GEO 201: Introductory Geomorphology and Soil Geography (2 Units C: LH 30)

Learning Outcomes

This course introduces the students to key concepts and elements in geomorphology and soil

geography: At the end of the course, the students should be able to:

1. define the meaning, scope, and why different landforms exist;

2. identify and characterize various landforms in his community; and

3. explain their importance.

Course Contents

 The meaning and scope of geomorphology, rock types, their origins and characteristics.

 Nature and origin of second order relief forms of the continents.

 Structural landforms.

 The meaning and 275 scope of soil geography.

 Factors of soil formation.

 Zonal soils; azonal soils and intrazonal soils,

 Importance of landforms to human development.

The word “geomorphology” was first coined and used between the 1870s and 1880s to

describe the morphology of the surface of the Earth. But it was popularized by the American

geologists William Morris Davis who proposed the “geographical cycle” also known as “Davis

cycle”. Geomorphology is an important branch of Physical Geography (geomorphology,

climatology, biogeography, oceanography).

The word "geomorphology" comes from the Greek words geo (Earth), morph (shape/form),

and logos (study). Geomorphology is the scientific study of the formation, development, and

evolution of landforms and landscapes. Geomorphology is the scientific study of the origin and

development or evolution of topographic and bathymetric (study of underwater depth of lakes

and ocean floors) features caused by physical, chemical and biological processes that occur at

or near the surface of the earth. Geomorphology is the systematic and organised description

and analysis of various landforms of the earth. The word ‘landforms’ includes not merely micro

features of the land and but also major relief features such as continents, plain and plateaus

and a discussion of their origin and evolution is equally relevant. Geomorphology is dynamic

(constantly changing) in nature, that is changes caused by both external and internal forces.

According to Strahler, geomorphology is an analysis of the origin and evolution of earth

features. Geomorphology does not merely study the physical, chemical and biological processes

affecting the evolution of landforms but also the structure of the earth’s crust, the geological

processes as well as the climatic influences, because it is the combined influence of all these

factors that determines the landforms. According to W.D. Thornbury, geomorphology is the

science of landforms including the submarine topography. A.L. Bloom also defined
geomorphology as the systematic description and analysis of landscapes and the processes that

change them. According to German geologists Machatschek, Geomorphology is the study of

the physical processes fashioning the form of the solid surface of the earth as well as the

resultant landforms.

Geomorphology studies the evolution of landforms, it studies the physical, chemical, and

biological processes that shape the Earth's surface, including landforms, sediments, and the

structure of the Earth's crust. It is concerned with the scientific study of the origin and

evolution of the relief features of the earth. Geomorphology helps us understand how

landscapes look the way they do, how they've changed over time, and how they might change

in the future. It can also provide important information for environmental management, such

as landscape conservation and restoration. Geomorphologists use a variety of methods,

including field observations, physical experiments, and numerical modeling. Geomorphology

does not stand on its own, it relies on other disciplines of studies like physical geography,

geology, engineering, physics, Pleistocene (archaeology), geodesy and statistics for a proper

understanding of the field of study. It tries to explain the development of landforms and to

interpret their arrangement and distribution over the earth.

Developments of Geomorphology

Ofomata (2009), identifies six major stages through in the discipline has passed through. These

stages could be classified under the following headlines:

i. Catastrophism

ii. ii. Uniformitarianism

iii. iii. W. M Davis Cycle of Erosion

v. Process Study

vi. System Approach

Catastrophism

Man’s earliest attempt to interpret the landforms around him was speculative and based on

the theory of Catastrophism. This interpretation was informed by the occurrence of sudden

event, such as volcanism, earthquakes and floods, the nature of the manifestation of these

events left the lasting impression that every feature on the earth’s surface was a result of such

sudden occurrences. Consequently, it was believed that rivers flowed in valleys, simply because

the valley existed wherever there were found as a result of catastrophic rapture of the surface.

There was no question of imagining that rivers carried the valleys in which they flowed. The

catastrophic theory persisted up to the 18th and 19th centuries. There were some people who

tried to explain landforms otherwise. Some of their views resemble current thinking on such

matters, but they were certainly far in advance of their time and were largely ignored by their

contemporaries. A few of such cases are: Polybius (210-128BC), Aristotle (384-322BC), Strabo

(54BC-25AD), Seneca (BC-65BC), Leonardo da Vinci (1452-1519), Buffon (1707-1788), Targioni

(1712- 1784), The Frenchman, Guetthard (1715-1786), Another Frenchman, Desmarest (1725-

1815) and The Swiss, De Saussure (1740-1799). These men among others paved the way for the

next stage in the development of geomorphology.

ii. Uniformitarianism

The development of geomorphic thought was strongly controlled in Europe by the acceptance

of the idea of Uniformitarianism, first proposed at the turn of the 18th and 19th centuries by
James Hutton, elaborated by John Playfair in 1802 and stressed by Charles Lyell in his principles

of Geology, first published in 1830. It was based on Geikie’s maxim that “the present is the key

to the past”, that the processes acting at the present have acted throughout geological time

and that changes in landforms, although slow can be far-reaching. The idea recognized that

there is some order in nature, and that given enough time, whole landscapes can be created

and destroyed again by the operation of slow, yet relentless forces. Uniformitarianism was a

great advancement on the ideas of catastrophism. As long as it was held that the world was

created suddenly 4004 BC and that all phenomenon were due to catastrophic events, such as

Noah’s flood, progress was impossible on the other hand as King (1966) has pointed out,

Uniformitarianism can be taken too far, “it is easy to appreciate that the occasional extreme

flood accomplishes more change in a river valley than the intervening years of more flow”, this

escape from the ideas of extreme catastrophism, nevertheless, opened the way for the

development of modern ideas on the development of landforms. In North America, the period

1875-1900 has been referred to as ‘the heroic age in American geomorphology’ (Thornbury,

1969), because it was during this quarter of century that most of the major concept of

geomorphology evolved. To a large extent, these were the out-growths directly or indirectly, of

the work of a group of geologists who were connected with the series of geological survey of

the Western United States initiated after the American civil war. Three men may be mentioned

who did pioneer thinking in the field of geomorphology in America: Major J.W. Powell (1834-

1902) G.K. Gilbert (1843-1918) C.E. Dutton (1841-1912). Powell formulated the idea of the

base-level (1875), Gilbert introduced the concept of grade and attempted to arrive at a

quantitative study of factors such as river volume, velocity and gradient. Dutton introduced the
word ‘isostasy’ (1889) and made many useful contributions to geomorphology, particularly with

regards to the ability of the subaerial erosion to produce an intensive plane surface. These men,

along with others, collectively laid the foundation upon which W.M. Davis later built the

concept of a geological circle

catastrophism, nevertheless, opened the way for the development of modern ideas on the

development of landforms. In North America, the period 1875-1900 has been referred to as

‘the heroic age in American geomorphology’ (Thornbury, 1969), because it was during this

quarter of century that most of the major concept of geomorphology evolved. To a large

extent, these were the out-growths directly or indirectly, of the work of a group of geologists

who were connected with the series of geological survey of the Western United States initiated

after the American civil war. Three men may be mentioned who did pioneer thinking in the field

of geomorphology in America: Major J.W. Powell (1834-1902) G.K. Gilbert (1843-1918) C.E.

Dutton (1841-1912). Powell formulated the idea of the base-level (1875), Gilbert introduced the

concept of grade and attempted to arrive at a quantitative study of factors such as river

volume, velocity and gradient. Dutton introduced the word ‘isostasy’ (1889) and made many

useful contributions to geomorphology, particularly with regards to the ability of the subaerial

erosion to produce an intensive plane surface. These men, along with others, collectively laid

the foundation upon which W.M. Davis later built the concept of a geological circle

W. M Davis (1850-1934) Cycle of Erosion

W. M Davis clearly stands out as one of the most important names in geomorphology. He was a

giant among his contemporaries and influenced many of the succeeding generation of

geomorphologists. He is regarded to have done more than any other single man to found the
subject, although his views can no longer be held in their entirely. He greatly influenced the

development of the subject not only in his home land (America), but in Britain and elsewhere

during his many visits and by his writings. His contribution being to systematize the succession

forms in an ideal circle and to provide terminology. Davis took Uniformitarianism as a basis in

sketching the development of landforms. He formulated a geomorphic principle of fluvial

denudation, known as the erosion cycle or the cycle of erosion (1899). It is based on an

idealized conception that a river has a life history and like human beings, passes through the

stages of youth, maturity and senility (old age) in its developments, each stage having definite

characteristics with which it is associated and which distinguish it from other stages. It is

assumed, that the stage on which the cycle is developed is a new land surface created uplift and

dislocation of a portion of the earth’s crust. The uplift is rapid and is followed by a long period

of still stand when no further uplift occurs to interrupt sequential changes in the landscape.

Also the newly uplifted surface was formerly under ocean level and has thus become exposed

for the first time. In consequence, the landscape is assumed to be composed of initial

landforms. Davis regarded his outline as the cycle of normal erosion, in which running water is

the main agent of landform development and consider other form of development as climatic

accidents. In spite of the limitations, the Davisian formulation dominated geomorphological

thinking for a long period of time, and some of the shortcomings of his scheme led logically to

the next stage in the development of the discipline.

Climatic Geomorphology

Davison geomorphology was founded on the idea of normal erosion as developed in humid

temperate areas of the world, and in which running water is the main agent of landform
evolution. Processes related to other agents were considered as climatic accidents in the

normal setup of things. Such an outline neglected important relationships that exist between

climatic conditions and the operation of geomorphic processes. Doubts were soon expressed

on the validity of normal erosion in geomorphology, as evidence increased on the part of

climatic influence on landform development. Even Cotton (1942), a strong supporter of the

Davison viewpoint, suggested that perhaps there are sufficient differences in the relative

importance of deflation and lateral erosion by streams in arid, semi-arid and savanna regions to

justify recognizing each as a distinct geomorphic region.

It was realized that what exists is not normal erosion unsystematically disrupted by climatic

accidents, but climatic geomorphology, ‘in which distinctive arrays of geomorphic processes

and resulting landforms are referred to specific controlling climates’ (Dury, 1969). The idea of

climatic geomorphology was first chiefly developed on the European mainland and was

formally introduced into American by L.C. Peltier (1950) who summarized the process of

morphogenetic regions. Landform development is thereby made dependent on climate and

through climate process, which arises from one climatic region to the other.

Process Study

Contemporary effort in geomorphology centers on study of process of landform development.

This study is not merely descriptive but essentially quantitative, following accurate

measurement of the rates at which the process operates. The application of quantitative

techniques, aided by the use of computer, facilitates the handling of the numerous variables

that underline the operation of geomorphic processes. These process studies make geomorphic
statement more objective and scientific and also enhance the ability of geomorphologists to

predict the outcome of the operation of processes in landform development.

System Approach

Alongside process studies is the introduction of the system approach in landform studies. The

use of system theory as an overall explanatory structure within geomorphology marks a

significant change in the subject. Accordingly, there has been a move away from the pre-

occupation with change and development towards the view that landforms may be balanced

systems, with process and form closely interrelated, yet with the system actively aimed at

maintaining a stable form rather than producing progressive change (Anderson and Burt, 1981).

The use of system approach as the organizing paradigm in geomorphology has accompanied

the general development of model building with the 18 subject. Studdart (1967) advanced four

reasons why the system approach is such a useful and fundamental organization concept:

i. First, systems are monistic, bringing together relevant component of the physical and

human environment.

ii. Secondly, systems are structured in an orderly and rational way so that the form of the

system can be easily investigated.

iii. Thirdly, systems are functional entities incorporating the throughput of matter and

energy, so that the system is not just a frame work but dynamic operational unit and;

iv. Finally, the majority of physical systems are governed by negative feedback

mechanisms which limit change and maintain system stability.

This is an attempt at outlining the extent to which geomorphology covers as a field of study. It

studies different landforms and the processes involved in producing the different landforms. It

tries to understand the difference in appearance of the numerous landforms, the history of the

landforms and predicting changes that are likely to happen in the landforms through

observations, physical experiments and numerical modeling.

Geomorphology also form part of physical geography, engineering, physics, geology (science of

understanding the shape, form and measurement of the physical characteristics of the earth),

archaeology, geodesy etc. These science overlap so that trying to differentiate their scope is not

desirable or practicable. It studies landforms produced by the processes of erosion, different

types of landforms and their formative agents. The findings of results in geomorphology have

been applied or used in solving environmental problems.

The earth’s crust consists of rocks. A rock is a naturally occurring solid mass or aggregate

of minerals. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except

for the liquid outer core and pockets of magma (molten material). The types and abundance of

minerals in a rock are determined by the manner in which it was formed. Rocks are composed

primarily of grains of minerals, which are crystalline solids formed from atoms chemically

bonded into an orderly structure. Some rocks also contain mineraloids, which are rigid,

mineral-like substances, such as volcanic glass that lack crystalline structure. Most rocks

contain silicate minerals, compounds that include silica tetrahedra in their crystal lattice, and

account for about one-third of all known mineral species and about 95% of the earth's

crust. The proportion of silica in rocks and minerals is a major factor in determining their names

and properties.

Rocks are categorized by the minerals included, its chemical composition, and its formation.

Rocks are classified according to characteristics such as mineral and chemical

composition, permeability, texture of the constituent particles, and particle size. These physical

properties are the result of the processes that formed the rocks. Over the course of time, rocks
can be transformed from one type into another, as described by a geological model called

the rock cycle. This transformation produces three general classes of rocks: igneous,

sedimentary and metamorphic. The three classes of rocks are sub-divided into many groups.

There are, however, no hard-and-fast boundaries between allied rocks. By increase or decrease

in the proportions of their minerals, they pass through gradations from one to the other; the

distinctive structures of one kind of rock may thus be traced, gradually merging into those of

another. Hence the definitions adopted in rock names simply correspond to selected points in a

continuously graduated series.