Grade 9 Geography - Unit One PDF

Welcome to Grade 9 Geography  Introduction If you remember, in grade eight you learnt about the physical characteristics of the Earth People and socioeconomic activities natural resources and socioeconomic development, modern history of Ethiopia and contemporary glob...

Welcome to Grade 9 Geography  Introduction If you remember, in grade eight you learnt about the physical characteristics of the Earth People and socioeconomic activities natural resources and socioeconomic development, modern history of Ethiopia and contemporary global issues. In this grade you are going to study about The geography of Ethiopia.  Introduction…. Under geography of Ethiopia you will learn about LOCATION, SIZE AND SHAPE OF ETHIOPIA GEOLOGICAL HISTORY OF ETHIOPIA – Geological processes and the resultant Landforms of Ethiopia (three main physiographic divisions of Ethiopia) CLIMATE OF ETHIOPIA NATURAL RESOURCE BASE OF ETHIOPIA – DRAINAGE SYSTEMS OF ETHIOPIA – WATER RESOURCES OF ETHIOPIA – MAJOR SOILS TYPES OF ETHIOPIA – MAJOR MINERAL RESOURCES AND THEIR DISTRIBUTION IN ETHIOPIA – BIOTIC RESOURCES OF ETHIOPIA ( Vegetation and Wild Life)  …. Before you start studying the above mentioned geographical themes, you will be acquainted/familiarized with some basic concepts related to the science of geography such as the meaning, scope and branches of geography  UNIT ONE GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA  Under this unit you are going to learn 1.1. The Meaning, Scope and branches of Geography 1.2. Location, Size, and Shape of Ethiopia 1.3. Geological History of Ethiopia (more specifically the Geological Processes and Landforms of Ethiopia Objectives / Learning Outcomes: By the end of this unit, you will be able to: Recognize (fully aware of) the concept, scope and branches of geography; Describe the absolute and relative location of Ethiopia; Identify the size and shape of Ethiopia Explain geological processes that shaped the land surface of Ethiopia; and describe different landforms in Ethiopia. 1.1 THE MEANING, SCOPE AND BRANCHES OF GEOGRAPHY Contents to be learn – 1.1.1. The meaning of Geography – 1.1.2. The Scope of Geography – 1.1.3. The branches of Geography Competencies- after the end of this section, you will be able to: – Define geography – Describe the scope of geography – Identify the branches of geography 1.1.1. The meaning of Geography Content: In this lesson, we are going to learn about the meaning of geography. Competencies: at the end of this lesson, you will be able to define geography. Startup Questions discuss on the following questions with your partner What is geography? What does GEO and GRAPHY literally mean? Who defined the term geography for the first time in history? Do you think that geography has a single universally accepted definition? If your answer is no, What reasons do you suggest for the fact that geography has different definitions? Why did different scholars define geography in different ways? An overview In this lesson, you are going to learn about the meaning of geography. First you will learn the general definition of geography. Then there will be a discussion session about the term geography and how it was coined by the famous Greek philosopher known as Eratosthenes. An overview The term “Geography” first appeared in history at the time when the Greek civilization reached its peak. They defined geography for the first time by combining two words of Greek origin namely: Geo and Graphos. → Geo – which means earth → Graphos – which means writing During that time, geography was defined as the field of study which deals with “the description of the earth”. Now this definition seems very general when we compare it to the scope of current geography. Today the scope of geography is beyond this definition. Do you think that geography has a single universally accepted definition? If no why Geography has no single universally accepted definition. Different scholars have defined geography differently at different times. The most important definitions are Geography is the description of the earth (Eratosthenes -276 to 196 BC). Geography is a synthesizing discipline to connect the general with the particular through measurement, mapping, and a regional emphasis (Alexander Von Humboldt -1769 to 1859) Geography is the science of the earth’s surfaces (Concise Oxford Dictionary -1964) Geography is a branch of knowledge that is concerned with the provision of an accurate, orderly and rational description of distributions on the surface of the earth (Hartshorne, R. 1899-1992)  …. Geography is a science that is concerned with the rational development and testing of theories that explain and predict the spatial distribution and locations of things and phenomena on the surface of the earth (Yeates, M. 1968) Each of the above definitions includes the idea that geography studies the earth and Most of them specify the surface of the earth. Why did different scholars define geography in different ways? It is difficult to forward a definition acceptable to all geographers at all times and places. This variation in definition might be attributed to: – the dynamic nature of the discipline and – The wider nature of the scope of geography and the changes in its scope and method of study. Although geography has been defined in different ways by different scholars/geographers. The following is widely accepted definition of geography “Geography is the scientific study of the Earth that describes and analyses spatial and temporal variations of physical, biological and human phenomena, and their interrelationships and dynamism over the surface of the Earth.”  Geography is the study…of the spatial variation of phenomena on the earth’s surface, on the one hand, and the two-way relationship existing between humankind and the environment, on the other hand and their causes and effects The spatial distribution of phenomena on the earth’s surface and The two-way relationship between humans and nature are the core issues in geography Geography focuses on causes, effects, and interactions of physical and human features on the surface of the earth The geographer’s major interest is to explain the spatial variation and distribution of different phenomena over space. Stabilization A number of geography definitions have been given by different scholars of the 19th and 20th centuries. Geography is a branch of science that studies the spatial variation of phenomena on the earth’s surface and the interaction of natural and human features and their causes and effects. Geography being a science uses observation, systematic description, systematic recording and mapping to gather and analyze information  Evaluation What is geography? Who introduced the term geography for the first time in history? Write the modern and ancient definitions of geography. What do we mean by spatial variation of phenomena? 1.1.2 The Scope of Geography Startup questions – What do we mean by scope? – What is the scope of Geography? – How wide is the scope of geography? – Explain the major issues that geography deals with. – What is the major interest of geography? – What are four spheres of physical geography? What makes geography a broad discipline than any other subject? Presentation Scope refers to the content (how broad or narrow) of the field of study of a given discipline. The scope of Geography is – very wide and broad – Dynamic - often changes as discoveries and ideas enter the field. Geography studies a great deal with many physical and human features of the world. Geography examines features in the hydrosphere, atmosphere, lithosphere, biosphere and anthroposphere. ,,,,, Hydrosphere – it includes all the bodies of water, i.e., oceans, rivers, lakes and others. Biosphere – refers to all living organisms in and on the earth’s surface. Atmosphere – it includes all aspects of air composition surrounding our planet. Lithosphere – it is the solid layer of rocks that covers the entire surface of the planet. Anthroposphere – it is the part of the environment that is made or modified by humans – human made environment  The concern of Geography Geography as a field of study is also concerned with: The economic, social, political and ecological problems that you hear every day. It is also concerned with modern technology, such as computers, Global Positioning System (GPS) and Geographic Information System (GIS) to analyze information and draw conclusion with accuracy Do you think that the scope of geography is limitless? Geography has a very wide scope, this does not mean its scope is limitless. Although wide in its scope, it has certain areas that it focuses upon. The following are the major areas that geography focuses on: the earth, its movement and its position in the universe different physical features that constitute the earth’s surface, the forces that cause them, their variations from place to place and their changes over time; different relationships between human beings and their natural environment and Also, the interdependence and the impact on each other;  the conditions of the lower part of the …. atmosphere and the subsequent weather and climatic conditions, together with their spatial distribution and variation; the materials that make up the earth and its diverse landforms; and the major economic activities of humans and the impacts on the environment. Therefore, geography deals with an enormous range of phenomena ranging from physical and biotic to human environment. Hence, geography is a holistic discipline of knowledge and research (academics). Stabilization Scope refers to the content (how broad or narrow) of the field of study of a given discipline, The scope of Geography is very wide and dynamic- changes often as new discoveries and ideas enter the field. Geography is a discipline that has a wide scope. This is because it deals with physical, social, and economic aspects of the world. It generally gives special emphasis on the following four major issues: location, spatial relationships, regional characteristics and the forces that change the earth. Hence, the scope of geography emerges from these broader themes.  Evaluation What is scope? What is the scope of geography? Do you think that the scope of geography is limitless? Why or why not? What are the major areas of the study of geography? 1.1.3. Branches of Geography Content: You have studied the definition and scope of geography. Next, you will learn about the main branches of geography and their specialized fields. Competencies: At the end of this lesson, you will be able to identify the branches of Geography. Startup questions What are the two branches of geography? What does physical geography study? List the sub-branches of physical geography? What does human geography study? List the sub-branches of human geography? List the major elements and events available in your surroundings and categorize these elements under physical and human geography. What is the major concern of applied geography? A, Physical geography It studies the distribution of the natural features of the world, such as climate, landforms, soil, vegetation, surface drainage systems, water resources and animals. It also considers the causes, effects and interactions of these features. It is further sub-divided into more specialized fields of study as follows:  … Geomorphology: it is the study of landforms, their distribution, origin and the force that change them. Climatology: studies factors that create the climate and examines the variation and distribution of climate and related causes and effects. Biogeography: generally speaking, it deals with the distribution of plants and animals. Thus it has two parts – phytogeography - deals with patterns of vegetation growth in relation to climate, soil and human activities. – Zoogeography- studies why certain animals live in one region and not in other. In addition, it investigates the migration of animals and the factors that affect their movements.  … Oceanography: studies the location, causes and effects of ocean currents, waves and tides. It also investigates the ocean floor. Soil geography: studies – distribution of various types of soils throughout the world. Soil geography studies – how different kinds of soil influence the type and amount of crops produced in an area. – It also examines how soils are affected by the agricultural activities practiced in an area. Applied geography is concerned with the B. Human Geography It studies the distribution and influence of human aspects of our world, including cultures, population settlement, economic activities and political systems. It is sub-divided into the following specialized fields of study  … Cultural geography: it examines the distribution and interactions of cultures, including peoples’ beliefs and customs. It also examines the movement, expansion and interaction of cultures on the surface of the earth. Population geography: it is concerned with population distribution and factors affecting it. It also deals with birth and death rates, population structure, population movements, house hold size and other related statistical data. Economic geography: it studies production, consumption, exchange, the spatial distribution of goods, services and factors affecting them. Political geography: it deals with the distribution of political systems and the ways people use them to exercise power and make decisions. It also studies topics such as changes in political boundaries, problems of political instability and patterns of voting.  Urban geography: it studies the … development and characteristics of towns, cities and other urban centers. It also investigates where different groups live within a city; why and where slums develop. Historical geography: it is the study of the geography of the past and how places, regions and patterns of human activity have changed over time Geography is interdisciplinary subject Geography has common areas of study with a number of other fields of study. Generally, geography is classified into two broad categories: physical and human. The physical parts of geography are related to the natural sciences and the human aspects of geography are strongly associated with the social sciences Stabilization Geography may be divided into two fundamental branches: Physical and Human Geography. Physical geography studies the distribution of the natural features of the world, such as climate, landforms, soil, vegetation, drainage systems, water resources and animals. And it also considers the causes, effects and interactions of these features. It is sub-divided into the following specialized fields of study: Climatology, Geomorphology, Biogeography, oceanography, soil geography etc Human geography studies the distribution and influence of human aspects of our world, including cultures, population settlement, economic activities and political systems. It is sub-divided into the following specialized fields of study: economic geography, population geography, urban geography, political geography, historical geography, cultural geography etc  Evaluation What are the two major branches of Geography? What do they study? Could you Give examples for both branches of geography  1.2. Location, Size and Shape of Ethiopia Under this section we will learn, the location, size and shape of Ethiopia. Therefore, At the end of this section, you will be able to: describe the absolute and relative location of Ethiopia; and discuss the effects of size and shape of Ethiopia on its sociocultural, political and economic condition. 1.2.1. Location /position of Ethiopia Content : In this lesson, you will learn the location of Ethiopia. Competencies: At the end of this lesson, you will be able to: ➡ describe the absolute and relative location of Ethiopia; ➡ recognize the geopolitical implication of its location  Introduction What is location and How do you express the location of a place? Location is a place where a particular point or object exists. It refers to a particular place or position where an object exists. In spatial distribution, every place has its own particular location in relation to its surroundings. It is very important term in geography, the term location is a much more abstract concept than what an ordinary person knows. It is usually expressed in two ways: relative location and absolute location. … i, Relative location It expressed in relation to the location of other geographic features such as water body, landmass or neighborings It refers to the position of a place in relation to the location of other geographic features. It can be expressed in two ways; namely; – Vicinal location and strategic location. Vicinal location shows the location of a country in relation to neighboring countries Strategic or natural/global location describes the location of a country in reference to water bodies and landmasses (continents) ii, Absolute location – Astronomical location It refers to the exact position a place expressed as a geographical extent in terms of latitudes and longitudes Start up questions Describe relative location of Ethiopia with reference to the – neighboring countries – vicinal location – major water bodies and landmasses – geological describe the Absolute location of Ethiopia with reference to the geographical extent, in terms of – latitudes and longitudes. Can you identify the relative location of your school or residence?  Presentation A. Relative Location of Ethiopia i. Vicinal Location of Ethiopia Ethiopia is a landlocked country that is surrounded by six neighboring countries. These are: Eritrea, Djibouti, Somalia, Kenya, South Sudan and Sudan, in North, Northeast, East and SE, South, West and NW respectively. Ethiopia is located south of Eritrea, west of Djibouti, North west of Somalia, north of Kenya, east of South Sudan, south east of Sudan Figure 1.1: Relative Location of Ethiopia  ii. Strategic Location of Ethiopia Strategic location is also called natural or global location. It can be described in the following ways. Strategically, Ethiopia is found: – in northeastern of (Horn) Africa; – in the Nile Basin; – to the southwest of the Asia – to the south of Europe; – to the northwest of the Indian Ocean; – to the southwest of the Red Sea; and – to the south of the Mediterranean Sea. B. Absolute or Astronomical Location of Ethiopia It is expressed as follows. Astronomically, Ethiopia is located between – 3oN – 15oN latitudes and 33oE– 48oE longitudes As a result, Ethiopia has four extreme points – the Northern extreme tip – Badime in Tigray - 15oN – the Southern extreme tip- Mayale –in Borena - 3oN – the Western extreme tip – Akobo in Gambella- 33oE Figure 1.2: Absolute Location of Ethiopia  The impact of its location on Ethiopia The impact on its climate – Due to its latitudinal location Ethiopia experiences tropical climate. Due to longitudinal extension it has 1hour difference between the most easterly and most westerly points The impact on Socio-cultural aspect due to its proximity to the Middle east, It adopted the major religions of the world like Christianity, Islam & Judaism and It shares linguistic and cultural r/ships with its neighbors  The impact of its location on Ethiopia The impact on Political aspects –strategically- The political history of Ethiopia has been considerably influenced by: – Geopolitical considerations of superpowers. – Adjacency to the Red Sea route- a major global trade route – helped Ethiopia to trade with many Middle east, Europe and Asian countries The Middle East geopolitical paradigms. As a result, it has been exposed for external invasions but, remains free of external domination. c) Stabilization Ethiopia is a landlocked country surrounded by six neighboring countries. These are: Eritrea, Djibouti, Somalia, Kenya, South Sudan and Sudan Relatively, Ethiopia is found south of Eritrea, west of Djibouti, North west of Somalia, north of Kenya, east of South Sudan, south east of Sudan Astronomically, Ethiopia is located between 30 -150 N latitudes and 330 -480 E longitudes Evaluation 1. What is location? 2. How is it described? 3. Where is Ethiopia located relatively? 4. Which neighboring country is located: North of Ethiopia? East of Ethiopia? South east of Ethiopia? South of Ethiopia? West of Ethiopia? North west of Ethiopia? 5. What is the absolute location of Ethiopia? 6. What are the advantages and limitations of Ethiopia’s location? What locational significance does Ethiopia have as a country that is in the Horn and near the Red sea route? …. Which neighboring country shares the longest boundary with Ethiopia? the smallest boundary with Ethiopia? What is the total boundary length of Ethiopia? What is the rank of Ethiopia in terms of boundary length as it compared with its neighbors?  1.2.2 Size of Ethiopia Content; in this lesson we are going to learn the size of Ethiopia. At the end of this lesson, you will be able to: ➡ describe the size of Ethiopia; and ➡ compare the size of Ethiopia with that of other countries of Africa Start up questions What is the size of Ethiopia? Is Ethiopia a large or a small country in comparison with its neighbors? How big is Ethiopia really and Does size influence a country economic growth? What advantages and disadvantages does Ethiopia have because of its size? Discuss the some advantages and disadvantages of large size for a country.  Presentation Ethiopia has a total areal of 1,106,000 km2. It is the tenth largest country in Africa, by covering about 4% of Africa’s land mass It is 25th in world, by covering about 0.7% of the world’s land area It is the 2nd largest country as compared to its neighboring countries It is the largest country in the Horn of Africa The Horn of Africa takes its name from the horn-shaped land formation the easternmost extension of Africa a narrow tip of land in the region of northeastern Africa that protrudes/projecting into the Indian Ocean, separating it from the Gulf of Aden and south of Arabian peninsula home to the countries of Djibouti, Eritrea, Ethiopia and Somalia Table 1.2: Comparison of Ethiopia’s Areal. Size with its Neighbors Source: CSA, 2012 What advantages and disadvantages does Ethiopia have because of its size? The advantages of large size lets Ethiopia to: Enjoy diverse agro-ecological zones, resulting in a wide variety of fauna and flora; have a great variety of natural resources; and be the home of diverse ethnic groups. Have large population size Have Large space for population settlement, for arable land and for agricultural land etc The disadvantages of large size forces Ethiopia to: High cost of infrastructural development – requires great financial power to construct infrastructural facilities;to expensive administrative expenditure; Difficulty of political administration and unity – – challenges for effective administration and socio-economic integration High cost of defense to protect every corner of the country or to protect its sovereignty  Stabilization With a total area of 1,106,000 km2, Ethiopia is one of the ten largest countries in Africa. When we compare its area with that of its neighbors, Ethiopia stands second, next to Sudan, and it is almost 50 times bigger than Djibouti. The large geographical area of Ethiopia has both positive and negative impacts on the socio-economic, political, and natural conditions of the country Large size has both advantages & disadvantages Some of the advantages Some of the are: disadvantages are: High cost of the presence of infrastructural varieties of development. natural resources. Difficulty of different climates political zones. administration Large space for High cost of population defense to settlement, agriculture, protect every arable land corner of the country Evaluation How big the Ethiopia in terms of its total area? What are the merits and demerits of Ethiopia’s large size? 1.2.3. Shape of Ethiopia Content: in this lesson you will learn the shape of Ethiopia At the end of this lesson, students will be able to: ➡ describe the shape of Ethiopia; and ➡ compare the shape of Ethiopia with that of other countries of Africa  Introduction Countries of Africa and the world at large vary not only in location and size but also in shape. Some countries have elongated (linear) shapes, Others have truncated (shortened) shapes and Some countries have nearly circular (compact) shapes There are three theoretical indicators of the compactness of an area Compactness- refers to the deviation of the shape of a country from a circular shape. These are: 1. the boundary - circumference ratio (B/C); 2. the actual area - area of the inscribing circle (A/A’) 3. the area - boundary ratio (A/B); and  Note Theoretical assumption 1 (B/C) and 2(A/A’) above are based on values of 0.5 to 1.5, as deviating only slightly from compact shape or approximately compact shape and a value of 1, as a perfect compact shape, a value near 1 suggests more compactness, smaller/lower value than 0.5, especially as approaches to zero (0)or greater values than 1.5 indicate greater divergence from compactness or reflects tendencies to be elongation or truncation. Theoretical assumption 3 or A/B ratio is based on the value of the areal size per unit boundary length of a country under consideration with other country. The larger the value or The larger the areal size per unit boundary length, the more compact the country is  Start up Questions How do you describe the shape of Ethiopia? Does Ethiopia have similar shape with its neighboring countries? Can you identify the shape of each neighboring countries? How do you compute the compactness of a country What are the advantages and limitations of compact shape?  Presentation Ethiopia has more or less compact (circular) shape – because, the extreme north-south and east-west spans of the country cover comparable distances. The distance from the geographic center of the state to any of the borders does not vary greatly. How do you Compute the compactness of any country? To Compute the compactness of Ethiopia A, Using the boundary- circumference ratio = B/C Step 1: Compute the boundary length of the country under consideration. In our case Ethiopia. Ethiopia shares a total bounder length of 5260km with six neighboring countries It shares the longest boundary length with Somalia (1600km) and followed by South Sudan (1006km) and It shares the smallest boundary length with the Rep. of Djibouti (310km) Table 1.1: Ethiopia’s Boundary Line length it Shared with Neighboring Countries ….. Step 2: compute the value of r based on the assumption that an area of a small inscribed circle is equal to the area of a country under consideration. In our case Ethiopia i.e, – The area of small inscribed the circle, A = r2 – area of a country under consideration – i.e total area of Ethiopia =1,106,000 km2 = 1,106,000 km2 , then divide both sides by Then, r2 =1,106,000/ = 1,106,000/3.14 r2 = 352,229.3 km2 r= = 593.5 Kms  … Step 3: compute circumference of a small inscribed circle (C). i.e C= 2πr - Circumference of Ethiopia (if it were circle) C = 2x3.14x593.5 Kms C = 3727.18km Step 4: calculate B/C ratio i.e B/C ratio = total Boundary length/Circumference = 5260km/3727.18km = 1.41 This value implies that the shape of Ethiopia has a deviation of 41% from the assumed theoretical circular shape it ought to have  b, Using the actual area of a country and the area of the smallest inscribing circle - A/A’ Step 1: Compute the total area of the country under consideration. For Eth = 1,106,000 km2 Step 2: compute the value of r based on the assumption that area of the smallest inscribing circle (A’) touches the north, south, east and west extreme points of Ethiopia has radius of half length of the longest distance between two extreme points. For Ethiopia 480-330=150/2= 7.50 If 10 = 111km 7.50 = ? , then by crisscross multiplication 7.50 x 111km/ 10 = 832.5km or r= 832.5km, then …. where, = 832.5km = 3.14x (832.5km)2 = 3.14x 693056.25 km2 = 2, 176,196.63km2 Actual area of the country = 1,106,000km2 then, the ratio of the actual area of a country to the area of the smallest inscribing circle - A/A’= A/A’ = 1,106,000km2 /2, 176,196.63km2 = 0.5 This value is nearer to 1 suggests more compactness or approximately compact shape c, Using the Area-borderline ratio =A/B ratio it can computed as A/B ratio The larger the value or The larger the areal size per unit boundary length, the more compact the country is A/B ratio = 1,106,000km2/5260km = 210km2/1km What does this ratio/value imply? It implies that 210km2 areas of the hinterland would become free from the attack of an enemy, if 1 km borderline is safeguarded by the national army. It shows militaristic advantage implication of shapes Shapes have many implications on the administrative, defense and socio economic integration of the countries. For instance Circular or compact shape is easier for administration, defense, socioeconomic and cultural integration of the countries  Stabilization Since Ethiopia’s north-south and east- west stretches are almost equal, the country has a moderately compact shape. The compact nature of Ethiopia’s shape has advantages for the country’s socio-economic, political and security-related programs and activities.  Evaluation What are the three theoretical indicators of the compactness of an area? How the index of compactness is computed? What is the advantage of compact shape? What makes Ethiopia possess a relatively compact shape?  1.3 GEOLOGICAL HISTORY OF ETHIOPIA In the previous section 1.2 we have learnt about the location, size and shape of Ethiopia under this section we are going to learn about: – The Geological Processes -that result in the current landform of Ethiopia) – The major geological events that have happened in Ethiopia and the horn within geological eras and their respective periods and epochs – The Landforms of Ethiopia At the end of this section, you will be able to: explain the geological history of Ethiopia; distinguish the geological processes that result in the current landform of Ethiopia; and describe major landforms of Ethiopia. 1.3.1. The Geological Processes in Ethiopia Content : in this lesson we will learn about the Geological Processes in Ethiopia or about the geological events that have happened in Ethiopia with in four geological era and their respective periods and epochs At the end of this lesson, you will be able to: explain the geological history of Ethiopia identify the areas of Ethiopia in which various geological events have occurred. identify the major geologic events and the dominant relief features of Ethiopia  Brainstorming session What is geology? What do you know about the geological history of the earth and Ethiopia? What is a geological time scale? What were the major geologic events of the Precambrian era and what life form emerged? What is Geology Geology is an Earth science that studies the evolution, origin and history of the earth, the materials of which the earth is made of, and the processes acting upon them. Mostly it is concerned with  events that took place in the remote past when no one was around to witness them and  features which are far beneath the earth's surface where no one can see them. What do you know about the geological history Ethiopia? The geological history of Ethiopia is part of the geological history of the earth. The geological history of the earth is the geological processes that acted within and upon the earth for millions of years in the past. To describe the geological history of the earth, Scientists have developed a geological time scale ? What is a geological time scale?  Geological Time Scale It is refers to the classification of the entire geological history of the earth into different time segments such as eras, periods and epochs – Era- the longest time segment/divisions – Period – the further time classification of era – Epochs - the further time divisions of period and the smallest time segment in GTS.  There are four geological eras. These are … chronologically from the oldest to the recent - Precambrian - Paleozoic - Mesozoic and Cenozoic era Each era is further classified into periods, the periods into epochs, epochs into centuries, decades, years and years into months etc Each geological era is distinguished from the others based on the following three characteristics: – the relative positions of the continents; – the character of the prevailing climate; and – the predominant life forms on the earth  I. The Precambria Era It covers the geological time from 4.5 Billion to 600 Million years ago. It is the oldest and longest geological era, covering about 5/6 of the earth’s geological time. The major geological events that occurred in Ethiopia and the Horn during Precambrian era were: – Frequent orogenic movements (mountain building process due to volcanic eruptions – Intensive volcanic activities; ….– Formation of folded mountain ranges in a NNE – SSW direction – Emergence of the first forms of life (one-celled) on the earth such as Bacteria, Algae, amoeba, and jellyfish. – Formation of the oldest crystalline/ basement complex rock. It is Metamorphic rock and the foundation rocks - found beneath all other rocks – Denudation – the wearing dawn of mountains during later period of this era … Due to continuous denudation, today, the outcrops of old crystalline/ basement complex rocks or Precambrian rocks are found on the surface in a few areas of Ethiopia and the horn. Such as – Central, western and northern Eritrea. – Central and northern Tigray; – Mettekel, Assossa, Illubabor and the Abbay Gorge; – Central Sidama, southern Omo, Bale and Borena area Figure 1.3: Geological Map of Ethiopia  Stabilization The old crystalline basement rock was formed during Precambrian era It is found beneath all other rocks- But, today, the outcrops of old crystalline basement complex rocks (Metamorphic rocks) found at the surface due to continuous denudation, in a few areas of Ethiopia such as – In central and northern Tigray; – In Mettekel, Assossa, Illubabor and the Abbay Gorge; – In central Sidama, southern Omo,  Evaluation what is geological time scale and discuss its purposes. Assignment classify sample rock in your school library into igneous, metamorphic and sedimentary rocks II. The Paleozoic Era What were the major geologic events of the Paleozoic era in Ethiopia and what life form was dominant in this era?  II. The Paleozoic Era it covers the geological time from 600 million years to 250 million years ago The major geological (geomorphic) process happened In Ethiopia and the horn was denudation followed by peneplanation. The massive denudational activity resulted in the formation of inselbergs (residual features) in some parts of Ethiopia. No significant structural formation took place. It is the only era that left a gap in a rock formation in Ethiopia. invertebrates were the dominant life forms others include Reptiles, Insects, earliest land animals and seed bearing plants III. Mesozoic era What were the major geologic events of the Mesozoic era in Ethiopia? What was the dominant life forms in the Mesozoic era? The Mesozoic Era It covers the geological time from 250 to 70 millions years ago It has three distinct periods. They are – Triassic period - 250 - 180 millions – Jurassic period - 180 - 135 millions – Cretaceous period - 135 millions – 70 million It was marked by alternate slow sinking and uplifting of the landmass (Epeirogenesis) in Ethiopia and the Horn of Africa. It was an era of sedimentary rock formation in Ethiopia, because three layers of sedimentary rocks were formed on the land mass of Ethiopia. These were Adigrat sandstone- Hintalo Lime stone – Upper sandstone, from the oldest to youngest Triassic Period- 250m -180m y.a The subsidence (sinking) of landmass began in the southeastern part of Ethiopia and progressed towards the northwestern part of the country, due to internal forces. This was led to Sea transgression from Indian Ocean (SE) into the mainland of present day Somalia and southeastern parts of Ethiopia and later extended up to northwestern parts of Ethiopia, as far as central Tigray and the western slopes of the western highlands of Ethiopia As a result of sea transgression, the 1st deposition/ the oldest sedimentary rock known as Adigrat sandstone was formed. Because of the direction of the transgression and deposition, Adigrat sandstone is the oldest and thickest in the southeast and progressively decreases in age and thickness to the northwest.  Jurassic Period – 180m to 135m y.a As the sea water transgression continued towards the NW and as water stayed for long period of time and the sea depth increases, marine life began to appear in the water. From the remains and dead parts of these marine life, another second layer of sedimentary rock known as Hintalo lime stone was formed Because of the direction of the transgression and deposition, Hintalo limestone also is younger in the northwest and older in the southeast. Cretaceous Period – 135 to 70 m.y.a The rising/uplifting of the landmass began in NW part of Ethiopia Sea regression (the sea water started to retreat) towards the southeast) Formation of The third layer of sedimentary rock known as Upper Sandstone Upper Sandstone is the youngest sedimentary rock and therefore overlies the rest. Because of the direction of the regression and deposition, Upper Sandstone is the youngest and thinnest in the southeast, and it is the oldest and thickest in the northwest.  Note Sedimentary rocks of Mesozoic Era formed on the land mass of Ethiopia later buried by overlying Cenozoic igneous rocks. However, these rocks have been exposed at the surface in some areas of Ethiopia, mostly in the : Southeastern lowlands of Ethiopia, Central Tigray, and Abbay and Wabishebelle gorges. Sedimentary rocks are located in nearly all the southeastern parts of Ethiopia, as well as in the Somali lowlands -Mesozoic sedimentary rocks cover 25% of the country. -They have the greatest potential for oil and gas deposits. Figure 1.3: Geological Map of Ethiopia Life forms of Mesozoic era This era was also known for the predominance of dinosaurs at the end of this era, two other significant biological events occurred: – one was the disappearing of the dinosaurs, and – the other was the emerging of birds and flowering plants. IV. The Cenozoic Era Enumerate the major geological events that have happened in Ethiopia and in the Horn during the Cenozoic era? Do you know the era in which the Great East African rift valley was formed?  4. The Cenozoic Era It covers the time from 70 million to present It is the most recent geological era. It is the era in which very significant structural landforms, climatic and biological events have occurred in Ethiopia. Thus, its geologic events have greatly resulted in the development of very recent landforms in the Horn of Africa in general and Ethiopia in particular. It has two periods namely, Tertiary and Quaternary period  What geological events happened during: a, Tertiary period -70 million - 2 million years ago The uplifting that began in the Cretaceous Period continued and reached its maximum height and formed huge blocks of dome over the greater part of Ethiopia and the Horn region. Then through time, fracturing and faulting of the landmass began and followed by the pouring out of extensive basaltic lava flow known as the Trappean lava series. The lava has resulted in the formation of: – the Northwestern Highlands, – the Southeastern Highlands, and – the Somali plateaus.  The great cracks opened in the crust. continued and resulted in the formation of Great East African Rift Valley System The Great East African Rift Valley System is extends from Palestine and Jordan in the north (Middle East) to Malawi Mozambique in the south, for a distance of about 7,200 kilometers. of which, 5,600 kilometers is in Africa, and 1,700 kilometers in Eritrea and Ethiopia The Ethiopian Rift Valley System is part of it The period was also characterized by the rise of mammals b, Quaternary period – 2million to present It is known for its recent volcanic activities - quaternary lava The following Significant structural landforms were formed in Ethiopia and the Horn  the Afar Horst that extends from Afar into Djibouti,  the active volcano of Ertalle in Afar,  the dormant volcanic mountain of Fentalle  the extensive lava field/sheets of Metahara,  thermal springs and fumeroles of the rift valley, … Climate change and Quaternary deposition – Climate change brought heavy rain called (pluvial rain) with cooler and wet periods in Africa. – The heavy rain eroded the Ethiopian plateau and the eroded material were deposited in the Rift Valley lakes. – Lastly, the wet climate was replaced by dry climate & evaporation that led to extinct of great lakes and life from Rift Valley Quaternary period of Cenozoic era is assumed to be the period in which modern man evolved Figure 1.3: Geological Map of Ethiopia Stabilization Major geological events in Ethiopia and the Horn during: Precambrian era- was the formation crystalline basement – metamorphic rocks Paleozoic era was denudation and peneplanation – no significant rock formation Mesozoic era were the alternative sinking and uplifting of the land mass and formation three sedimentary rocks. These are Adigrat sandstone, Hintalo limestone, and Upper Sandstone During Cenozoic eras there were the formation of Ethiopian highlands, Ethiopian RV and quaternary deposition at lowlands and RV areas The landforms of Ethiopia are largely the result of the Cenozoic era. Metamorphic rocks are found in- Abay Gorge, Assossa, Western and Central Eritrea and many other locations; Sedimentary rocks are located in nearly all the southeastern parts of Ethiopia, as well as in the Somali lowlands and Quaternary lava deposits- can be found in the Afar region and Djibouti. Evaluation When was the present relief of Ethiopia formed? how and when was Ethiopian rift valley system formed? Which geological era is significant regarding the formation of the various landforms in Ethiopia? 1.3.2 Landforms of Ethiopia – In this lesson we are going to learn about major landforms of Ethiopia. At the end of this lesson, you will be able to: ➡ describe major landforms of Ethiopia.  Brainstorming session What do you know about the landforms of Ethiopia? Can you tell some of the landforms that exist in your area? Do you know how the mountains and plateaus of Ethiopia were created? Where do we have the world’s largest rift valley? Introduction The landforms of Ethiopia are the results of the geological processes and changes that have happened since the formation of the region. The majority of the present landforms of the Ethiopia are results of the geological events of the tertiary and quaternary periods of Cenozoic era The existing landforms of Ethiopia. are created by a combination of two forces. i.e the endogenic and exogenic forces – The endogenic forces are originate from inside the earth. These are faulting, folding and volcanic activities – The exogenic forces are originate at the surface (denudation and penepalantion)- weathering and erosion Many landforms of the Ethiopia are largely the results of the tectonic processes and volcanic activities of Cenozoic era. Landforms of Ethiopia are characterized by great diversity of highlands, plateaus, ambas, and rugged mountains, deep river gorges and lowlands.  Start up question What are the three major landform features of Ethiopia? What are the three physiographic division/regions of Ethiopian Topography or relief features of Ethiopia Enumerate the Western highlands and lowlands of Ethiopia?  They can be broadly categorized into three groups as highlands, lowlands, and the rift valley. The highlands of the country are divided into two diagonally by Ethiopian RV. They are the north western highlands of Ethiopia and the south eastern highlands of Ethiopia. The lowlands of the country comprise the western lowlands and The southeastern lowlands. The Ethiopian Rift Valley System- it divided the Ethiopian highland in to two. It has three parts – The Afar triangle stretches from the Afar Depression in the north, – The main Ethiopian Rift Valley (the Lakes’ region) – The Chew Behair up to Lake Turkena  Altitude varies from ….about 116 meters below mean sea level at the Dallol depression (Kobar sink) to 4620 m above mean sea level (a.m.s.l.) at Ras Dashen in the Semein mountain system. If 1000 meters is chosen as a demarcating contour line between highlands and lowlands Highlands of Ethiopia – Account for about 56% of Ethiopia’s landforms – has given Ethiopia the name “Roof of Eastern Africa.” – Make Ethiopia the only country in the region with a high proportion of elevated surface. – bisected diagonally by the Rift Valley Figure 1.4. Topography of Ethiopia The relief of Ethiopia In general, the relief of Ethiopia can be divided into three main physiographic divisions, based on the geological and structural features. They are – The Western Highlands and Associated Lowlands = 44% (HLs accounts 76.3% and the LLs 23.7% – The Southeastern Highlands and Associated Lowlands = 38% – The Rift Valley system = 18% Figure 1.5. Ethiopian’ Main Topographic Regions I. The western Highlands and Associated Lowlands A, The western Highlands – The Plateau of Tigray – The North Central Massif – The Plateau of Shewa – The Southwestern Highlands B, The Western Lowlands – The Tekezze and Angereb Lowlands, – the Abbay Dinder Lowlands, – the Baro-Akobo Lowlands, and – the Omo-Gibe Lowlands A, The Western Highlands They stretch from Tigray in the north to the highlands of Gamo and Goffa in southwest. They are separated from the southeastern highlands by the Rift Valley. They are the biggest physiographic region. They make up 44% of the area of the country They are the source of famous rivers like Abbay, Baro and Tekezze, which influence Ethiopia’s geopolitics role in north eastern Africa and the Middle East as these rivers trans boundary. They are further sub-divided into four groups of highlands. These are ( Based on the internal altitudinal variability) – The Plateau of Tigray – The North Central Massif – The Plateau of Shewa – The Southwestern Highlands  Evaluation What are the three major landform features of Ethiopia? What are the three physiographic division/regions of Ethiopian Topography or relief features of Ethiopia Enumerate the Western highlands and lowlands of Ethiopia?  2nd period The Western Highlands and lowlands  Start up questions Have you ever had the opportunity to travel from your locality to nearby plateau? If yes, what do you recognize all the way through until you reach any gorge? 1. List the four sub-divisions of western highlands and lowlands and discuss on their feature 2. List three well-known mountains that are situated on the plateau of Tigray. 3. List well-known mountains that are situated on the NCM. 4. What makes the Northern central Massif distinct from the Massif of central Ethiopia? Why are northern mountains highly rugged? 5. Which regional zones are found in the southwestern highlands of the Horn?  a, The Tigrean plateau It is the most northerly group of plateau of western HLs It bounded in the north by the Mereb River and in the south by the Tekezze river. It is drained by Mereb and the tributaries of the Tekezze. It is an area composed largely of sandstones and limestones, as the overlying basalt has been eroded.  …… It has been exposed to severe erosion due to long periods of human inhabitation. It has poor and thin soil. It has very high mountains peaks with elevations over 3000m a.s.l. Of these mountains, Three known mountain peaks are include – Mount Tsibet – 3988 m – Mount Ambalage – 3291 m – Mount Assimba – 3248 m Tsi Am Asi 3988m 3291m 3248m  b. The North Central Massif They are found between the Tekezze Gorge in the North and the Abbay Gorge in the south. Contain the highlands of Gondar, Gojjam and Wollo. Abbay and Tekezze rivers along with their tributaries have formed a number of gorges and steep sided river valleys. The most rugged and dissected plateaus of Ethiopia. They are capped by basalts of the tertiary period and surrounded by deep gorges formed by the Abay and Tekeze Within each of these dissected plateaus there are small arable lands known as ambas. The ambas are isolated from one another by gorges.  The North Central Massif They have two major group of mountain systems. – The western Massif (group of mountains ) – make up the Massif of South Gondar (Semein mountains) in the north and Gojjam Massif to the south – The eastern Massif (group of mountains) - make up the Lasta and Wollo Massif – The western group of mountains separated from the eastern group of mountains by impenetrable and deep gorges and connected by Yeju-Wadla Delanta land bridge (ridge) at one point.  The Gojjam Massif It is the most extended tableland It is comparatively less dissected. It is formed on the core of the Amedamit- Choke mountains – source of Abay river It is curved by the Abbay river that separated it from the Shewa plateau in the south and the Amhara Saynt Massif in the northeast. The North-Central Massif are known Known mountain peaks with an elevation more than 4000 m in NCM are Mount Ras Dashen – 4620 m a.m.s.l., Mount Legeda – 4532 m a.m.s.l., Mount Analu – 4480 m a.m.s.l., Mount Tefaw Lezer – 4456 m a.m.s.l., Mount Kolo – 4300 m a.m.s.l., Mount Guna – 4231 m a.m.s.l., Mount Abuna Yoseph – 4190 m a.m.s.l., and Mount Hey – 4154 m a.m.s.l.  C. The Plateau of Shewa (Central Plateau) It is the smallest sub-division of the western highlands.  It has the largest proportion of elevated ground (Nearly ¾ (75%) of its area has an altitude of more than 2,000 meters –  It is dome shaped plateau that serves as a water divide or water shade for three river basins (Abay, Omo/Gibe , and Awash River basins. It is drained by the tributaries of the Abbay River in the west and the Awash River in the east. It extends westwards into western Wollega through Horo Guduru and forms a crescent shape which causes the Abbay to swerve and drain northwards.  The Shewan plateau has…. relatively extensive flat-topped uplands, giving it the appearance of a true plateau The Shewan plateau is separated from: – the plateau of Gojjam by the Abbay gorge in the north; – the southeastern highlands by the Awash River and the Rift Valley, and – the Highlands of Kafa by the Gibe River. Its high mountains are found on its northeastern and south eastern margins of the plateau. These are: – Mount Abbuye Meda – 4000 m a.m.s.l., – Mount Guraghe – 3721 m a.m.s.l.  d, The southwestern highlands region It lies south of the Abbay trough it is greatly eroded region, due to torrential rain that pours down in the area for almost all of the year. It is the wettest region of the country with average annual rainfall of above 1500 mm. It include the highland of – Wollega, – Illubabor, – Jimma, – Kafa and – Gamo and Goffa. The southwestern highlands region is drained by : the Dabus and Didesa tributaries of the Abbay River; in north Omo-Gibe River, which ends in Lake Turkana; in South The headstreams of the Baro- Akobo River in West The Gojeb- River, the tributary of Ghibe, in Jimma Zone and Yem Special Woreda) in East  …. The general elevation of SW highlands region is relatively low when compared to that of the Northern and Eastern Highlands. Only a few areas are above 2500 meters. The highest points in the region are the: – Gamo-Konso Highlands, – Maji-Korma Highlands, – Dawuro-Konta Highlands, – Tullu Wallel, and – Benishangul mountain Mount Gughe (found in the Gamo plateau) has the highest altitude: 4200 m  …. Southwestern highlands are well-known for the production of – Coffee – Inset – Spice – Timbering – Rubber tree – Cattle – Honey – Maize and – high percentage of forest cover.  B. The Western Lowlands They are the western foothills and border plains that extend from Western Tigray in the north to southern Gamo-Gofa in the South, bordering the Sudan and South Sudan with a general elevation of 500-1000m They are sub-divided into 4 groups – the Tekezze and Angereb Lowlands, – the Abbay Dinder Lowlands, – the Baro-Akobo Lowlands, and – the Omo-Gibe Lowlands With the exception of the Baro lowland, the region is generally characterized by arid or semi-arid conditions I. … The Baro-Akobo lowland is the wettest lowland compared to other lowlands of this physiographic division. That is why the rivers draining the region (particularly the Baro river) have almost a regular flow of water for much of the year II. The Tekezze and Angereb Lowland - the most northerly lowlands of western LLs, drained by Tekezze and Angereb. III. The Abbay Dinder Lowland- extend from south of Metema town up to the southern part of the Abbay River. IV. Ghibe/Omo lowland includes the lower Omo Valley and the northern section of the Turkana basin, It classified in the Western lowlands from its geographical location. But structurally it belongs to the Rift Valley. In the Western lowlands Because of climatic hardship in most parts of these lowlands, the communities practice pastoralist and semi-pastoralist ways of life. there are small but important/notable towns- simply border towns and frontier ports, that serve as business centers for the communities living along the Ethio- Sudanese border. These are Humera, Metema, Omedla, Kurmuk, Gambella etc,  3rd period Can you propose what feature separates these highlands from the northwestern highlands? Which highlands are said to be the components of southeastern highlands of Ethiopia? II. The Southeastern Highlands and Associated Lowlands (physiographic region) = 38% It is the 2nd largest physiographic region It is found to the southeast of the rift valley. It is further divided into highland and lowland units – Southeastern HLs include a) the Hararghe plateaus, b) the Arsi plateau, c) the Bale Massif, and d) the Sidama highlands – SE LLs include Ogaden Elkere, Borena, Wabeshabelle plains A, The Southeastern Highlands Their formation is similar to that of the North and Southwestern Highlands and they are capped by basaltic rock. They are the main sources of the Wabe Shebelle and Genale rivers. They are bounded by: the fault line of the Rift Valley in in the west; the Ogaden Lowlands in the east, ; and the Elkerie and Borena Lowlands in the south  a. The Hararghe Plateaus It rises sharply from the fault line of the Rift Valley and extends gently to the east up to Jigjiga. After Jigjiga, a fall in elevation takes place, giving way to the Ogaden Lowlands. It is drained by the left-bank tributaries of the Wabe Shebelle River. The basaltic rocks have been worn away, exposing limestones and earlier sedimentary rocks. It is significant producers of coffee, chat, sorghum and millet. Its prominent mountain peaks are: Mount Gara Muletta (3381 m), and Mount Jebel Tita (3122 m).  b. The Arsi Plateau It consists of the Gugu and Chillalo Massif. It is an extending rolling plateau It is a very suitable plateau for farming. It is known for its production of wheat The highest points on the Arsi plateau are: – Mount Kaka (4180 m) – Mount Bada (4139 m), and  c. The Bale Massif - the Bale Mountains It is separated from Arsi Plateau by the headstreams of the Wabe Shebelle, popularly known as the Wabe River. It consists of a flat basaltic plateaus in the north part and huge mountains in its southern part The highest points on the Bale Mountains are: – Mount Tulu Dimtu (4377 m), and – Mount Batu (4307 m) It is known for its production of  d. The Sidama Highland/plateau It separated from the Bale Massif/Highlands by the Genale river valley. It constitutes the southwest extension of the southeastern highlands. It slopes away gently to the south and southeast, and It is drained by the Genale and its tributaries. (Tributaries of Ghanale Welmel, Dawa,  B. The Southeastern Lowlands They extend from the foot hills of the southeastern highlands along the Ethio-Somalian and Ethio-Kenyan borders. They consist of: the Ogaden plains, the Elkeri plains, the Borena plains, and the wabe shebelle and Genale plains Most of these lowlands are covered by sandstones and recent marine deposits.  The Southeastern Lowlands They are highly extensive lowlands. They are characterized by extreme climatic condition with low annual rainfall-often below 500 mm and high temperature The people practice a pastoralist way of life because of this harsh climate Highlands of Ethiopia  III. The Rift Valley Start up questions What is the difference between a river valley system and a rift valley system? Can you give examples? Why RV is the most unstable part of the country Discuss the characteristics of the Rift Valley physiographic regions of Ethiopia What are subdivisions that exist in the Rift Valley physiographic region of Ethiopia?  The Ethiopian Rift Valley System It is a narrow strip of land that stretches from the Afar Depression in the north, through the Rift Valley Lakes’ region to Chew Behair in the south and extends up to Lake Turkena. It runs diagonally from northeast to southwest by dividing Ethiopia Highlands into two parts It is part of the Great East African Rift Valley, that extends from the Jordan River valley in the north, through the Red Sea, and then across East and Central Africa to Mozambique in the Figure 1.6. The Rift Valley System of Ethiopia and the Horn  …. The rift valley was formed at the end of the Tertiary Period as a result of tectonic epeirogenic activity. Geologically, It is the most unstable part of the country. The presence of active volcanoes like Erta’ale cinder cones minor faulting hot springs fumaroles and geysers could be good evidence for the unstable nature of the region geologically.  …. It comprises 18% of the country’s total area. It is subdivided into three main parts: a) The Afar Triangle (northern part), b) The Main Ethiopian Rift or the Lakes’ Region (central part), and c) The Chew-Bahir Rift (southern part)  a) The Afar Triangle (Northern Part) It is the largest and widest part of the rift valley extending 200-300kms width. Its altitude is generally low, ranging from 116m bsl at the Kobar Sink to about 900m asl at Awash town. Much of the area here lies below sea level. It is characterized by – Faulted depressions (the Dallol Depression) and grabens (troughs), – Cinder cones and Volcanic mountains – Extensive salt plains and lakes (for instances, Lake Assale and Lake Afrera in Afar). – Active volcano such as Erta’ale  …. The Afar Triangle is bounded by parallel fault lines on the east and west. Its floor is made up of: – Grabens such as the Tendaho Graben, – Volcanic ash and lava deposits, – Lacustrine and fluvial deposits, and – Volcanic mountains such as Mount Fentalle. It has special characteristics that do not exist in other regions of Ethiopia. It consists of Fossil rich sediments, and Rich archeological sites – shows it was the home of the ancient ancestors of primates and hominids. b) The Main Ethiopian Rift or the Lakes Region It is the central subdivision of the Ethiopian Rift It covers the area from the lower Awash basin up to Lake Chamo. It is the most elevated and narrowest part of the Ethiopian Rift Valley. It is also the wettest, most densely vegetated, and densely populated part of the RV Unlike others, sedentary farming is practiced It also includes numerous lakes of enormous economic and aesthetic value. Zway, Langano, Hawasa, Abijata, shalla, Abaya and Chamo lakes  c) The Chew-Bahir Rift part It is the southern subdivision of the Ethiopian Rift It is also known as the Omo-Gibe trough. It is the smallest section of the Ethiopian RV part It separated from the Lakes’ Region by Konso Highlands and its surroundings in north It consists of an extensive shallow marshy area covered by tall grasses into which the Sagan and Woito streams end. It is split into the Ganjuli and the Galena Valleys by the Amaro mountain range around Arba Minch area. At large, it is occupied by a pastoralist population.  Unit summary Ethiopia is located in Eastern Africa within the 3o N-15o N latitudes and 33o E-48o E longitudes. Regarding shape, Ethiopia has more or less compact shape. In terms of size, Ethiopia is the tenth largest country in Africa. It has an area of 1,106,000 square kilometers. Because of its large size, Ethiopia enjoys a diverse climate, a great variety of fauna and flora, diversified ethnic groups and a large potential of arable land as well.  …. The geological time scale measures time on a scale involving four major geological eras. The geological structure of Ethiopia is the result of the geological events that occurred during these eras. For example, Crystalline basement complex rocks were formed during the Precambrian era; Denudation and Peneplanation took place during the Paleozoic era; land mass sinking and up-lifting were dominant during the Mesozoic era; formation of Ethiopian Rift Valley System during Cenozoic era respectively.  …. The landforms of Ethiopia are largely the results of the Cenozoic era tectonic and volcanic activities. Consequently, Ethiopia has rugged mountains, plateaus, ambas, river gorges, a rift valley and lowlands. The altitudinal variation in Ethiopia ranges from the highest peak, Ras Dashen (4620m asl) to the lowest point, Kobar Sink (116m bsl)  Home work REVIEW EXERCISE Group 1 MC 1-3 , Fill BS 1, Give Short An 1-3 Group 2 MC 4-6, Fill BS 2, Give Short An 4-6 Group 3 MC 7-9, Fill BS 3, Give Short An 7-9