DIASTROPHISM/EARTH’S MOVEMENTS – ADVANCED PHYSICAL GEOGRAPHY
Diastrophism (Distrophic forces) refers to all processes that move, elevate or build up portion of the earth’s crust through orogenic processes. Example, the mountain building and epirogenic forces involving uplifting or submergence of large part of the earth’s crust. The effects of Earth’s movement can be categorized into two groups such as Faulting and Folding.
FAULTING
Faulting is the process which involves the fracturing of the crust to form fault. OR
Faulting is the process of rocks displacement either horizontal or vertical along the fault plane. OR
Faulting is the fracturing and breaking of the rocks within the earth’s crust which result into movement of the rocks.
The faulting process caused by both forces i.e tensional force, shear force, and compressional force.
TYPES OF FAULTS
There are various types of faults but the common are;
i. Normal fault:
These are fault produced by tensional forces. They lead to both down throw and up throw movement of the fault block. The fault can be either vertical or inclined.
ii. Reverse fault (Thrust fault):
It is forms due to compressional forces on the crust. It is associated with upward movement of the hanging wall block along the fault in relation to the foot wall block.
iii. Overthrust (Nappe) fault:
This fault is also called as strike, shear, slip, wrench, or transcurrent fault.
Is the vertical fracture produced when two rock blocks slide against one another.
iv. Transform (Tear) fault:
Is the fault within the over thrust fold along which one limb slides over the other limb due to compressional forces.
v. Monocline fault:
It’s a tensional fracture in which the strata are bent or flexed. It is closely related to the normal fault but the normal fault has horizontal strata.
vi. Trap-door fault:
These caused by compressional forces acting on crustal rocks. The rocks are forced to upward resulting to the formation of an anticline.
CAUSES OF FAULTING
1. Faulting caused by tensional forces which stretch the rocks of the earth’s crust to different directions causing the rocks to fracture.
2. Faulting caused by compressional forces which push the crustal rocks together resulting to faulting.
3. Faulting caused by shear forces this involves two parallel forces moving in the opposite direction. They result is creation of lines of weakness, hence fracturing of the rocks.
LANDFORMS ASSOCIATED WITH FAULTING (EFFECTS OF FAULTING ON LANDSCAPE)
The effects of faulting on landscape can categorised into direct effects and indirect effects.These are;
1. Direct effects of faulting on the landscape;
i. Formation of step faulting:
Is the process which leads to the formation of several parallel faults. Therefore, the faults appear as a series of steps on either one side of the rift valley or both sides.
ii.. Formation of rift valley (Graben):
Is a flat floored v-shaped valley depression which is bordering on either side by fault scarps. It is formed by either tensional forces or compressional forces, where by the line of weakness occurs as a result to the formation of normal fault due to tensional forces and reverse faults for compressional forces, hence these forces pull the rocks apart resulting the central block to sinking down relative to the surrounding block therefore the rift valley were formed.
Example the Great East Africa rift valley was formed by both force tensional forces for eastern arm and compressional forces for western arm. Other example Rhine rift valley in Central Europe, the Clwyd Valles in North Wales, the Central valley and Great Glen valley in Scotland, Benue rift valley in West Africa, Baikal rift valley in Siberia.
iii. Formation of Block Mountain (Horst or Fault block):
Is the flat top upland formed under the influence of either tensional forces or compressional forces. During the formation, the central block raised up relative to the surrounding block. Hence the raised block form upland known as Block Mountain.
Example; Ruwenzori mountain in Uganda, Black forest mountain in German, Mts Pare and Usambara in Tanzania, Vosges in France, etc.
iv. Formation of fault scarp / Escarpment / Cuesta:
Are the dip slope and scarp slope. It’s a steep, cliff like slope or face of a fault. It is formed along fault line where rocks have been displaced both normal and reverse fault as a result to the formation of scarps.
Example; Chunya and Manyara area in Tanzania, Mau, Nyandarua and Nyando in Kenya, and Butiaba scarp in Uganda.
v. Formation of tilted block / Fault block:
These are series of raised and tilted block on landscape with angular ridges and depressions. It is formed due to greater compressional forces on one side of the middle block as a result of raised higher than the other hence the tilt block are formed.
Example; Western part of U.S.A (Great Basin), Afar triangle in Ethiopia, etc.
vi. Formation of fault valley:
This is valley opened by a single fault under the influence of tensional forces or compressional forces. Example; Eden valley in England.
2. Indirect effects of faulting on the landscape;
i. Formation of water falls:
When the vertical fault across a river valley may cause to the formation of the water fall. Example Rolambo waterfall in Zambia.
ii. Formation of Offset River (offset drainage):
If the tear fault across a river valley may cause the river to take offset at the point where it crosses the fault line. In this case the river follows the line of fault until it region the former course.
iii. Formation of Rift Valley Lake:
When the flat floored depression of rift valley become site of lake due to river drained into it hence forming inland drainage. Therefore, when the rift valley hollow occupied by water called rift valley lake. Example Lake Tanganyika in Tanzania.
iv. Formation of river flow:
The river may follow straight natural fault valley especially in areas of tilt-block faulting and where differential movements have raised some parts while lowering others.
v. Formation of springs:
Due to faulting, the springs can be formed because the fault lines provide line of weakness through which underground water can come out naturally from underground water table.
vi. Formation of reversed river (reversed drainage):
Sometime faulting and uplifting a crossing a river valley with gradually force the river to reverse its direction and dissects backward its unable to maintain the original direction flow. Example Malagarasi river in Tanzania.
vii. Formation of fault guided valley:
This is a fault which cause rock to be shattered and crushed to the extent that rocks are more easily eroded than those further from fault. Example Santa river in Guinea.
THE SIGNIFICANCE OF FAULTING TO HUMAN ACTIVITIES
i. Source of H.E.P generation; Because faulting leads to the formation of water falls which can be exploited for the production of H.E.P which can be used in industries, at homes, etc.
ii. Source of tourist attraction; Due to their features like rift valley, horst mountain, etc. which earns a country foreign exchange.
iii. Source of mineral exploited for industrial development; Because along the faults are found minerals deposits eg. copper in Uganda, trona, fluorspar and diamond in Kenya.
iv. The rift valley lakes provide water for domestic, irrigation and industrial use eg. L. Magadi, L. Tanganyika, etc.
v. Sometimes springs may be formed at the base of escarpment may attract settlement.
vi. Source of exploitation of fuel for industries. Due to deep fissures toward the petroleum site underground.
vii. Escarpment and block mountains may form barrier which may provide difficult during the construction of roads and railway.
viii. It leads to modify the climate of the area resulted from highlands such as block mountain.
ix.Sometime cause formation of earthquakes due to frequent faulting process.
x. Small rift valleys from lowlands may be suitable for settlements and agriculture eg. Rhine rift valley in Western Europe (German).
FOLDING
Folding is the process of wrinkling or crumping of the earth’s crust. OR
Folding is the process of wrinkling or bending or crumpling of the earth’s crust producing upfolds and downfolds.
It is a result from compressional forces which cause wide spread wrinkling.
TERMINOLOGY ASSOCIATED WITH FOLDING
i. Axis: This is the central line between the limbs of the fold.
ii. Limb: The side of the fold. If the axis dips in the direction of the fold is said to pitch in the direction of the dip.
iii. Thrust plane: The line of fracture along which the mass of rock is usually thrust bodily.
iv. Isoclinal folding: This is a series of parallel folds produced by compressional forces. It is either inclined or vertical.
v. Syncline: Is the down fold.
vi. Anticline: Is the up fold.
TYPES OF FOLDS
There are several types of folds. These are;
i. Simple or symmetrical fold:
This type of fold formed when the intensity of compressional forces is similar from each direction i.e the limbs are the same in nature.
ii. Asymmetrical fold:
This form occurs where one side of the fold is steeper than the other. Compressional forces is stronger from one side to push one limb further upwards.
iii. Overfold:
This type of fold occurs where compressional forces are intense to push the steeper limb on one asymmetrical fold upwards.
iv. Recumbent fold:
It is a type of asymmetrical fold which forms when forces intensify from one side. This pushes the steeper limb to lie above the other limb.
v. Over-thrust (Napper) fold:
It is a type of fold which forms when the pressure continues to fractures the rocks. It makes the upper limb of the fold to move upward along the line of fracture.
vi. Anticlinorium and Synclinorium fold:
Anticlinorium is a large anticline with minor anticlines and synclines superimposed on it.
Synclinorium is a large syncline with minor anticlines and synclines on it. Example of anticlinorium folds appears in the Southern upland of Scotland.
vii. Pericline (centroline) fold:
This is a form of an anticline usually of small dimension in which the limbs have been forced to pitch vertically along the axis. It is in sense an elongated dome.
viii. Geosyncline fold
It is a very wide syncline (down fold) produced a result of the subsidence of the earth’s crust. Example Mediterranean Sea.
EFFECTS OF FOLDING ON LANDSCAPE (LANDFORMS OF FOLDING)
The following landforms resulted from folding process. These are;
i. Formation of Fold Mountains
It is the huge mountain ranges formed as a result of folding process where the compressional forces are intense as a result of very lofty up folds. Most of Fold Mountains occurs at adjacent to the coastal areas. It is categorised into young fold mountains and old fold mountains.
Example of fold mountains are Atlas in North Africa, Rocky in N/America, Appalachians in Eastern N/America, Andes in S/America, Ural in Eurasia (separate between Europe and Asia), Alps in Europe (Switzerland), Cape ranges in S/Africa, etc.
ii. Formation of geosyncline
This is very extensive depression formed by folding along the coast where by tremendous compressional forces has lead to displacement of a very wide syncline.
Example; Mediterranean Sea between Africa and Europe.
iii. Formation of synclinal valley:
These are narrow-deep down fold. They are associated to fold mountains. Therefore, can be traced in the examples of Fold Mountains cited.
iv. Formation of synclinal basin:
Refers to the broad shallow down-fold. It may result due to simple folding which covers a wide area. Example; Landon basin, Paris basin, Upper Rhine basin, etc.
SIGNIFICANCE OF FOLDING TO HUMAN ACTIVITIES
i. Fold mountains attract tourism.
ii. It provides routeways for transport if mountains passing with the syncline.
iii. Fold mountains sometimes forms protective barriers in times of war.
iv. Fold mountains attract dense settlements and agricultural activities due to heavy rainfall received.
v. Source of timbers for building and construction, this associated with heavy rainfall on fold mountain slopes.
vi. It provides suitable sites for generation of H.E.P due to presence of steep gradient and deep valleys on fold mountain.
vii. It enables the people to carry out some outdoor activities due to descending winds create dry conditions which discourage human activities such as crop farming.
viii. Source of valuable minerals eg. copper, gold, lead, silver, etc.
ix. The steep and rugged relief on high fold mountains discourage construction of road and other routes of transport, hence act as a barrier to transport and communication.
x. It provides good sites for afforestation due to deep fertile soil on synclines.
FOLD MOUNTAIN
Fold mountain is the mountain formed due to wrinkling of the earth’s crust. They occur where rocks lay in layers. Fold mountains result from lateral forces of compressional. During the process layers of rocks bend up and form fold mountains and those which bend down form valleys or become sites of seas.
TYPES OF FOLD MOUNTAINS
The fold mountains can be categorised into two major types. These are;
1. Young fold mountains:
Are the fold mountains that the recent origin and majority of them were formed by movements that took place during the mid-Cenozoic era and good examples are the Himalaya, Alps, Atlas, and Andes mountains.
2. Old fold mountains:
These mountains were formed long time ago and good example is Cape ranges in South Africa.
NATURE / CHARACTERISTICS OF FOLD MOUNTAIN
1. They are chains of mountains which are very extensive covering thousands of kilometers on the mountains. Thus, fold mountains form the most extensive ranges in the world. They were formed in different geological time so there is old fold mountains eg. Appalachians and cap ranges, the young fold mountains are recently formed eg. Himalaya, Alps, Rockies, etc.
2. Various degrees of fold mountains depend on the intensity of compressional forces. The young fold mountains have the highest peaks on the earth’s surface eg. Mt. Everest in Himalayas and Aconcagua in Andes.
3. They show great thickness of sedimentary rocks due to the fact that initially before folding either up or down, the rocks were laid in layers and in different geological times they kept on being deposited in same areas until they were very thick and start to fold.
4. They normally occur on the boundaries of tectonic plates. This happens two continental crust collide and is neither can sink, are forced up into fold mountains eg. Indian plate with Eurasian plate forming Himalaya, and African plate with Eurasian plate forming Alps.
5. They are interrupted by volcanic intrusion eg. batholiths. These volcanoes are likely to form either a long chain of fold mountains eg. Andes or, if the eruptions takes place offshore, an Island are is formed eg. Japan and West Indies.
WORLD DISTRIBUTION OF FOLD MOUNTAIN
Fold Mountains are not uniformly distributed in the continents. They are distributed along the margins of continents where plates collided. The young fold mountains form their own belts and the old fold mountains form their own belts as well.
I: DISTRIBUTION OF YOUNG FOLD MOUNTAIN:
Young fold mountains forms the alpine chains. The Alpine chains are the active mountain making belts and they constitutes the narrow zones most of which lie along the continental margins. The mountains in these belts were formed during the Cenozoic era. They are curved and each curve is called an alpine arc.
These arcs are linked in sequence to form two principal mountain belts as follows;
i. Circum-pacific Belt
This rings the Pacific Ocean. In the North and South America, this belt is largely on the continents and includes Andes and Cordilleran ranges. In the western part of the Pacific Ocean they take form of island arcs running through Aleutians, Japan and the Philippines.
ii. Eurasian-Indonesian Belt
This starts from the west at Atlas Mountains in North Africa, through the near East and Iran to joint Himalayas. Then it continues to south eastern Asia into Indonesia where it meets the circum-pacific belts.
II: DISTRIBUTION OF OLD MOUNTAIN
The fold mountains have distributed worldwide eg. Appalachians in North America (U.S.A), Rocky in N/America, Himalayas in Asia, Alps in Europe, Atlas in North Africa, Cape Ranges in South Africa, and the Great Divide Ranges in Australia.
In general, these distributions consist of two belts which were formed during Paleozoic and Mesozoic eras. Most of them are remnants or roots of old fold mountains.
They are also categorised into two groups;
i. Mountains formed during the Caledonian progeny
It extends from Northern Ireland through Scotland into Scandinavia. Caledonian mountains are remnants of this system.
ii. Mountains formed during the hercynian orogeny
In N/America it consists of Appalachian mountain and in Europe it extends from British Isles to Northern Europe. Hercynian system also exists in Russia where there are Ural mountain ranges and South Africa where there are Cape ranges.
SIGNIFICANCE OF FOLD MOUNTAINS
1. Climatic modifier
The regions on one side of a mountain range may have an entirely different climate from that of the region on the other side. The coastlands of British Columbia have mild winters, warm summers and rains through the year. To the east of the Rockies the prairies have cold winters, hot summers and there is a maximum of rain in the summer.
2. Source of major rivers
Fold mountains often receive heavy rain and/or snow which may give rise to important rivers eg. Ganges and Indus Rivers in India starts from mount Himalayas and Tennessee Rivers in North America from Appalachians mountain.
3. Source of timber
Some mountains ranges have valuable timber resources eg. coast ranges of western America is the source of coniferous soft wood, foothills of the Himalayas is a source of teak.
4. Attractive landscape for tourist
Good scenery of Alps mountains in Switzerland with snow cover and other related features found in glaciated areas attract tourists.
5. Mineral deposits
Some minerals and their plateaus contain minerals eg. Nevada (Copper and gold), Bolivia (tin), etc.
WARPING / VERTICAL MOVEMENT
Warping is the vertical movement of the earth crust either upwards or downwards, without breaking or faulting.
The warping process refers to as the Epeirogenic forces.
Up warping: This involves upwards movement of the crust for a few meters.
Down warping: This involves the subsidence or down ward movement of a block of land.
TYPES OF WARPING
There are two (2) types of warping depending on the types of movement. These are;
Up warping (Upward): Is the movement where by the crust moves up lifted.
Down warping (Downward): Is the movement where by the crust moves down lifted.
EFFECTS OF WARPING ON LANDSCAPE
The following landforms are responsible due to warping process. These are;
1. Basin (Depression):
This is a large size hollow on the earth’s surface formed due the influence of down warping process of the earth’s crust. Some of the depression are occupied by water to form extensive saucer shaped lakes. Example: Lake Victoria, and Lake Chad in Sudan.
2. Plateau:
This is the flat-topped surface, up land with flanking plains formed due to the influence of the upwarping process on the earth’s crust.
3. Dome (Diapir):
A dome refers to the up lands, rounded hill like feature formed as a result of vertical uplifting of landforms.
FORMATIONS OF MOUNTAINS (MOUNTAIN BUILDING)
A mountain can be defined as a part of the earth surface which is elevated higher above the flanking surrounding plains. In general, mountains are land with height exceeding 1500metres above the surrounding land.
Mountains defer from high lands and the hills while the hills are elevated land of at least 300 meters (1000feets), the high lands are elevated land of at least 1000meters. Within the high lands there are mountains eg. Mount Kilimanjaro and Elgon in East African high lands.
TYPES OF MOUNTAINS
There are different types of mountains in which differ according to their process of formation.
The basic types are: –
1. Residual mountains:
These are mountains formed when area of upland remains upstanding above the general ground level of the land after denudation processes have affected and lowered the land surface. These mountains appear isolated peaks on peneplain or in the open deserts.
Excellent example of residual mountain is inselberg eg. the Sierra mountains in Spain.
2. Volcanic mountains:
These are conical shaped like volcanoes with craters on their top. They are formed due to accumulation of lava on the earth surface. Depending on kind of lava, volcanic mountain differs in their shape and size. Majority of volcanic mountains occur along the plate tectonic boundaries. Excellent example; Mount Kilimanjaro and Oldoinyolengai in Tanzania.
3. Block mountains / Fault-block / Horst mountains:
These mountains are flat topped upland formed by process of faulting. These are the result of either tensional or compressional forces associated with plate movement. Excellent example of block mountains includes the Vosges and Black forest mountains in Europe, and Ruwenzori in East Africa in Uganda.
4. Fold mountains:
These are mountains commonly found along the convergent plate boundaries. They are formed due to folding process caused by tremendous compressional forces affected the earth crust. Excellent examples of fold ranges include the Andes in S/America, Rocky in N/America, Alps in Europe and Himalaya (Everest mts.) in Nepal in Asia
CLASSIFICATION OF MOUNTAINS
The mountains can be classified on basis of different criteria such as height, location, mode of formation and period of origin like as follow;
1. On the basis of height
The mountains can classify into;
- Low mountain which range between 700-1000m.
- Middle (rough) mountains which range from 1000 to 1500m.
- High mountains which range from 1500m and above.
2. On the basis of location
The mountains can classify into;
- Coastal mountains eg. Appalachians, Rockies, and Alps mountains.
- Inland mountains which formed on the adjacent land mass eg. Ural mountain in Russia, Vosges and Black forest block mountain in Europe. Coastal and inland mountains called continental mountains.
- Oceanic mountains, these mountains their root below the water surface or below sea level such as mid-oceanic ridges. Eg. MidAtlantic oceanic ridges.
3. On the basis of mode of formation (origin)
There are tectonic mountains formed due to tectonic forces. They can classify into;
- Fold mountains formed due to compressional forces eg. Alps mountain.
- Block mountains formed due to tensional forces eg. Ruwenzori mountain.
- Volcanic mountains formed due volcanic eruptions eg. Kilimanjaro Mountain. It is also called mountains of accumulation.
4. On the basis of period:
The mountains can classify into;
- Pre-Cambrian mountains include the Laurencin orogeny which took place during preCambrian era 3000 million years ago in Archaeozoic period, most of them are eroded now. Example pen plain of Canadian shield and Akwapim Hills in South Ghana.
- Caledonian mountains (orogeny). These took place in the Paleozoic era between 500-350 million years ago. Eg. the Scottish Highlands and Scandinavia mountains.
- Hercynian mountains. Took place between the late Paleozoic and Mesozoic era between 350-240 million years ago. Eg. the Cape Ranges of South Africa, Appalachian Mountains in N/America, Ural Mountains in Russia and Welsh Mountains in Britain.
- Alpine mountains. It is recent building, formed during Cenozoic era 300 million years ago. These are highest and most impressive mountains in the world. Eg. Alps, Atlas, Rockies, Himalaya and Andes mountains.
MOUNTAIN BUILDINGS / MOUNTAINS FORMATION
Mountain building is the geological processes that underlie formation of mountains.
Generally, process of mountains building is referred as “orogenesis” from Greek word “oros” which means mountains “genesis” which means formation. The responsible forces of mountain building are endogenic forces such as epeirogenic forces, orogenic forces and volcanism. There are several theories describe the mountain building.
THEORIES OF MOUNTAINS BUILDING
The principal theories on mountain building are: –
1. Isostatic theory
This theory put forward by various scholars such as Dutton, G. Everest, G. Airy, etc in
1955. The theory explains formation of mountains by Isostatic adjustment and disturbance movement. For instance, at first denudation can affect the land surface leading to the formation of residual mountains. The unloading process can trigger off vertical and horizontal movement below the surface responsible to the formation of folds, cracks, and faults.
These are responsible to upwelling forces with formation of dormant mountains, folding forces with fold mountains formation and faulting process with formation of Block Mountains. The adjustment process can lead to the upwelling of molten materials which reach the earth surface leading to formation of volcanic mountains.
Strengths of Isostatic theory;
• It clearly explains the formation of all mountain types.
2. Plate tectonic theory
This theory of mountain building was provided in 1960’s by several scholars like Mathew, R. Parker, etc.
The theory is the continuous of Wegener hypothesis of continental drift theory in 1915. This theory states that, plate tectonic movements as the cause of mountains building. For instance, when plate converge there occur folding process with formation of fold mountains like Himalaya in Asia and Andes in S/America.
Moreover, subduction process may create faults and cracks which leads to upwelling of molten materials responsible to the formation of volcanic mountains. The divergent and transform movements of plates leads to intensive energy with formation of cracks and faults may responsible to the formation of fault block mountains eg. Ruwenzori mountain.
Strength of Plate tectonic theory;
- It explains the distribution of volcanic mountain, fold mountain, block mountain along the tectonic boundaries.
- It explains the influence of earth movement in formation of endogenic forces responsible to the formation of mountains.
Weakness;
It does not explain the formation of residual mountain.
3. The sea floor spreading theory
This theory was provided in 1960’s by American’s scientist named Harry Hess of Princeton University.
This theory presupposes that, mountains are formed when the sea floor spreading a part due to convectional currents in the asthenosphere. The molten materials upwelling penetrating the lines of weakness in the lithosphere and solidify on the earth surface as volcanic mountains or on the sea floor as sea mountains.
Occurrence of cracks and faults as the crustal block diverge may lead to the formation of fault blocks mountains on the land surface near to the rift valley. This explains why block and volcanic mountains occur closely near by the rift valley eg. Kilimanjaro, Elgon, Ruwenzori, etc.
Some times upwelling of magma may lead to vertical movement beneath crustal rocks and therefore resulting to the formation of dormant mountains.
Strength of the theory:
- It explains why rift valley and mid oceanic ridges are associated with the formation of block, dormant, and volcanic mountains.
- It explains formation of volcanic sea mountains along mid oceanic ridge.
Weakness;
- Failure to explain the formation of residual and fold mountains.
4. Continental drift theory
This theory explain that when the continents were forming, the Indian continent drifted towards the Eurasia, the crust together with the sediments between were squeezed to form fold mountains eg. Himalaya ranges. This supported by the presence of marine limestone rocks at the summit of Mount Everest.
5. Contraction theory
This theory explains that mountains were formed during the formation of the earth, when molten rocks were cooling. The surface rocks cooled and contracted faster than those of interior. Since the interior was cooling at a lower rate the surface rocks started to wrinkle in order to fit on the cooling and contracting rocks of the interior.
6. Convectional current theory
The theory states that when the convectional currents in the mantle move horizontally, they cause a fractional pull to the crustal rocks making them move. When the convectional currents are pulled towards each other hence fold mountains occur.
7. Geosyncline theory
It is also known as geosynclinals orogen theory. The theory was introduced by German geologist Kober. According to him, the mountain ranges are formed as result of compression of geosyncline situated on the margin of forelands of ancient rigid landmasses. He referred these has border ranges.
8. Denudation theory
This explains that, some mountains are formed when resistant mass of rock remain standing after denudation has taken away the surrounding soft rocks. This explains the formation of residual mountains like Sekenke hill in Singida in Tanzania.
GEOGRAPHICAL IMPORTANCE OF MOUNTAINS
1. Source of minerals
Some mountains are sites of valuable minerals. For example, the domal mountain of the Dakota in U.S.A is the site for gold deposits. The volcanic highlands are sites of diamond and gold.
2. Source of tourist attraction
Mountain provide beauty for tourists. For example, Kilimanjaro and Himalaya Mountains.
In this case, they are source of capital revenues.
3. Source of river
Many mountains and highlands are source of rivers eg. the river Rhine in Europe originate from fold Alps mountain, the Pangani river in Tanzania has its source from Kilimanjaro mount.
4. Climatic influence
Mountains and highlands make their own climatic characteristics with heavy rains, low temperature and high humidity. Eg. Arusha region in Tanzania.
5. Source of timber and forest reserves
Obviously most of world timber and forest reserves are sited along mountains and highlands.
REASONS FOR WHY MOUNTAINS MAKES THEIR OWN CLIMATE
i. Have their own type of rainfall known as orographic rainfall (relief rainfall) which is very difficult to be found on other localities. Example this type of rainfall found in Eastern part of Mount Kilimanjaro in Tanzania.
ii. Control its own kind of temperature where temperature decreases with increasing of altitude, this process in known as temperature lapse rate, that’s why in many highly mountain peaks there are snow cover like at Kilimanjaro mountain. Temperature falls for every 100m per 0.60C.
iii. Have their own type of wind which only tied up on such locality example anabatic winds and katabatic winds which frequently blows up and down mountain valleys.
iv. Mountain control the humidity of a place where by the moisture increases or decreases as you go up or down of the mountain, remember below the mountains amount of moisture very high unlike on the mountain peak.
v. Mountain control its own vegetation belts which are specialized on those environments where mountains are found. Example the vegetation belts tend to varies starting from grassland, thickest to the woodland as trees species arrange themselves from mountain valleys to the mountain peaks.
v. Mountain control its own atmospheric pressure system, where by decreases with increasing the height and decreases foot ward the mountain, etc. Pressure decreases for every 100m per 10mb.
REVISIONS QUESTIONS
1. Describe six features associated with fracturing of the crustal rocks.
2. Describe the various landforms associated with faulting process (Necta, 2001)
3. Wrinkling of the earth’s crust is paramount important in description of landforms. verify
4. Mountain building is the geological processes that underlie formation of mountains. Explain five theories of mountain building
Qn: Mtaalamu, Sebastian once remarked that, “Mountains makes their own climate”. Justify.
5. Basing your discussion on the nature of their formation, attempt a classification of mountain types. (Necta 1977, and Necta 1980)
6. Examine the nature and distribution of the world major fold mountain system (Necta 1975; necta 1984 and 1987)
7. Describe nature, distributions and significance of Fold Mountain.
8. Describe direct and indirect effects associated with faulting.
9. Folds appears in different shapes. Validate this statement with six points.
10. “Mountain building classification is based of varied criteria such as height, location, mode of origin and period of origin”. Justify
11. Diastrophism is the process involves vertical and lateral movement of tectonic plates that leads to earth’s dynamism. Give six proofs based on landscapes related to that process.
12. With specific examples, discuss the effects of diastrophism on the earth’s surface (Necta 1978)
13. Evaluate the environmental impacts of diastrophic activities.
14. A farming community is located in a valley shaped by folding a) How does its geological structure affect soil quality? (b) What possible agricultural practice would be most effective in the environment?
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