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Physical Geology QAB
Lecture GEOMORPHOLOGY
Jasmi Ab Talib
Geoscience amp Petroleum Engineering Department
TODAYS LECTURE amp OUTCOME
. Will concentrate on two main processes that modify the earth surfaces
Endogenic Processes Exogenic Processes
. Towards the end of lecture, you will be able to differentiate and recognise, in great detail
between endogenic and exogenic.
GEOMORPHOLOGY
Geomorphology from Greek , ge, quotearthquot , morf, quotformquot and , logos,
quotknowledgequot is the scientific study of landforms and the processes that shape them.
Geomorphologists seek to understand why landscapes look the way they do to understand
landform history and dynamics, and predict future changes through a combination of field
observation, physical experiment, and numerical modeling. Geomorphology is practiced
within geology, geodesy, geography, archaeology, and civil and environmental engineering.
Early studies in geomorphology are the foundation for pedology, one of two main branches of
soil science.
erosion and deposition which created them. weathering. interested in the origin and
evolution of landforms study of currently active processes amp past processes What shapes
the Earths surface .GEOMORPHOLOGY The science which studies the nature and history of
landforms and processes. Geomorphology what is it study of Earth surface processes and
landforms a historical science.
or the shifting of large. the breakdown of rocks and minerals at or near the surface of Earth
due to physical or chemical processes. glaciers. the movement of soil and rock due to forces
produced by water. as befits its status as one of the key areas of study in the earth sciences.
wind. the transfer of earth material. down slopes. and creep. fall. slide. and mass wasting or
mass movement. by processes that include flow. Also of interest are fluvial and eolian
processes those that result from water flow and wind. movable segments of lithosphere the
crust and upper layer of Earths mantle. Plate tectonics is discussed in detail within its own
essay and more briefly in other areas throughout this book. erosion. Included among these
processes are weathering. respectively as well as others related to glaciers and coastal
formations. Other processes also shape landforms. . and other influences.Shaping the Earth
Among the processes that drive the shaping of landforms is plate tectonics. gravity.
GEOMORPHOLOGICAL PROCESSES .
and tsunami . currents.Glaciers .Running water .Wind .Waves.Groundwater
.GEOMORPHOLOGY AGENTS Any natural medium capable of securing and transporting
earth material They remove materials from one part of the earths crust and transport and
deposited them elsewhere . tides.
GEOMORPHOLOGY AGENTS Running water Groundwater Wind Tsunami Waves Glaciers .
erosion. The mechanisms involved. and plate tectonics.Geomorphic Processes Geomorphic
processes are all those physical and chemical changes which effect a modification of the
earths surficial form The processes are dynamic processes at work in the earths landforms
and surfaces. Processes may conveniently be divided into those that originate within the
Earth endogenic processes and those that originate externally endogenic processes
exogenic processes exogenic processes. weathering. A B Endogenic Processes Exogenic
Processes . combine processes that are in some respects destructive and in others
constructive.
Geomorphic Processes Endogenic Processes Diastrophism Vulcanism Exogenic Processes
Gradation Degradation Weathering Mass wasting Erosion Aggradation Work of organisms.
including man Extraterrestrial Processes Infall of meteorites .
. the continual drifting of continental crust.Geomorphic Processes A Endogenic Processes
The rifting of the great lithospheric plates. and the expansion of oceanic crust from
midoceanic spreading centres all set deepseated dynamic forces into action. continents. and
mountains. Diastrophism is a general term for all crustal movements produced by endogenic
Earth forces that produce ocean basins. plateau.
Geomorphic Processes A Endogenic Processes The socalled geotectonic cycle relates these
larger structural features to gross crustal movements and to the kinds of rocks that form
various stages of their development. Examples of endogenic processes mountains and
oceanic basins building. . A folded mountain belts evidence for crustal deformation by Earths
internal forces.
Folded mountain belts . tends to be a localized process that distorts preexisting strata.
Epeirogeny affects large parts of the continents and oceans.Geomorphic Processes A
Endogenic Processes Orogenesis. or mountain building. primarily through upwards or
downward movements. and produces plateau and basins.
GEOLOGY OF SE ASIA after Tjia. .
Major Faults in Peninsula Malaysia ur Sesar Al r sa Se k Bo ir r Leb Sesa Sutura
BentongRaub Lebey Ses ar K uala Lum pur k Ba BATUAN METASEDIMEN KARBON rB sa
Se gi ing it T uk BATUAN SEDIMEN PERM BATUAN METASEDIMEN PERM Sesa r Mers
ing km .
Such plateau basalts are derived from fissure volcanoes. m thick and cover . sq km. like
volcanoes.Geological Processes A Endogenic Processes Geysers and hot springs.
Examples the Columbia plateau of the western United States is overlaid by volcanic basalts
that are more than . are often found in tectonically unstable areas. . Volcanoes are produced
by outpouring of lavas from deep within the Earth.
Geological Processes A Endogenic Processes Other kinds of volcanoes include shield
volcanoes. such as Mount Fuji or Mount St Helens. which are composed of interleaved
layers of different materials. . such as those forming the Hawaiian Islands. and strato
volcanoes. which are broad and convex in profile.
Sudden motion at the Earths surface is a manifestation of endogenic processes that can
wreak havoc through seismic sea waves tsunamis. so whenever an earthquake occurs. . P
waves always travel at higher velocities than S waves. The vibrations can range from barely
noticeable to catastrophically destructive. landslides. whereas secondary or transverse shear
waves S waves impart vibrations perpendicular to their direction of travel. P waves are the
first to arrive and be recorded at geophysical research stations throughout the world. The
waves are further differentiated by the kinds of motions they impart to rock particles.
Earthquakes can release energy thousands of times greater than the worlds first atomic
bomb. Earthquake. vibrations produced in the Earths crust when rocks in which elastic strain
has been building up suddenly rupture. surface collapse or subsidence sinkholes. and
related phenomena. or both. and then rebound.Geological Processes A Endogenic
Processes Earthquakes are caused by the abrupt release of slowly accumulated strain by
faulting or volcanic activity. they travel through the Earths interiorand the other four are
surface waves. Two are classified as body wavesthat is. Six kinds of shock waves are
generated in the process. Primary or compressional waves P waves send particles oscillating
back and forth in the same direction as the waves are travelling.
. . .. Jabatan Meterologi Malaysia..... . Based on observations since .. . . . estimated
.FREQUENCY OF OCCURRENCE OF EARTHQUAKES Descriptor Magnitude Average
Annually Great Major Strong Moderate Light Minor Very Minor gt .. estimated . estimated
Based on observations since .
EARTHQUAKE ACTIVITIES AROUND MALAYSIA .
Geological Processes A Endogenic Processes Impacts of earthquakes Tsunami .
local time P. miles under the ocean and miles from the coastline. local officials reported.M.
struck at A. Sunday GMT.M. The earthquake.SINGAPORE. measured at about . by the
United States Geological Survey in Hawaii. April A powerful undersea earthquake in the
South Pacific early today sent huge tides rolling across lowlying areas of the Solomon
Islands. The survey placed the epicenter . . inundating entire villages and causing an
unknown number of deaths.
Recent earthquake around our region .
also aids the process. Mechanical weathering contributes further to the breakdown of rock
by increasing the surface area exposed to chemical agents. looking out with the sky near the
top of the frame. Characteristic layering in the sandstone is visible.Exogenic Processes
Weathering Mechanical weathering is the breakdown of rock into particles without producing
changes in the chemical composition of the minerals in the rock. Ice is the most important
agent of mechanical weathering. Water percolates into cracks and fissures within the rock.
freezes. The force exerted by the expansion is sufficient to widen cracks and break off pieces
of rock. . Heating and cooling of the rock. Inside Lower Antelope Canyon. and the resulting
expansion and contraction. and expands.
Exogenic Processes .Geological Processes B.
of the Earths crust. Chemical weathering decomposes the rock mass to form new minerals
and substances. in which case it is referred to as biological weathering. breakdown of rocks
by physical and chemical processes at the surface. Exogenic Processes An inselberg
resulting from weathering of the outer part of the rock mass. which produces debris known as
regolith. Two main types of weathering can be identified. or in the top few metres. or the sea.
However. Physical or mechanical weathering breaks rocks into smaller fragments without
changing their chemical composition. ice. It is the initial stage in the denudation lowering of
the land surface of landscape. Weathering. This can subsequently be transported away by
such agents of erosion as running water. . the wind. both chemical and physical weathering
can also be brought about by the activity of plants and animals.Geological Processes B.
those formed at higher temperatures being more readily attacked than those which formed
at lower temperatures. Igneous rocks weathered into sandy clayey soils and gravels. and all
of the common igneous rock forming minerals with the exception of quartz which is very
resistant are changed in this way into clay minerals and chemicals in solution. which are the
main source of modern sediments . The minerals in igneous rocks may be unstable under
normal atmospheric conditions. Air and water are both involved in many complex chemical
reactions. Igneous rocks are commonly attacked by water. particularly acid or alkaline
solutions. In this process the minerals within the rock are changed into particles that can be
easily carried away.Weathering Chemical weathering is the breakdown of rock by chemical
reaction.
Rock forms at great temperatures and pressures C and MPa. such as when a batholith is
exposed at the surface. and acidic water attacks the feldspar minerals. and in granites there
are three mutually perpendicular sets of joints that develop when this overburden is removed.
experiences a drastic reduction in ambient heat and pressure. Two things cause this in
granites the quartz crystals expand about . because angular edges provide more than one
area of attack by exposing a greater amount of surface area. Thus the corners become
rounded. . turning them into clay. for granitic rock. Edges and especially corners of an
angular block weather faster than flatter surfaces.Spheroidal weathering Spheroidal
weathering is a type of chemical weathering that creates rounded boulders and helps to
create domed monoliths Spheroidal weathering occurs whenever a mass of rock most
typically granitic in composition.
Hydration Is the addition of water to a mineral and its absorption into the crystal lattice eg.
KAlSiO HO CO KAlSiAlOOH SiO KHCOOrthoclase illite solution . .ions of water and ions of
mineral. Carbonation Abundance of bicarbonate solutions cause the decomposition of
feldspars to clay minerals. H or OH. eg. CaCO HO CO CaHCO Calcium carbonate Calcium
bicarbonate . Hydrolysis Chemical reaction between a mineral and water.Chemical
weathering .HO Hematite Limonite . Solution Commonly first stage in Chemical weathering
amp removes the most readily soluble minerals. Iron oxides may absorb water and turn into
hydrated iron hydroxides FeO HO FeO.
Reduction of iron to ferrous. Reduction Opposite process of oxidation. Oxidation Process of
combining with oxygen. usually occurs in waterlogged anaerobic conditions in the absence of
free oxygen. it more soluble and mobile. eg. water is stained brown of oxides. . FeO O FeO
ferrous oxide ferric oxide . will increase in ve valence or decrease in ve valence.Chemical
weathering . Alteration of iron from the ferrous.
Ca. Na Aluminum hydroxide Hematite amp Limonite Quartz Solids that remain in soil Mg
Silica Ions that are carried away in water Chemical amp biochemical sediments Detrital
sediments .Products of weathering Primary Minerals Feldspar FeMg minerals Quartz Primary
Minerals Residual Minerals Dissolved Ions Clay minerals K.
.
WEATHERING PROCESSES .
WEATHERING PROFILE a A schematic vertical section through a weathering profile b In
reality. the weathering profile may be more complex. . resulting from structures in the rock
mass.
. The action of ice moving over a land surface is sometimes called scouring. plucking and
gouging are erosional processes restricted to glaciers. the companion process performed by
wind is known as deflation.Geological Processes B Exogenic Processes Hydraulic action is
the sweeping away of loose material by running water.