Mass movement

Mass movement can be defined as the movement of weathered materials (regoliths) on slope under the force of gravity. It can also be referred to as the movement of rock materials from one place to another under the influence of gravity.

Factors Affecting Mass Movement

These are factors that affect mass movement:

• Gradient of the slope
• Human activity
• Natural and weight of materials
• Pressure of lubricating moisture
• Presence of vegetation

1. GRADIENT OF THE SLOPE: The gradient of the slope is one of the most important factors that affects mass movement. For example, rock materials move faster in steep slopes or hilly areas than in gentle slope.
2. HUMAN ACTIVITIES: The activities of man like construction, farming/agriculture, grazing, mining on the slope of mountains or highlands to promote or reduce the movement of rock materials.
3. NATURE AND WEIGHT OF MATERIALS: it is noted that the loose rock materials tend to move faster than tightly held materials, i.e. the heavier the weight of the materials, the slower the movement.
4. PRESSURE OF LUBRICATING MOISTURE: The presence of lubricating moisture like rain water, ice etc, tends to produce, promote or increase the movement of rock materials down the slope.
5. PRESENCE OF VEGETATION: The presence of vegetation can either increase or reduce the movement of rock materials.

TYPES OF MASS MOVEMENT

There are two main types of mass movement

• Slow movement
• Fast movement

1. SLOW MOVEMENT: They are more effective in areas of chemical weathering. There are three most important which are (i) Soil creep (ii) Tallu creep (iii) Solification

SOIL CREEP: It is a slow, almost unnoticeable continues movement of weathered materials down a slope under the influence of gravity.

It operates on a very gentle slope and the speed of the movement would be as slow as 1cm per year. This movement is aided by water which acts as a lubricant which enebles rock materials to creep over each other. Alternative wetting and drying, heating and cooling of soil etc. are other factors that influence soil creep.

Soil creep can be noticed when fence or trees bend towards the direction of movement of the soil in a gentle slope, electric and telegraphy pole are titled, vertical rock layers are covered down slope, leaning on tree trunks and down slope, bulging of walls and fences soil accumulated behind walls which may collapse as a result of the soil erosion.

TALUS CREEP: This is less perrasive thin soil creep. Talus creep is the movement of angular rocks down moderately through steep slopes. Large talus creep move enmass especially in mountaneous region where freeze – thaw action is frequent.

SOIL SLOPE: This is a slightly faster movement usually are raging 5cm and 1m a year on moderate slopes. It occurs on temperature and polar regions. During the winter, the whole ground is frozen. In the summer, the surface layers thaws while the ground is still frozen. The saturated top soil may now begin to move on active layer over the frozen sub – soil.

2. FAST MOVEMENT – TYPES
3. Land slide (ii) Rock fall (iii) Earth flows and mud flows

LAND SLIDE: This takes place when large quantities of loosed surface rocks and soil suddenly slide down and the steep slope such as a cliff face, a valley’s side or embanment.

Land slides are caused by the lubricating acting action in water and pull off gravity. The actions that help to produce a land slide are the undercutting of the base of steeps slope by a river or sea or by human action. They are often treggared off by an earthquale or by prolong erosion.

ROCK FALLS: This refers to a mass of rock which falls from a steep cliff. This type of mass wasting is the most rapid of it.

When this continues for a long period of time, the broken rock coils at the base of the slope in mould.

EFFECTS OF MASS MOVEMENT

• It can lead to loss of farmland
• It can lead to displacement of settlement
• It can cause destruction of transportation network
• It can lead to tilting of electric and telegraphy poles
• It can cause the damage of rivers
• It leads to loss of soil fertility

MAJOR ROCK TYPES IN HIGHLANDS

1. North central plateau, Western highlands/uplands, Mandara Mountain, Sheshi, Alantika, Obudu and Oban hill.
2. Jos plateau
3. Udi Hill

IMPORTANCE OF HIGHLANDS

1. Sources of minerals
2. They serve as tourist centres/attractions
3. They serves as source of rivers e.g. River Hadeijia, River Kaduna, River Gana, River Gurara take their source from North – central highlands
4. Some of them are good for settlement e.g. Jos Plateau
5. For construction of hydro-electric power e.g. Kanji Dam
6. They serve as wind breakers. Some mountains, as a result
7. Formation of rain
8. For transhumance

PROBLEMS ASSOCIATED WITH HIGHLANDS

1. They prevent human habitation
2. Barrier to communication
3. Highlands encourages soil erosion
4. Mountains soil are poor in nutrients
5. Mountains atimes occupy good lands.

DRAINANGE OF NIGERIA

Drainage can be simply referred to as the water bodies like rivers and lakes

1. RIVERS IN NIGERIA: Nigeria is drained by two main rivers; River Niger and River Benue.

River Niger, is the largest river in Nigeria which takes its source from Guinea highland or Futa jallon highland in Guinea. River Niger passes through Mali and Niger Republic of Nigeria.

River Benue, has its source from eastern hihglands and joins the Niger at Lokoja. This makes Lokoja to be referred to as a confluence town.

1. OTHER RIVERS: Other rivers in Nigeria, takes their sources from highlands in Nigeria. These are:
2. North – Central Highlands: The North – central highland have such rivers as Kaduna, Hadeija, Zamfara, Yobe, Ghana, Gongola and Rima.
3. Western Uplands/Highlands: They have rivers such as Ogun River, River Osun and River Osse which flows directly into the Atlantic Ocean.
4. Eastern Highlands: The eastern highlands have rivers like Donga and Katina – Ala.
5. Eastern Scarplands: The eastern scarplands have river like River Anambra and Cross Rivers.

Characteristics of Nigeria Rivers

1. The volume of the rivers changes with season i.e. during rainy seasons, the volume of the water increased and it decreases during dry seasons.
2. Presence of rapids and cataracts: Most Nigerian rivers have rapids and cataracts which hinders or disturbs in land navigation or transportation by water.
3. Presence of debrils: Most Nigeria rivers do carry a lot of debril along with itself like dead leaves mud, wood etc when they flow through the forest.
4. Shallowness: Most rivers are very shallow and full of silt.
5. Seasonality: Most Nigerian rivers flow during rainy season but stop or reduce flowing dry season.
6. Colour changes with season: The rivers have muddy and dirty colour during rainy season but remain dear and clean during dry season.
7. Specific direction of flow: Most Nigeria rivers in the south flows in the North – South direction into the sea while rivers in the North flows in a radiant pattern.
8. Short course with high speed: Most Nigerian rivers are very short and flow rapidly e.g. Ogun, Osun and Cross River.

IMPORTANCE OF NIGERIA RIVERS

• Means of transportation
• They serve as source of food supply
• Generation of Hydro electric power (HEP) e.g. Kanji dam and Shiroroda
• They are good for domestic use e.g. cocking, bathing and washing
• Provision of employment e.g. serve as revenue generation of fishermen
• They can be used for irrigation purposes
• For tourism
• For sports and game.

Problems Encountered in the Utilization (Uses of Nigerian Rivers)

1. Season fluctuation of the water volume
2. Rapids and fall of the rivers
3. River pollution / water pollution
4. Shortness of the rivers
5. Silting at the mouth of the river
6. Narrow channels.

RIVER BASINS

River basins simply refers to the area generally drained or levelled by a river and its main tributaries. In Nigeria, there are five main river basins:

• The Niger basin
• The Benue basin
• The Cross River basin
• The South – Atlantic basin

The river basins can be classified into three:

1. Large basins with long rivers: These are rivers that flow over a long distance and empty their water into the Atlantic Ocean e.g. River Benue and River Niger.
2. Short river basin with small basin: These are rivers that flow from a short distance before emptying their water into a larger body such as River Osun, River Ogun, River Osse and River Ossiomo
3. Rivers in basin of Inland drainage: The rivers that exist in this area do not have access into the Atlantic Ocean but flow into lake Chad. Examples are River Hadeija, River Kamadugu, River Gana, River Yediseram, River Katogun etc.

ECONOMIC IMPORTANCE OF RIVER BASINS

1. River basins provides good sites for settlement
2. River basins provides medium of communication transports from one place to another.
3. River basins provides both domestic and industrial water supply
4. River basins usually provide good fishing ground for its inhabitants
5. River basins are usually suitable for agricultural purposes
6. River basins provide a lot of mineral deposits.

LAKES

A lake can be defined as a body of water surrounded by land. Lakes in Nigeria can be grouped into the main bodies:

1. Artificial or Man-made Lake: This type referred to as artificial lakes are constructed by man as a result of improving in science and technology for this reasons:

• Irrigation (Agriculture)
• Hydro – electric power generation

Examples are the Kanji lake along River Niger and the Shiroro lake along River Kaduna.

2. Natural Lakes: These are lakes that exist naturally without man having anything to do with them. For example Lake Chad – often referred to as an inland drainage because several rivers flow into it without getting out.

IMPORTANCE OF LAKE

• For employment
• For irrigation
• Provision of food
• Tourism
• Industrial and domestic purposes
• For transportation