How are rivers and lakes formed?

Erosion from flowing water and deposition of sediment

How rivers and Lakes are formed

Lesson 1: Continental Drift Theory and the Evidences that support the Theory Continental drift describes one of the earliest ways geologists thought continents moved over time. Today, the theory of continental drift has been replaced by the science of plate tectonics. The theory of continental drift is most associated with the scientist Alfred Wegener. In the early 20th century, Wegener published a paper explaining his theory that the continental landmasses were “drifting” across the Earth, sometimes plowing through oceans and into each other. He called this movement continental drift. Pangaea Wegener was convinced that all of Earth’s continents were once part of an enormous, single landmass called Pangaea. Wegener, trained as an astronomer, used biology, botany, and geology describe Pangaea and continental drift. For example, fossils of the ancient reptile mesosaurus are only found in southern Africa and South America. Mesosaurus, a freshwater reptile only one meter (3.3 feet) long, could not have swum the Atlantic Ocean. The presence of mesosaurus suggests a single habitat with many lakes and rivers. Wegener also studied plant fossils from the frigid Arctic Archipelago of Svalbard, Norway. These plants were not the hardy specimens adapted to survive in the Arctic climate. These fossils were of tropical plants, which are adapted to a much warmer, more humid environment. The presence of these fossils suggests Svalbard once had a tropical climate. Finally, Wegener studied the stratigraphy of different rocks and mountain ranges. The east coast of South America and the west coast of Africa seem to fit together like pieces of a jigsaw puzzle, and Wegener discovered their rock layers “fit” just as clearly. South America and Africa were not the only continents with similar geology. Wegener discovered that the Appalachian Mountains of the eastern United States, for instance, were geologically related to the Caledonian Mountains of Scotland. Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up. Over millions of years, Pangaea separated into pieces that moved away from one another. These pieces slowly assumed their positions as the continent we recognize today. Today, scientists think that several supercontinents like Pangaea have formed and broken up over the course of the Earth’s lifespan. These include Pannotia, which formed about 600 million years ago, and Rodinia, which existed more than a billion years ago. Tectonic Activity Scientists did not accept Wegener’s theory of continental drift. One of the elements lacking in the theory was the mechanism for how it works—why did the continents drift and what patterns did they follow? Wegener suggested that perhaps the rotation of the Earth caused the continents to shift towards and apart from each other. (It doesn't.) Today, we know that the continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics. The continents are still moving today. Some of the most dynamic sites of tectonic activity are seafloor spreading zones and giant rift valleys. In the process of seafloor spreading, molten rock rises from within the Earth and adds new seafloor (oceanic crust) to the edges of the old. Seafloor spreading is most dynamic along giant underwater mountain ranges known as mid-ocean ridges. As the seafloor grows wider, the continents on opposite sides of the ridge move away from each other. The North American and Eurasian tectonic plates, for example, are separated by the Mid-Atlantic Ridge. The two continents are moving away from each other at the rate of about 2.5 centimeters (1 inch) per year. Rift valleys are sites where a continental landmass is ripping itself apart. Africa, for example, will eventually split along the Great Rift Valley system. What is now a single continent will emerge as two—one on the African plate and the other on the smaller Somali plate. The new Somali continent will be mostly oceanic, with the Horn of Africa and Madagascar its largest landmasses. The processes of seafloor spreading, rift valley formation, and subduction (where heavier tectonic plates sink beneath lighter ones) were not well-established until the 1960s. These processes were the main geologic forces behind what Wegener recognized as continental drift.

Think about the geography and location of the city or town you live in. Are there bodies of water like rivers and lakes or a coast nearby? Perhaps you live in a place with vast open fields suitable for farming or raising livestock. The natural environment is important when understanding how cities and towns developed. The earliest North American colonies depended on their natural environment. The type of soil, climate, length of seasons, and proximity to bodies of water all played a role in how each colony prospered. By the 1700’s, the American colonies grew into three distinct regions. The New England, Middle, and Southern regions each had different geographical and cultural characteristics that determined the development of their economy, society, and relationships to each other. The New England Colonies included Connecticut, Rhode Island, Massachusetts, and New Hampshire. The geography of this region featured dense forests and hills. Combined with the hard rocky land, cold climate and long winters, New England was a poor area for large farming operations. However, many colonists known as "yeoman farmers" had small family-owned farms that grew a variety of crops. Many other colonists relied on fishing and whaling off the New England coast. Others settled in small towns and became craftsmen or merchants. The forests provided excellent lumber for building boats and homes for the growing population. Many of the settlers to the New England Colonies were Puritans, hardworking, and very religious. Close families and strong communities were very important to them. The Middle Colonies included Pennsylvania, Delaware, New York, and New Jersey. The geography of this region featured a warmer climate with fertile soil, flat land, easily navigable rivers, and wide valleys making it perfect for farming and growing crops. Wealthy farmers grew cash crops and raised livestock. Mining and trading were also important aspects of the economy here. Over time, cities grew, and urban merchants sold and traded goods with people throughout the other colonies. Compared to other regions, the people of the middle colonies supported religious freedom and tolerance and had a diverse population with settlers arriving from many areas in Europe. The Southern Colonies included the first English colony of Virginia, and grew to include Maryland, North Carolina, South Carolina, and Georgia. The geography included rich, fertile soil with broad coastal plains that made it possible for large plantations to grow tobacco, rice, and indigo. Most of these plantations featured a labor force of enslaved Black people. These enslaved men, women, and children had few, if any, rights and often saw their families torn apart at the whim of the plantation owner. Enslaved children were even put to work as young as age three, weeding fields, carrying drinking water, or helping in the home. Smaller farms owned by subsistence farmers also existed across the Southern Colonies. Often, the people working these would grow crops for their families with little left over to sell or trade. Indentured servants also arrived in the South who would work for 5-7 years in exchange for their passage to North America. The Church of England (also known as the Anglican Church) was the dominant religion in the region. Most settlers to the South did not come for religious freedom like they did in the northern colonies. Therefore, they often maintained their allegiance to the established Church of England.

A solution is a mixture in which one or more substances are uniformly distributed in another substance. Solutions can be mixtures of liquids, solids, or gases. For example, plasma, the liquid part of blood, is a very complex solution. It is composed of many types of ions and large molecules, as well as gases, that are dissolved in water. A solute (SAHL-YOOT) is a substance dissolved in the solvent. The particles that compose a solute may be ions, atoms, or molecules. The solvent is the substance in which the solute is dissolved. For example, when sugar, a solute, and water, a solvent, are mixed, a solution of sugar water results. Though the sugar dissolves in the water, neither the sugar molecules nor the water molecules are altered chemically. If the water is boiled away, the sugar molecules remain and are unchanged. Solutions can be composed of various proportions of a given solute in a given solvent. Thus, solutions can vary in concentra- tion. The concentration of a solution is the amount of solute dis- solved in a fixed amount of the solution. For example, a 2 percent saltwater solution contains 2 g of salt dissolved in enough water to make 100 mL of solution. The more solute dissolved, the greater is the concentration of the solution. A saturated solution is one in which no more solute can dissolve. Aqueous (AY-kwee-uhs) solutions—solutions in which water is the solvent—are universally important to living things. Marine microorganisms spend their lives immersed in the sea, an aqueous solution. Most nutrients that plants need are in aqueous solutions in moist soil. Body cells exist in an aqueous solution of intercellu- lar fluid and are themselves filled with fluid; in fact, most chemical reactions that occur in the body occur in aqueous solutions. Copyright © by Holt, Rinehart and Winston. All rights reserved. Liquid water Solid water Ice (solid water) is less dense than liquid water because of the structure of ice crystals. The water molecules in ice are bonded to each other in a way that creates large amounts of open space between the molecules, relative to liquid water. FIGURE 2-12 solvent from the Latin solvere, meaning “to loosen” Word Roots and Origins CHEMISTRY OF LIFE 43 ACIDS AND BASES One of the most important aspects of a living system is the degree of its acidity or alkalinity. What do we mean when we use the terms acid and base? Ionization of Water As water molecules move about, they bump into one another. Some of these collisions are strong enough to result in a chemical change: one water molecule loses a proton (a hydrogen nucleus), and the other gains this proton. This reaction really occurs in two steps. First, one molecule of water pulls apart another water molecule, or dissociates, into two ions of opposite charge: H2O ∏ H OH The OH ion is known as the hydroxide ion. The free H ion can react with another water molecule, as shown in the equation below. H H2O ∏ H3O The H3O ion is known as the hydronium ion. Acidity or alkalin- ity is a measure of the relative amounts of hydronium ions and hydroxide ions dissolved in a solution. If the number of hydronium ions in a solution equals the number of hydroxide ions, the solution is said to be neutral. Pure water contains equal numbers of hydro- nium ions and hydroxide ions and is therefore a neutral solution. Acids If the number of hydronium ions in a solution is greater than the number of hydroxide ions, the solution is an acid. For example, when hydrogen chloride gas, HCl, is dissolved in water, its mol- ecules dissociate to form hydrogen ions, H, and chloride ions, Cl, as is shown in the equation below. HCl ∏ H Cl These free hydrogen ions combine with water molecules to form hydronium ions, H3O. This aqueous solution contains many more hydronium ions than it does hydroxide ions, making it an acidic solution. Acids tend to have a sour taste; how- ever, never taste a substance to test it for acidity. In concentrated forms, they are highly corrosive to some materials, as you can see in Figure 2-13. Bases If sodium hydroxide, NaOH, a solid, is dissolved in water, it dissociates to form sodium ions, Na, and hydroxide ions, OH, as shown in the equation below. NaOH ∏ Na OH Copyright © by Holt, Rinehart and Winston. All rights reserved. Eco Connection onnection Acid Precipitation Acid precipitation, more commonly called acid rain, describes rain, snow, sleet, or fog that contains high levels of sulfuric and nitric acids. These acids form when sulfur dioxide gas, SO2, and nitrogen oxide gas, NO, react with water in the atmosphere to produce sulfuric acid, H2SO4, and nitric acid, HNO3. Acid precipitation makes soil and bodies of water, such as lakes, more acidic than normal. These high acid levels can harm plant and animal life directly. A high level of acid in a lake may kill mollusks, fish, and amphibians. Even in a lake that does not have a very elevated level of acid, acid precipitation may leach aluminum and magnesium from soils, poisoning water- dwelling species. Reducing fossil-fuel consump- tion, such as occurs in gasoline engines and coal-burning power plants, should reduce high acid levels in precipitation. Sulfur dioxide, SO2, which is produced when fossil fuels are burned, reacts with water in the atmosphere to produce acid precipitation. Acid precipitation, or acid rain, can make lakes and rivers too acidic to support life and can even corrode stone, such as the face of this statue. FIGURE 2-13 44 CHAPTER 2 This solution then contains more hydroxide ions than hydronium ions and is therefore defined as a base. The adjective alkaline refers to bases. Bases have a bitter taste; however, never taste a substance to test for alkalinity. They tend to feel slippery because the OH ions react with the oil on our skin to form a soap. In fact, commercial soap is the product of a reaction between a base and a fat. pH Scientists have developed a scale for comparing the relative con- centrations of hydronium ions and hydroxide ions in a solution. This scale is called the pH scale, and it ranges from 0 to 14, as shown in Figure 2-14. A solution with a pH of 0 is very acidic, a solution with a pH of 7 is neutral, and a solution with a pH of 14 is very basic. A solution’s pH is measured on a logarithmic scale. That is, the change of one pH unit reflects a 10-fold change in the acidity or alkalinity. For example, urine has 10 times the H3O ions at a pH of 6 than water does at a pH of 7. Vinegar, has 1,000 times more H3O ions at a pH of 3 than urine at a pH of 6, and 10,000 times more H3O ions than water at a pH of 7. The pH of a solution can be measured with litmus paper or with some other chemical indicator that changes color at various pH levels. Buffers The control of pH is important for living systems. Enzymes can function only within a very narrow pH range. The control of pH in organisms is often accomplished with buffers. Buffers are chemi- cal substances that neutralize small amounts of either an acid or a base added to a solution. As Figure 2-14 shows, the composition of your internal environment—in terms of acidity and alkalinity— varies greatly. Some of your body fluids, such as stomach acid and urine, are acidic. Others, such as intestinal fluid and blood, are

What Pet Should You Get? Introduction. Almost every kid has wanted to have a pet. Pets can make good friends. But how do you decide which kind of pet to get? Here are some kids who have some opinions about pets. Read what they have to say. Then decide what kind of pet you would like to have. Dogs as Pets. Every kid should own a dog. A dog comes when you call it. You know it likes you because it wags its tail. Dogs like to play chase with you. Some dogs will even play catch! Get a dog for a great playmate! Dogs as Pets. Dogs are hard pets to keep. They need lots of space to run. What if you don't have a yard? You have to take them on walks even if it is cold. The worst thing is that you have to clean up after them. Yuck, who wants a dog? Lizards as Pets. Lizards make the coolest pets. They don't bark or meow. You don't have to take them for walks. They are easy to hold and to pet. It doesn't cost much for lizard food. So, go get a lizard! Lizards as Pets. It is mean to keep lizards as pets. Some have to stay in one tiny box their whole life. Some of them eat live crickets. Plus, it feels really weird to pet them. Never, ever, get a lizard! Fish as Pets. Fish make awesome pets. They come in such pretty colors. It is fun to watch them swim back and forth. It is fun to watch their funny mouths. They only need to be fed once a day. Fish make fun and easy pets to keep. Fish as Pets. Fish should be left in the oceans and rivers. Fish don't come when you call them. They can't do any tricks. And worse than that, fish don't like to be touched. Fish win the most boring pet award. Parrots as Pets One of the best pets to own is a parrot. Parrots are very beautiful birds. They often do not need a cage. I love it when my parrot says "hello." Some parrots even whistle. Get a parrot and teach it to talk. Parrots as Pets Parrots are really messy pets. They spill seeds and fruit all over. They are not the best drinkers. They get water on the floor. Their feathers can even fall out. Don't get a parrot unless you like cleaning! Conclusion. There are good things and bad things about each pet. You have to decide whether the good things are great. You have to decide whether the bad things are okay for you. You also have to do research to see whether your house is good for a pet. Don't get a pet unless you have thought hard about it. But the right pet can be your best friend!

Class activity 1: Crop distribution refers to how crops are spread across different regions in Nigeria. Certain crops are found more in one area than the rest because of the environment in which they grow best. Successful adaptation of crops to the climatic and soil conditions of an area is known as Adaptability. Different crops require different climatic and soil conditions for their normal growth and development. THREE ECOLOGICAL REGIONS IN NIGERIA 1. Coastal region 2. Rainforest region 3. Savanna region Coastal region: This region is close to the sea and is marked by mangrove forest. The climate there is humid and receives lots of rainfall. Dominant Crops: Rice, rubber, coconut. States found: Akwa-Ibom, Bayelsa, Cross-Rivers, Delta, Edo, Lagos, Ogun, Ondo and Rivers. RAINFOREST REGION(SOUTH): This region experiences high rainfall throughout the year and lush vegetation. Dominant Crops: Oil palm, banana, plantain, kolanut, cocoa, tubers(cassava and yam). States found: Bayelsa, Cross River, Edo, Ekiti, Ondo, Osun, Rivers, and Taraba. SAVANNAH REGION(NORTH): This region has a dry and wet season with less rainfall than the forest region. It consists of grassland and a few trees. Dominant Crops cereals, legumes, and cotton. These crops adapt to the drier and warmer climate of the savannah and require less water. States found: Enugu, Ekiti, Osun, Oyo, Kwara, Kogi, Benue, Nassarawa, Plateau, and Taraba States

1. Settlements Importance of Rivers Fertile Land: The soil near rivers was great for farming, thanks to regular flooding that added nutrients. Trade and Travel: Rivers made moving things and people easy, which helped trade and communication. Protection: Rivers could act as natural barriers, making it harder for enemies to attack. Food: Rivers were full of fish and other food, adding to what people could eat. Energy: People used the river's flow to power machines, for example, grinding grain. Cleanliness: Rivers were used to wash away waste, keeping settlements cleaner. Culture: Rivers often had spiritual importance, and ceremonies and stories revolved around them. Common Geographic Features of Ancient Civilizations Mesopotamia: the Tigris and Euphrates Rivers in central Iraq Indus River Valley: the river runs in the northwestern part of India Nile River Valley: the major river of Egypt Yellow River Valley: a major river flowing through the southern part of China Rivers provided water, food, transportation, and shaped the way of life and development of these ancient civilizations. Impact of Mountains on Settlements Mountains served as barriers to early settlement due to the lack of technology to cross them. The Himalayan Mountains isolated much of India and China during their early development. Impact of Deserts on Migration Deserts posed significant challenges to people who wanted to migrate due to their harsh and unforgiving conditions. Notable deserts include the Empty Quarter in Saudi Arabia and the Sahara Desert in Africa. Changes in Migration and Cultural Blending Advancements in transportation technology post-Industrial Revolution increased cultural blending. Transportation advancements enabled global migration. Before, cultures were isolated, focusing on beliefs and local adaptations. The Industrial Revolution transformed migration and cultural blending. 2. How Humans Modify and Adapt to Their Environment Ways Humans Modify Their Environment Mining: Removing the earth's surface for precious metals. Irrigation: Diverting water for farming. Transportation: Moving goods with trains, cars, airplanes, and boats. Mining Strip mining removes large layers of the earth. Can impact the environment by removing plants and polluting water sources. Irrigation Diverting water for farming and urban development. Transportation Moving goods using trains, cars, airplanes, and boats. Human Adaptation to the Environment Adjusting to environmental conditions by changing behavior. Examples: Wearing specific clothing, using specific building materials. Human Modification of the Environment Changing the earth to meet human needs by physically altering the environment. Examples: Dams, canals, roads, bridges. Impact of Weather and Geological Events on Humans Events like earthquakes, hurricanes, and cold weather affect human settlements. Examples: Building earthquake-resistant buildings, creating levees, using ice for tourism. 3. Understanding Culture Introduction to Culture Culture refers to the way of life of a group of people who live in a particular place. It includes traditions, beliefs, values, and the way they do things. Cultural Characteristics Religious traditions Language Family values Laws Cultural characteristics make each culture unique. Cultural Representations Art Architecture Music Literature Cultural representations express a culture's creativity and show their beliefs and history to the world. Government and Culture Types of government reflect cultural beliefs and traditions. Examples: democratic republic, communist state. The way a country is governed tells a lot about its culture. Economic Systems and Cultures Economic systems reflect cultural values. Examples: bartering, modern economies (e.g., United States, China). How people earn and spend money also reflects their culture. Spread of Cultural Ideas Trade: Spreading ideas through interactions during trade. Travel: Visitors bringing new ideas. War: Conquering armies imposing beliefs. Cultural ideas spread through trade, travel, and war. Multicultural Societies Blending of multiple cultural and ethnic groups. Common in advanced societies with immigration. Multicultural societies create something new by bringing together different cultures. Cultural Adaptation Cultures can change and adapt by taking new ideas and blending them with their own traditions. Example: 'Tex-Mex' food, which blends Mexican and Texan traditions.

In a single domesticated grain seed, one might see the bud of great civilizations. The birth of agriculture was a turning point in humans' social development, as stable food supplies enabled people to transcend the constraints of food gained by hunting and gathering. After that, people were able to settle down and experience population booms. As one of the major areas around the globe where agriculture originated, China has contributed to the world's domesticated rice, millet, buckwheat and soybeans. Archaeological studies have unveiled that the planting of rice originated around 10,000 years ago in the lower reaches of the Yangtze River, leading to the eventual replacement there of hunting and gathering practices dating back 5,000 to 6,000 years. "It marked the formation of a rice-based agricultural society in the area," said Zhao Zhijun, an archaeologist at the Chinese Academy of Social Sciences. Archaeological studies of the origins of rice-based agriculture are an important part of a national project tracing the origins of Chinese civilization itself. President Xi Jinping has greatly valued the project. At a group study session of the Political Bureau of the Communist Party of China Central Committee on May 27, 2022, Xi, who is also general secretary of the CPC Central Committee, emphasized the significance of the project and the role that archaeological studies play in better understanding Chinese civilization. The project to trace the origins of Chinese civilization, in addition to finding signs of human activity more than 1 million years ago, has also proved that China's history includes 10,000 years of culture and more than 5,000 years of civilization. The project has provided clear knowledge of the origins and formation of Chinese civilization, the history of its development, the process of the formation and development of its pluralistic and integrated pattern, and the characteristics of the civilization and why it was formed in such a way, he added. This was not the first time that Xi emphasized the importance of the origin-tracing project. Since the 18th National Congress of the CPC in 2012, Xi has toured more than 100 historical and cultural locations and issued many instructions related to archaeology and the origin-tracing project. During the 23rd group study session of the Political Bureau of the CPC Central Committee in 2020, Xi called for giving more attention to archaeological research and letting historical facts speak for themselves. "This will provide strong support for our efforts to carry forward the best of traditional Chinese culture and increase our cultural confidence," said Xi. The origin-tracing project has been carried out since 2002. Its ongoing fifth phase, which started in 2020, involves the participation of more than 500 researchers from 29 institutes across the country. It primarily centers on several ancient capital sites, including the Liangzhu site in Hangzhou, Zhejiang province, the Taosi site in Xiangfen county, Shanxi province, the Shimao site in Shenmu, Shaanxi province, and the Erlitou site in Luoyang, Henan province, from 3,500 to 5,500 years ago, as well as other settlements mainly along the basins of the Yellow, Yangtze and Liaohe rivers. The project has also expanded to a wider geographic and chronological framework to decode how Chinese civilization emerged and how its diverse elements formed a unity. Excavation of the Liangzhu site, which is over 5,000 years old and is one of the major sites covered in the origin-tracing project, has yielded an inner city covering 3 million square meters and an outer city of 6.3 million sq m, making it the world's largest capital at the time. It also had a giant water control system, which contributed to the formation of a rice-based agricultural society. By calculating the earthwork volume, archaeologists found that building the entire ancient city, the water control system and Mojiaoshan — a 10-meter-tall man-made terrace in the center of the city — required 10,000 people working daily for seven-and-a-half years. The discoveries show that Liangzhu had a kingship able to organize people for large-scale public construction, and its social differentiation, emergence of the city concept and existence of a kingship prove that it became a civilized society, said Wang Wei, a veteran archaeologist at the Chinese Academy of Social Sciences. Significant topic Wang said that tracing the origins of a civilization is a significant topic in the research of human history. Over the years, the Chinese project has provided China's answer to how to define civilizations. In 2022, Xi commended the efforts and stressed that the project has made creative contributions to the research on tracing the origins of the world's civilizations. Wang said: "International academia has proposed three indispensable elements for a civilized society based on features of Mesopotamian and Egyptian civilizations: written characters, metallurgy and the city concept. But we can find that some of the three elements were absent in many ancient civilizations. For example, the Mayan civilization had no metallurgy, while the Incan civilization didn't have written characters." Western scholars believe that Chinese civilization began with the Yinxu Ruins in Anyang, Henan province, a capital of the late Shang Dynasty (c.16th century-11th century BC), based on the discovery of inscribed oracle bones from that time. However, Chinese archaeologists don't agree. With continued archaeological research, international academia now believes that places around the world can propose criteria for civilization based on their own ancient social development. China's archaeological studies have shaped the nation's criteria in defining a civilization: the development of productivity, an increase in population, the appearance of cities, social differentiation and the emergence of kingship and state. "These criteria are suitable for identifying other civilizations as well," said Wang. "Civilizations have in common the appearance of kingship and state. They are only different in the ways of imposing kingship and the forms of state." In China, kingship and state "were shown by exquisite jade and bronze ritual artifacts, grand palaces and magnificent mausoleums imitating aboveground palaces", he added. "In Mesopotamia and ancient Egypt, they were demonstrated through superb stone temples, pyramids and large-scale tombs." Multidisciplinary subject President Xi said in 2020 that archaeologists should work closely with researchers from other fields to make an interpretive analysis of material remains. Zhang Chi, a professor of archaeology at Peking University, said that since material remains are often the research focus of archaeological studies, these should not only be observed with the eyes, but also studied using scientific and technological tools. Therefore, from the perspective of research methods, archaeology is by nature a multidisciplinary subject, Zhang added.

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