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This is the complete lecture note for GEO 101 Introduction to Physical Geography. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Course Code: GEO 101 Course Title: Introduction to Physical Geography Course Units: 2 Units Series 1: Earth’s Physical Systems: Lithosphere, Atmosphere, and Hydrosphere Part 1 Composition and Structure of the Lithosphere • Definition and components of the lithosphere • Layers of the earth’s crust • Significance of the lithosphere in physical geography Part 2 Composition and Structure of the Atmosphere • Definition and components of the atmosphere • Vertical structure of the atmosphere • Functions of the atmosphere in regulating climate and weather Part 3 Composition and Structure of the Hydrosphere • Definition and components of the hydrosphere • Distribution of water bodies on earth • Role of the hydrosphere in the cycling of matter and energy Part 4 Interactions among the Lithosphere, Atmosphere, and Hydrosphere • Earth system linkages and feedbacks • Examples of interactions (e.g., erosion, rainfall, ocean currents) • Importance of integrated study of earth’s physical systems Introduction The earth is our shared home, yet many of its physical systems remain unseen and often taken for granted. Beneath our feet lies the solid lithosphere, above us stretches the atmosphere, and surrounding us flows the hydrosphere. Together, these systems form the foundation upon which life depends, influencing the landscapes we inhabit, the air we breathe, and the water that sustains us. Understanding their composition and structure is
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS therefore essential for appreciating how the physical environment operates and for recognising the interconnectedness of natural processes. The aim of this Series is to equip you with the knowledge needed to describe and explain the composition and structure of the lithosphere, atmosphere, and hydrosphere, as well as to analyse how these systems interact to shape the earth’s environment. We shall commence this Series by examining the composition and structure of the lithosphere, focusing on the layers of the earth’s crust and their significance. Next, we will explore the atmosphere, considering its vertical structure and its role in regulating climate and weather. Following that, we will turn to the hydrosphere, looking at the distribution of water bodies and their importance in the cycling of matter and energy. Finally, we will wrap up by studying the interactions among these three systems, highlighting how they work together to maintain balance in the earth’s environment. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 2.1 define the lithosphere and describe its composition and structure, • SLO 2.2 explain the layers of the earth’s crust and analyse their significance in physical geography, • SLO 2.3 define the atmosphere and describe its vertical structure, • SLO 2.4 explain the functions of the atmosphere in regulating climate and weather, • SLO 2.5 define the hydrosphere and describe its major components, • SLO 2.6 analyse the distribution of water bodies and evaluate their role in the cycling of matter and energy, • SLO 2.7 explain the interactions among the lithosphere, atmosphere, and hydrosphere, and • SLO 2.8 evaluate the importance of studying earth’s physical systems as an integrated whole. 1.1 Composition And Structure Of The Lithosphere 1.1.1 Definition and components of the lithosphere The lithosphere is the rigid outer shell of the earth, consisting of the crust and the uppermost part of the mantle. It is broken into large sections called tectonic plates, which move slowly over the softer layer beneath. These plates are responsible for shaping the earth’s surface through processes such as mountain building, earthquakes, and volcanic activity.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: The lithosphere is made up of the earth’s ______ and the uppermost mantle. Figure 1.1: Structure of the lithosphere 1.1.2 Layers of the earth’s crust The crust is the outermost layer of the lithosphere. It is divided into two types: the continental crust, which is thicker and less dense, and the oceanic crust, which is thinner and denser. The continental crust is mainly composed of granite, while the oceanic crust is largely basaltic. These differences explain why continents stand higher than ocean basins. Fill in the blank: The continental crust is mainly composed of ______, while the oceanic crust is largely basaltic. Feature Continental Crust Oceanic Crust Average Thickness 30 – 50 km (can reach up to 70–100 km under mountains) 5 – 10 km (relatively uniform) Density ~2.7 $g/cm^3$ (lower density; "floats" higher) ~3.0 $g/cm^3$ (higher density; sits lower in the mantle)
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Feature Continental Crust Oceanic Crust Primary Composition Granitic (Felsic); rich in silica and aluminum (Sial) Basaltic (Mafic); rich in iron and magnesium (Sima) Common Rock Types Granite, Gneiss, Sedimentary rocks Basalt, Gabbro Average Age Very old (up to 4 billion years) Relatively young (typically <200 million years) Table 1.1 Comparison of continental and oceanic crust 1.1.3 Significance of the lithosphere in physical geography The lithosphere plays a crucial role in shaping the earth’s physical environment. It provides the foundation for landforms, influences soil formation, and supports ecosystems. Human activities such as mining, agriculture, and construction also depend on lithospheric resources. Studying the lithosphere helps us to explain natural hazards like earthquakes and volcanic eruptions, and to evaluate how these processes affect human societies. Fill in the blank: The lithosphere is significant because it provides the foundation for ______ and supports ecosystems. Box 1.1 Key functions of the lithosphere
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS • Provides the base for landforms • Supports ecosystems and human activities • Influences soil formation • Source of minerals and energy resources Pilot questions 1.1 1. Which two layers make up the lithosphere? 2. What is the main difference between continental crust and oceanic crust? 3. Name one rock type that dominates the continental crust. 4. Why is the lithosphere important in physical geography? 5. What natural hazards are associated with lithospheric processes? 1.2 Composition And Structure Of The Atmosphere 1.2.1 Definition and components of the atmosphere The atmosphere is the envelope of gases surrounding the earth, held in place by gravity. It is composed mainly of nitrogen, which makes up about 78 per cent, and oxygen, which accounts for about 21 per cent. Other gases such as carbon dioxide, argon, and trace amounts of water vapour are also present. These gases are essential for sustaining life, regulating temperature, and protecting the earth from harmful solar radiation. Fill in the blank: The atmosphere is held in place around the earth by ______.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.2: Composition of the atmosphere 1.2.2 Vertical structure of the atmosphere The atmosphere is divided into layers based on temperature changes with altitude. These layers include the troposphere, where weather occurs, the stratosphere, which contains the ozone layer, the mesosphere, the thermosphere, and the exosphere, which gradually merges into outer space. Each layer has distinct characteristics and functions. For example, the troposphere extends up to about 12 kilometres and is where clouds form, while the stratosphere protects life by absorbing ultraviolet radiation. Fill in the blank: The layer of the atmosphere where weather occurs is called the ______. Figure 1.3: Vertical structure of the atmosphere
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 1.2.3 Functions of the atmosphere in regulating climate and weather The atmosphere plays a vital role in controlling the earth’s climate and weather. It regulates temperature by trapping heat through the greenhouse effect, distributes energy through wind and circulation systems, and provides oxygen for respiration. The atmosphere also shields the earth from harmful solar radiation and helps maintain the water cycle by transporting moisture. Without these functions, life on earth would not be possible. Fill in the blank: The atmosphere regulates temperature by trapping heat through the ______ effect. Box 1.2 Key functions of the atmosphere • Regulates temperature through the greenhouse effect • Distributes energy via circulation systems • Provides oxygen for respiration • Shields the earth from harmful radiation • Maintains the water cycle Pilot questions 1.2 1. What are the two most abundant gases in the atmosphere? 2. Which atmospheric layer contains the ozone layer? 3. Name the layer of the atmosphere where weather occurs. 4. How does the atmosphere regulate temperature? 5. Why is the atmosphere essential for sustaining life?
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