may initiate a new pattern of equilibrium. 1. Thresholds Changes in the geomorphic system when the limits of equilibrium are exceeded

II. The Basics of Process Geomorphology C. Changes in the balance between driving and resisting forces may destabilize the system. The system may cross a threshold, and may initiate a new pattern of equilibrium. 1. Thresholds Changes in the geomorphic system when the limits of equilibrium are exceeded

‘BEFORE’ ‘AFTER’

1. Thresholds Changes in the geomorphic system when the limits of equilibrium are exceeded a. Extrinsic Thresholds: caused by external controlling factors b. Intrinsic Threshold: usually caused by internal factors.

Geomorphic Thresholds: refers to the stability of a landform itself.

Geomorphic Thresholds: refers to the stability of a landform itself. “Has a threshold been crossed?”

II. The Basics of Process Geomorphology C. Changes in the balance between driving and resisting forces may destabilize the system. The system may cross a threshold, and may initiate a new pattern of equilibrium. 2. Complex Response (concept) a. " landforms behave differently spatially at the same time from a disturbance."

II. The Basics of Process Geomorphology D. Various processes are linked in such a way that the effect of one process may initiate the action of another. Process linkage: “Domino Effect”

II. The Basics of Process Geomorphology E. Geomorphic analysis can be made over a variety of time intervals. The interval of time chosen will have a bearing on conclusions made regarding the relationship between process and form

Time Framework: Which of the three time spans is most conducive to demonstrate the mechanics of process geomorphology? Consider a drainage basin: 1. Steady Time: see minor fluxuations in parameters. Likely not see permanent changes here. 2. Graded Time: steady-state measurements. Will vary with mean values of Qs and Qw. The flux of Q will determine the morphology. The responses of flux include channel incision/aggradation, pattern adjustment, modification in sinuosity 3. Cyclic time. Continued loss of sediment and energy suggest that the system continuously approaches, but never obtaining, and ultimate equilibrium condition. How we interprete geomorphology depends on which time scale is used. Usually, best if use steady or graded time