GY2312 Geomorphological Processes GY2311 Geomorphological Processes and Landforms Dr Mark Powell/Prof Tony Parsons Room F44/F73 [email protected]/[email protected].

GY2312 Geomorphological Processes

GY2311 Geomorphological Processesand Landforms

Dr Mark Powell/Prof Tony ParsonsRoom F44/F73

[email protected]/[email protected]

DEPARTMENT OF GEOGRAPHY

Module introduction

What is geomorphology? Approaches to geomorphology

Historical approaches Davis’ ‘Geographical Cycle’ Alternative frameworks - King Climatic geomorphology

Functional (process response) approaches Aims of the module Learning outcomes

What is geomorphology?Geomorphology is scientific study of the origin of landforms.

Historical approaches

Denudation chronology

is the study of landform evolution based on sequential studies over time in which pieces of evidence are arranged in chronological order to obtain a series of reconstructions of the land surface at various stages of time.

Davis’ ‘Geographical Cycle’, 1899

Rival views – King (1935)

Davis’ – backwearing, peneplanation

King – downwearing, pediplanation

peneplanation (downwearing)

or

pediplanation (backwearing)?

Climatic geomorphology-morphogenetic regions

Functional approaches

Advantages of the functional approach

avoids the need to extrapolate from evidence to untestable inferences about landscape history;

provides opportunities for measurement and experiment leading to quantifiable relationships between landscape processes and forms;

permits greater specialisation

Disadvantages of the functional approach

difficulty of generating an understanding of long-term landscape evolution

Wooldridge (1958) on the origin of meanders

“Geomorphology is primarily concerned with the interpretation of forms, not the study of processes….. No esoteric research in fluid mechanics seem likely to add much to our comprehension of what is, in essence, a simple process in this, and like cases, of developing forms”.

Parker (1978) on the subject of alluvial rivers

“Alluvial rivers posses channels that are self-formed by the interaction of water and sediment. They thus represent a novel fluid flow problem in which one is asked to determine not only the flow in a given container, but also the geometry of the container itself”.

The question of scale

Which approach to adopt in tackling geomorphological questions is not so much a matter of choice, but is determined by the spatio-temporal scale of the investigation (Church, 1996).

Three scales……..

Landscape development:Small scale

Topic - The erosion of a particular soil particle

Question – Will a soil particle be entrained by overland flow and how far will it travel?

‘Best’ answer – There is a 30% chance that the particle will be entrained by the flow and, if it is, its travel distance will have a maximum probability of 15 cm, with a standard deviation of 4.3 cm.

Landscape development:Medium scale

Topic - The erosion of a hillslope

Question – How much material has moved off the hillslope and how far did it move?

‘Best’ answer – The landslide moved 2600 m3 of soil from the hillslope. The travel distance of the landslide was 200 m

Landscape development:Large scale

Topic – The evolution of the landscape

Question – How has this landscape developed?

‘Best’ answer – An account of the unique landscape’s history.

The approach of this course

Aims of the course

To demonstrate how an understanding of geomorphological processes provides a basis for understanding the origin and evolution of earth surface landforms and landscapes.

Particular emphasis is placed on understanding the mechanisms of mass movements of slope forming materials under the influence of gravity and the dynamics of sediment entrainment, transportation and deposition by water, wind and ice.

The structure of the course

GY2312 and semester 1 GY2311 - Processes

Forces, resistances and responses Hillslope materials and failures Fluid Flows Sediment transport

GY2311 Semester 2 – Landscape responses

Learning outcomes (1)

1) discuss how rock, soil, water, wind and ice respond to stress and how these responses determine their flow dynamics;

2) discuss the basic principles underlying the entrainment, transport and deposition of sediment by water, wind and ice;

3) apply a quantitative understanding of flow and sediment transport processes to solve geomorphological problems;

4) apply laboratory and field techniques to measure earth material properties and the flow of water;

5) produce a web-site to communicate information about field techniques relevant to the measurement of earth material properties.

Learning outcomes (2)

1) apply a knowledge of geomorphological processes to develop an understanding of landform and landscape development at a range of spatial and temporal scales;

2) discuss the concepts of process-response, magnitude, frequency and dominant events and their relevance for understanding landform development;

3) discuss limitations of the process-response approach to geomorphological study.

Wk 1 (Oct 3-7) IntroductionWk 2 (Oct 10-14) Forces, resistances and flows I

Forces, resistances and flows IIWk 3 (Oct 17-21) Hillslope materials and failures I

Hillslope materials and failures II Wk 4 (Oct 24-28) Fluid Flows I

Fluid Flows IIWk 5 (Oct 31 Nov 4) Field trip brief (Velocity profiles)

Field trip to River Sence (Velocity profiles)Wk 6 (Nov 7-11) Velocity profile clinic

Velocity profile clinicWk 7 (Nov 14-18) Directed reading 1 (no lecture)

Directed reading 1 (no lecture)Wk 8 (Nov 21-25) Directed reading 1 (no lecture)

Clinic session on directed readingWk 9 (Nov 28 Dec 2) Sediment transport 1

Sediment transport 2Wk 10 (Dec 5-9) Sediment transport 2

Sediment transport exerciseWk 11 (Dec 12-16) Non assessed test

Directed reading 2 (no lecture)Directed reading 2 (no lecture)

Assessment

GY2312 25% CW 75% ExamCW – Problem solving exercises

Hand in date Mon 16 Jan

GY2311 50% CW 50% ExamCW1 Problem solving exercises

Hand in date Mon 16th JanCW2 Exercise in landform

developmentHand in date Semester 2

The world “cannot be understood unless one first learns to comprehend the language and read the characters in which it is written. It is written in the language of mathematics….. Without which it is humanly impossible to understand a single word of it.” Galileo (1623).

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Reading

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Earth Surface Processes and Landforms

Journal of the British Geomorphological Research Group (www.bgrg.org)

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