PHYSICAL GEOGRAPHY
TWO FACTORS WHICH PROMOTE RAPID CHEMICAL WEATHERING IN THE TROPICS ARE
A. high temperature and extreme aridity B. high temperature and low humidity C. low temperature and high humidity D. high temperature and high humidity ✓ E. high temperature and low rainfall In the tropics, rapid chemical weathering is promoted by high temperatures and…
THE WEARING AWAY OF THE SIDES AND BOTTOM OF A RIVER’S CHANNEL IS CALLED
A. hydraulic action B. corrosion C. attrition D. corrasion ✓ E. solution The wearing away of the sides and bottom of a river’s channel is called corrasion. Corrasion, also known as abrasion, is the process by which the river’s load of sediment wears…
HOW WERE THE MAJOR MOUNTAIN BELTS OF THE WORLD PRODUCED
A. By wind erosion B. By Folding ✓ C. By glacial erosion D. By weathering E. By river deposition The major mountain belts of the world were primarily produced by folding, a geological process that involves the bending and deformation of rock layers…
POLLUTION OF WATER RESOURCES
Man cannot survive without water. The low population densities in the desert natural region is because of the water deficiency which renders vast areas of land uninhabitable. The sources of water include oceans, rivers, lakes, rainfall and groundwater. Unfortunately, man…
COASTAL FEATURES OF EROSION
1) Capes and bays: On exposed coasts, the continual action of waves on rocks of varying resistance causes the coastline to be eroded irregularly. This is particularly pronounced where hard rocks, e.g. granites and limestones, occur in alternate bands with…
THE MECHANISM OF MARINE EROSION
The most powerful agents of marine erosion are waves. Their origin is due to the sweeping of winds over the water surface, which sets a series of undulating swells surging forward. These become higher and swifter. A normal wave in…
THE ACTION OF WAVES, TIDES AND CURRENTS
The action of the wind passing over a stretch of sea causes waves to develop and when the waves reach the coast they cause erosion or deposition. Wind passing over water sets up turbulences, which causes ripples and then waves…
RIVER REGIMES
The seasonal variation in the volume of water in a river is known as the regime. A knowledge of the regime of a river is important to man in controlling possible floods, storing up water for irrigation and human consumption,…
GREAT CIRCLE ROUTES
Since the earth is spherical in shape, the shortest distance between any two points on the globe lies along its circumference. There are an infinite number of great circles of equal length running around the globe, e.g. the circle formed…
THE TROPICAL MONSOON AND TROPICAL MARINE LANDS
Distribution Some parts of the world experience seasonal winds like land and sea breeze but on a much larger scale. These are the tropical monsoon lands with on-shore wet monsoons in the summer and off- shore dry monsoons in the…
THE EQUATORIAL REGIONS
Distribution The equatorial, hot, wet climate is found between 5° and 10° north and south of the equator. Its greatest extent is found in the lowlands of the Amazon, the Congo, Malaysia and the East Indies. Further away from the…
THE ARCTIC OR POLAR CLIMATE
Distribution The polar type of climate and vegetation is found mainly north of the Arctic Circle in the northern hemisphere. The ice caps are confined to Greenland and to the highlands of these high-latitude regions, where the ground is permanently…
EARTH ENERGY SYSTEM
Insolation The only source of energy for the earth’s atmosphere is the sun which has a surface temperature of more than 5982°C (10 800°F). The energy travels through space for a distance of 150 million km (93 million miles) and…
LANDFORMS OF GLACIATED LOWLANDS
Landforms of glaciated lowlands are mainly depositional in nature, brought about by both valley glacier and continental ice sheets. The former leave behind the eroded material in only restricted areas. The imprint of ice sheets on the landscape is far…
LANDFORMS OF HIGHLAND GLACIATION
Glaciation generally gives rise to erosional features in the highlands and depositional features on the lowlands, though these processes are not not mutually mu exclusive because a glacier plays a combined role of erosion, transport and deposition throughout its course.…
THE ICE AGE
During the earth’s history, there have been many changes in the pattern of climatic regions. The most recent change came about as a result of a fall in temperature over the whole of the earth’s surface, so that the area…
CLIMATIC EFFECTS OF OCEAN CURRENTS
1) Temperatures: Coastlands with warm currents offshore tend to have mild climates for their latitudes. Coastlands with cold currents off-shore are cooler than they would otherwise be. The effect of a warm current off-shore is especially pronounced if the prevailing…
THE CIRCULATION OF THE PACIFIC AND INDIAN OCEAN
The Circulation of the Pacific Ocean The pattern of circulation in the Pacific is similar to that of the Atlantic except in modifications which can be expected from the greater size and the more open nature of the Pacific. The…
THE CIRCULATION OF THE ATLANTIC OCEAN
Let us now study more closely the circulation of ocean currents in the Atlantic Ocean. We shall begin with the North and South Equatorial Current at the equator. The steady Trade Winds constantly drift two streams of water from east…
THE MOVEMENT OF OCEAN CURRENTS
Ocean currents are large masses of surface water that circulate in regular patterns around the oceans, as shown in the world map in Fig. 12.9. Those that flow from equatorial regions polewards have a higher surface temperature and are warm…
THE TEMPERATURE OF OCEAN WATER
Like land masses, ocean water varies in temperature from place to place both at the surface and at great depths. Since water warms up and cools down much more slowly than the land, the annual range of temperature in any…
SALINITY OF THE OCEAN
Almost every known chemical element can be found in varying proportions in the oceans whose most characteristic feature is their salinity, in contrast to the fresh water of lakes and streams. All sea water of which sodium chloride or common…
THE RELIEF OF THE OCEAN
The ocean basins are in many ways similar to the land surface. There are submarine ridges, plateaux, canyons, plains and trenches. A section drawn across an ocean (Fig. 12.4) illustrates the typical submarine relief features. 1) The continental…
EXPLORING THE OCEANS
The oceans occupy more than 70 per cent or 364 million sq km (140 million square miles) of the earth’s total area of 510 million sq km (197 million square miles). They have tremendous development potential. Besides being a source…
LANDFORMS DUE TO WATER ACTION IN THE DESERTS
Wind erosion, transportation and deposition are most effective and widespread in desert regions, but few deserts in the world are entirely without rain or water. In some deserts, there are perennial rivers such as the Nile in Egypt which has…
LANDFORMS OF WIND DEPOSITION IN DESERTS
Materials that have been eroded and transported by winds must come to rest somewhere. The finest dust travels enormous distances in the air, and may be moved completely out of the desert. It has been estimated that some dust grains…
LANDFORMS OF WIND EROSION IN DESERTS
In the combined processes of abrasion, deflation and attrition, a wealth of characteristic desert landforms emerge. 1) Rock pedestals or mushroom rocks: The sand-blasting effect of winds against any projecting rock masses wear back the softer layer so that an…
THE MECHANISM OF ARID EROSION
Arid landforms are as a result of many combined factors, one reacting upon the other. Insufficient rainfall, often less than 127 mm (5 inches), coming at most irregular periods, coupled with very high temperatures (31°C/87°F, is the average) and a…
TYPE OF DESERTS
About a fifth of the world’s land is made up of deserts, some rocky, others stony and the rest sandy. Deserts that are absolutely barren and where nothing grows at all are rare and they are better known as ‘true…
IRON AND STEEL
Nature, properties and uses Iron is the commonest, cheapest and most versatile of all metals. It is, in fact, the basis of the modern industrial complex, About 90 percent of the world’s iron ore is used in the making of…
ELECTRICITY
Of the power sources, electricity is the cheapest. It is not exhaustible like coal or petroleum but is renewable. The French have aptly described it as ‘white coal’. There are two different sources of electricity. That which is derived from…
PETROLEUM
Petroleum is mineral oil, organic in origin, and occurs in the pore spaces of sedimentary rocks. It is derived from the decomposition of marine or vegetative matter. It normally occurs in dome-shaped anticilines, between layers of non-porous rocks. The oil…
COAL
Coal, comprising mainly carbon of vegetative origin, is one of the oldest forms of power. It provided the basis for the Industrial Revolution. Its importance as both fuel and raw material was greatly enhanced with the invention of the steam…
INTRODUCTION TO MINING AND POWER
Minerals are natural, chemical substances which make up the rocks of the earth’s crust. They have certain physical and chemical properties that differentiate them from one another. There are well over 2 000 known minerals scattered very unevenly throughout the…
SOME VOLCANIC ERUPTIONS AND DISTRIBUTION OF VOLCANOES IN THE WORLD
In the history of mankind perhaps the most disastrous eruptions were those of Mt. Vesuvius, Mt. Krakatoa and Mt. Pelee. Mt. Vesuvius Mt. Vesuvius, standing 1200m (4000 feet) above the Bay of Naples, erupted violently on 24 August A.D.…
CORAL REEFS
In tropical seas many kinds of coral animals and marine organisms such as coral polyps, calcareous algae, shell-forming creatures and lime-secreting plants live in large colonies. Though they are very tiny creatures, their ability to secrete calcium carbonate within their…
THE FORMATION AND ORIGIN OF LAKES
Lakes are amongst the most varied features of the earth’s surface. They occupy the hollows of the land surface in which water accumulates. They vary tremendously in size, shape, depth and mode of formation. The tiny ones are no bigger…
ISLANDS
An island is a piece of land surrounded on all sides by water. It may occur individually or in a group, in open oceans or seas. Smaller ones of only local significance are found even in lakes and rivers. Generally…
LAKES AND MAN
A careful examination of the lakes of the world will reveal their immense human significance. In countries where they are found in abundance, such as Finland, Canada, U.S.A ., Sweden and the East African States, lakes, together with other inland…
FACTS ABOUT EARTHQUAKES
An earthquake is defined as a violent tremor in the earth’s crust which sends out a series of vibrating waves in all directions. Causes of Earthquakes Earthquakes occur as a result of disturbances or movements within and below the…
MINERAL RESOURCES
Minerals, unlike other resources are non-renewable resources because once they are exhausted, they cannot be replaced. Mineral resources are grouped into the followings: Mineral fuels such as petroleum, coal and natural gas. Ferrous and non-ferrous metals such as iron, copper,…
VEGETATION RESOURCES
Vegetation resources include all the resources one can get from the forest and savanna for the benefit of man, animals and plants. Vegetation resources include timber, roots, leaves, barks of trees, latex, fruits, fibre, firewood and wild animals. Importance…
WATER RESOURCES
Water resources refer to any useful material (living or non-living) inside water which are of benefit to man, animals and plants. Water resources are some of the most important environmental resources of man. Sources of water: Sources of water include…
ATMOSPHERIC RESOURCES
Atmospheric resources are those elements such as wind, water, sunlight and gases found in the atmosphere which are of benefit to man, animals and plants. Types of Atmospheric Resources Atmospheric gases, e.g. oxygen, nitrogen, carbon dioxide, water vapour, ozone layer…
MEANING OF ENVIRONMENTAL RESOURCES
Environmental resources refer to any useful item in the environment, or materials and substances that are useful to man. In other words, environmental resources are useful things (both living and non-living) occurring naturally within a particular geographical location which are…
ENVIRONMENTAL CONSERVATION
Conservation is defined as the planned, control exploitation or judicious use of natural resources to ensure their continuous availability and to preserve the quality or original nature of the environment. In other words, conservation is the preservation of natural resources…
LITHOSPHERE
Earth’s crust and the interior of the earth: The earth is almost like a sphere. Its radius is about 6,400 kilometres. There is no scope to observe the interior of the earth by piercing the hard external covering. The geologists…
PERIHELION AND APHELION
The orbit of the earth is an ellipse. Its length is 93,80,51,827 kilometres. The sun is located in the centre or in the focus of the ellipse. Perihelion: In the process of revolution around the sun, the earth on 1st…
DIURNAL AND ANNUAL MOTION OF THE EARTH
Everyday the sun rises in the east and sets in the west. This process led many people in the past to think that the sun is moving and the earth is fixed. The sun moves around the earth. But with…
CLIMATIC CHANGE
Climatic change is defined as a change in the statistical properties of the climatic system when considered over long periods of time. In other words, climatic change is a significant and lasting change in the statistical distribution of weather patterns…
