EARTH SCIENCE BACKGROUND READING

Table of Contents

Page Topics

1……………………………..………………………. Table of Contents

2……………………………..………………………. Earth's Systems Interactions

4……………………………..………………………. Geoscience Processes

6……………………………..………………………. Weathering and Erosion

9……………………………..………………………. The Water Cycle

11……………………………..…………………….. Earth Materials

15……………………………..…………………….. Geologic History of Earth

17……………………………..…………………….. Seafloor Spreading

18……………………………..…………………….. Formation of The Solar System

From: Accelerate Learning, Inc. 2016

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Earth's Systems Interactions with Earth’s Systems Review-ESS2-1: I CAN develop a model using an example to describe ways the geosphere, biosphere, hydrosphere, and/or atmosphere interact.

The planet Earth is a set of interconnected systems that function to provide resources that support life. There have been constant changes on Earth since the time it was formed approximately 4.6 billion years ago. These changes have occurred over both short and long periods of time. The systems on Earth are responsible for these changes.

Earth’s surface includes many formations such as continents, bodies of water, glaciers, mountains, valleys, canyons, and caves. The formation of these structures is the result of gradual and sudden events such as precipitation, erosion, hurricanes, tornadoes, earthquakes, volcanic eruptions, floods, and freezes. Ice, wind, and moving water weather and erode Earth’s surface, breaking down rock and soil and moving it to different locations. Weathering and erosion are both responsible for both creating new soil deposits (deposition/sedimentation). Erosion is also responsible for washing away fertile soil.

Soil contains living and nonliving components and it holds the largest amount of biodiversity of all systems. Soil supports life on Earth. It is also provides the resources for food, building materials, and energy that living things need for survival. Soil also plays a role in the planet’s climate through the exchange of water and energy between the biosphere and the atmosphere. Soil supports the breakdown and synthesis of organic materials by supplying organic and inorganic building blocks, such as carbon, nitrogen, and other trace minerals.

The hydrologic, or water, cycle is central to connecting Earth’s systems. It is powered by energy from the Sun. The cycle of precipitation, evaporation, infiltration, freezing, melting, and condensation moves water between the

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clouds, land, oceans, and back to the clouds. Energy is exchanged as water moves through the cycle, causing natural variation in global climates. Climate is the long-term pattern of temperature and weather and is impacted by the absorption and release of heat. When water evaporates, it removes heat from the surrounding environment. Condensation causes the release of heat and the warming of the environment. Oceans release and absorb heat more slowly than land. During winter, oceans are warmer than the surrounding land.

Climate is determined by the energy provided by the Sun. On any given day, different parts of Earth’s surfaces are heated by different amounts because at different latitudes the Sun rises in different places, climbs to different heights in the sky, and is up for different amounts of time. The amount of heating at any given place varies seasonally because Earth’s axis is tilted compared to a line perpendicular to the plane of its orbit around the Sun. If the axis was along this line, rather than tilted 23 ½ degrees from it, there would be no seasons. The intensity of energy from the Sun on Earth’s surface is impacted by cloud cover, and proximity to mountains and oceans. The Sun is up for different lengths of time and moves on different paths through the sky in different places each day. The path of the Sun and axial tilt cause fluctuation in the heating of Earth’s surfaces. Because the Sun heats Earth unevenly, areas of high and low pressure occur. Wind is caused by the movement of air from areas of high pressure to low pressure. Climate also results from the interaction between landforms and bodies of water. Weather is different from climate, and is the short-term condition that occurs in specific regions when energy and water are moved into and out of the atmosphere. Winds and clouds in the atmosphere interact with landforms to create weather patterns. Destruction of the ozone layer caused by the use of chlorine and bromine-rich chemical compounds throughout much of the twentieth century also affects climate. Earth is a set of complex systems in which chemical elements and the building blocks of life are recycled between Earth’s surface, the oceans and landforms and the atmosphere.

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Geoscience Processes with Earth Materials MS-ESS2-2: I CAN construct an explanation based on evidence for how geoscience processes have changed Earth’s surface at varying time and spatial scales.

Geoscience processes are the interconnected processes that occur in the geosphere, hydrosphere, atmosphere, and biosphere. These processes can result in events that occur at different spatial scales and over different periods of time.

Some events such as landslides and geochemical weathering and erosion occur relatively quickly and affect a relatively small area of Earth. Landslides occur when the mass of the rocks and soil covering a slope become too heavy and are pulled down the slope by gravity. The increase in mass often occurs as the result of an increase in the moisture level of the soil.

Caverns are formed when acidic groundwater flows through limestone layers. The acid reacts with the calcium carbonate to break down the limestone. Over time cracks and holes in the limestone layer form. While this process occurs to a relatively small area and the reaction occurs quickly, it takes a very long time for actual caverns to form.

Some events take a very long time to occur and occur at very large scales. Tectonic plate movement is such an example. Plate movements of a few centimeters a year can result in entire crustal plates moving to new locations on Earth’s surface. A collision between two plates can form mountain chains such as the Himalaya. This is a very slow process. The formation of the Himalaya occurred over a period of 40 to 50 million years.

Another category of geoscience processes is those events that develop very slowly but cause a sudden catastrophic event. Volcanic eruptions and earthquakes both result from the slowly building pressure of two tectonic

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plates pushing and moving toward or against each other. Another example of this type of event is a meteor strike. A meteoroid can travel through space for millions of years before coming close enough to Earth to enter its atmosphere as a meteor.

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Weathering and Erosion with The Water Cycle, Water in the Atmosphere, Water on Earth MS-ESS2-2: I CAN construct an explanation based on evidence for how geoscience processes have changed Earth’s surface at varying time and spatial scales.

Weathering is the process of either chemically or physically breaking down rock. If a rock is chemically weathered, it is chemically altered or dissolved. Air and water are common agents of chemical weathering. Water can dissolve and remove minerals from rocks. When carbon dioxide in the air dissolves in rainwater, it acts as a mild acid and degrades the rocks that it contacts.

Limestone caverns form when water with a high concentration of carbon dioxide flows as groundwater through the buried layers of limestone. The carbon dioxide forms an acid with the water and causes a chemical reaction that dissolves the limestone. This creates openings in the rock as the acidic water flows through widening cracks and crevices. This is a very slow process, but over time, large passageways are formed. The continued dripping of the sediment-filled water forms the beautiful formations of stalagmites and stalactites. Water that drops its sediment when it hits the ground forms stalagmites that rise from the floor of the cave. Water that drops its sediment before falling to the ground forms stalactites that hang from the ceiling of the cave. Chemical weathering can weaken rocks and make them more susceptible to physical weathering, but these two processes do not always occur together.

If a rock is physically weathered, it is broken into smaller pieces through mechanical processes. For instance, the movement of the crust due to plate tectonics can cause fractures in rocks, breaking them into smaller parts. Frost wedging is another physical weathering process where water seeps into

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cracks in rock, then freezes and expands, which makes the cracks larger. As this process is repeated (over a winter or over years), the cracks get bigger and bigger until the rock breaks into multiple pieces.

In addition, organisms cause both chemical and physical weathering. Bacteria and algae produce acid, and when they live in cracks in rocks, this acid acts as a chemical weathering agent. Trees and animals can act as physical weathering agents. Tree roots can grow into rocks and break them apart. We can see this when we walk over sidewalks that have been cracked by the trees growing next to them. Animals can also break rocks by burrowing into them.

Once rocks have been broken into smaller pieces, or sediment, either through chemical and/or physical weathering, they can then be moved to a new location. Erosion is the process of moving rock or sediment from one area to another. There are several different forces that can act as agents of erosion. These include water, wind, ice, and gravity. The influence of water, wind, and ice varies. The more powerful these erosional agents, the bigger the pieces of sediments they move. For example, a slight breeze can blow dirt and sand around, but hurricane-force winds can move small boulders. Typically, water in rivers moves sediment from upstream to downstream, and the water usually deposits or drops off that sediment into beaches, bays, gulfs, or oceans. This process is called deposition.

Wind moves sediment along Earth’s surface and is an important erosional agent in flat areas, such as in deserts or on the plains. Ice is one of the most powerful erosional agents. A glacier can drag large boulders under its ice and deposit the boulders hundreds to thousands of miles away. Gravity moves rocks and sediments downhill. Landslides and mudslides are erosional events where rocks and sediments are moved from a high elevation to a low elevation (due to gravity). Eroded materials are deposited when gravity overcomes the force of the erosional agent. For example, in a river, sediments deposit when the force of the moving water can no longer overcome the force of gravity. Weathering, erosion, and deposition can lead to changes in Earth’s surface by making landforms.

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The focus of this unit is water and ice as agents of weathering and erosion that changes the shape of Earth’s surface. Various weathering and erosional effects from water include: flowing water from streams, rivers, runoff, snow/ice melt and floods, wave action from oceans and lakes, and freeze-thaw due to variations in temperature.

A river starts in high elevations and runs across the land eventually reaching another body of water, like the ocean. Rivers can carry large amounts of water and sediment that continually reshape the land by weathering, erosion, and deposition. Weathering is the breaking apart, or wearing down, of rocks into sediment. The weathered materials are moved to a different location during erosion. The faster water flows, the more energy is available to carry weathered material. These particles are deposited when the speed of the river slows down and loses the energy. The deposition of the particles (sediment) creates new landforms.

Glaciers are the primary example of ice as an agent of weathering and erosion. There are two types of glaciers: alpine (in mountainous regions) and continental. Alpine glaciers carve out the majestic, rugged, mountain valleys. Continental glaciers are massive blankets of ice covering thousands of square miles. A modern example of a continental glacier is in Antarctica. Both alpine and continental glaciers work as powerful erosional bulldozers, moving massive amounts of rock materials. Glaciers can gouge out portions of rocks to create landforms like the Great Lakes. Glaciers also create landforms when they melt and the rock and sediments they carry are deposited. Nantucket Island, off the coast of Massachusetts, was formed from glacial deposits. Evidence of the power of glaciers can be studied in the glaciers of today and in the sediments left in previously glaciated regions of the world.

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The Water Cycle with Weathering and Erosion, Water in the Atmosphere, Water on Earth MS-ESS2-4: I CAN develop a model to describe the cycling of water through Earth’s systems driven by energy from the sun and the force of gravity. The Roles of Water in Earth’s Surface Processes.

Earth’s water travels through a continuous cycle, moving between the geosphere, hydrosphere, atmosphere, and biosphere as the result of phase change and chemical reactions.

When liquid water in the hydrosphere is heated or gains radiant energy from the Sun, evaporation occurs. The molecules begin to move quickly and change phase to form water vapor, the gas form of water. When water vapor rises into the atmosphere, cools, and loses energy, condensation occurs. The molecules slow as the gas changes phases once again to form a liquid. The resulting water droplets cling together to form clouds.

Precipitation occurs once the collected droplets become heavy and are pulled to Earth by gravity. The cycle then leaves the atmosphere with the water either entering the geosphere or returning to the hydrosphere.

Water that soaks into the soil is collected by the roots of plants and is carried to the leaves. Plants combine radiant energy from the Sun, carbon dioxide from the atmosphere, and water to perform the chemical reaction of photosynthesis. When the product of the chemical reaction, glucose, is used by the plant for energy, a second chemical reaction, chemical respiration, occurs. As a result of this reaction, transpiration occurs as water is released from the plant back into the atmosphere.

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*Special Note The current trend in the scientific community is to refer to the water cycle as the hydrologic cycle. This change in terminology is based on the concept that the molecules of H20 change state between liquid (water) and solid (ice) and gas (water vapor) depending on the conditions and stage of the cycle. Students need to be aware the cycle may be referred to as either the water cycle or the hydrologic cycle in literature and on standardized tests.

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Earth Materials with Geoscience Processes MS-ESS2-1: I CAN develop a model to describe the cycling of Earth’s materials and the flow of energy that drives this process. Earth’s Systems Interact

Earth’s major systems are the geosphere (solid and molten rock, soil, and sediments), the hydrosphere (water and ice), the atmosphere (air), and the biosphere (living things and humans). These systems interact in multiple ways to affect Earth’s surface materials and processes. All of Earth’s processes are the result of energy flowing and matter cycling within and among the planets systems. This energy is derived from the Sun and Earth’s hot interior. The energy that flows, and the matter that cycles, produce chemical and physical changes in Earth’s materials. The rock cycle is typical of such interactions. The Rock Cycle

The rock cycle illustrates how rocks move on and under Earth’s crust and change from one type of rock into another. As rocks move through the rock cycle, their mineral compositions and physical structures change in order to reflect the processes under which they are formed. The rock cycle shows how any rock can undergo changes to become another rock. For example, an igneous rock formed by volcanic lava flow can crumble to become sand. The sand can be deposited on a beach and can eventually be compacted and cemented to become a sedimentary rock. The sedimentary rock can be buried deep into Earth’s crust where extreme pressure and heat from the overlying layers change the rock into a metamorphic rock. Any rock can be carried so deep that the rock melts from the temperature, becomes magma, and moves toward the surface to form new igneous rocks. Unlike life cycles, rocks do not have to move through each stage. An igneous rock can be changed into a

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metamorphic rock, a metamorphic rock can crumble to become a sedimentary rock, and a sedimentary rock can be remelted to become magma. The path a rock takes in the rock cycle depends upon the movements of the rock, which places it in the position to crumble, be put under

great pressure, or melt. Rocks can be classified into three categories based on their formation.

Rock Formation

Igneous rocks are formed through volcanic action. Magma that cools slowly and deep within Earth forms intrusive igneous rocks like granite. Magma that reaches the surface as lava flowing from volcanoes, cools more quickly to form igneous rocks, like basalt or pumice. Some lava explodes and cools so quickly in the air that no crystals form, and the high silica content, with little water, solidifies it into a glassy rock called obsidian. Existing rocks continue to move through the rock cycle. Some are buried deep under other rocks. Layers can be recycled by heat and pressure and turned into metamorphic rocks, or they can erode on the surface into sediments and be compacted into sedimentary rocks.

Sedimentary rocks, such as sandstone or limestone, are formed by deposition. When Earths weathered materials are deposited in layers and pressed together over time, sedimentary rocks form. As layers are added, the oldest or lower layers that were deposited, experience increased pressure. The sediments and the spaces between them are crushed together in a process called compaction. During the cementation process, the sediments are bound together when a solution fills in around the particles like glue. A quiet and

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undisturbed environment will sometimes lead to animal and plant fossil formation within the layers of sedimentary deposition.

Metamorphic rocks, such as marble or gneiss, form when one type of rock changes into another due to exposure to heat and pressure. This is often caused by the movement of materials deep beneath Earth’s surface. This change to a rock’s appearance and composition takes an extremely long time. Metamorphic

rocks are often characterized by wavy layers of minerals or by the presence of unusual minerals. The interesting thing about the metamorphic process is that any rock (igneous, metamorphic, or sedimentary) will change and form new metamorphic rocks when given enough time, heat, and/or pressure.

Other Earth Materials

Other Earth materials are cycled through the geosphere, atmosphere, and hydrosphere as a result of energy and the life cycle of living organisms. As organisms die, they are decomposed, and matter is cycled through the carbon, oxygen, and nitrogen cycles. Energy from the Sun drives the movement of water and gases in the atmosphere and provides the energy source for photosynthesis to cycle carbon, water, oxygen, and nitrogen.

Carbon and Oxygen Cycles: In living systems, plants absorb carbon dioxide gas during photosynthesis and use the carbon to produce other carbon-containing molecules, such as sugars and starches. Consumers obtain energy from these molecules (from producers) and break them down

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into simpler molecules through respiration. Carbon dioxide gas releases during respiration. Oxygen also cycles through living systems. Producers release oxygen during photosynthesis, and most organisms take in oxygen and use it during respiration. Another source of carbon that enters an ecosystem is through the release of carbon dioxide and carbon monoxide from burning fossil fuels and vehicle exhaust.

Nitrogen Cycle: Nitrogen moves from the air, to the soil, into living things, and back into the air. Free nitrogen in the atmosphere is combined with other elements through nitrogen fixation. This process is done by nitrogen-fixing bacteria. Nitrogen is fixed into compounds used by other organisms. For example, consumers eat nitrogen compounds in plants to build proteins and other substances. Decomposers break down waste and the remains of organisms and return nitrogen compounds to the soil. Certain bacteria releases some free nitrogen back into the air. Biomass is organic material from plants and animals. When living organisms die, bacteria and other decomposers break down the materials (breaking larger molecules into smaller ones) in biomass. The decay of biomass produces matter in the form of small molecules and releases energy stored in the chemical compounds in biomass.

The energy that drives the carbon, oxygen, and nitrogen cycles and also powers the interactions among Earth’s hydrosphere, biosphere, geosphere, and atmosphere, comes from two sources: the Sun, and the core at the Earth’s interior.

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Geologic History of Earth with Seafloor Spreading MS-ESS1-4: Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth’s 4.6-billion-year-old history.

Stratigraphy is the study of rock layers and layering. Scientists use stratigraphy to determine the geologic events that formed rocks and the order in which these events occurred. The principle of Uniformitarianism states that the geologic processes which shape Earth today are the same as they were in the past, or “the present is the key to the past.” In general, sediments and rocks are deposited horizontally so each rock layer is older than the layers above it. This is known as the Law of Superposition. Sometimes rocks can be moved by geologic processes such as folding, faulting, erosion, and the intrusion of magma. By looking at all of the rock layers and the events that occurred, we can determine the order of events and determine the age of rock layers relative to the rocks around them.

Index fossils are fossils of organisms that lived for a short period of time, but were widespread geographically. So, if an index fossil is found in rock layers, geologists can use the fossil to determine the age of the rock layer.

Earths history can be divided into segments called eras, periods, and epochs. The divisions in the Geologic Time Scale are placed to

correspond to major events that have occurred in Earths history, such as mass extinctions. These events vary in time and duration, so the time segments are not equal. As a result, it is important to remind students that there will be variations in times among different formations of the time scale. Because it

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covers billions of years and much of the findings are based on relative data, scientists are always making changes to the scale.

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Seafloor Spreading with Geologic History of Earth MS-ESS2-3: Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.

Seafloor spreading is one of the geological processes that is constantly changing Earth’s crust. The Theory of Plate Tectonics became widely accepted during the 1960s when scientists discovered seafloor spreading. Scientists were able to use new technology (echo sounding) to find ocean features such as trenches and mid-ocean ridges. Harry Hess proposed that at mid-ocean ridges, magma flows up from the mantle and forms new crust on both sides of the ridge. This new crust makes the ocean floor wider and pushes the continents surrounding it farther away from each other. Drilling of the seafloor confirmed that oceans are youngest along mid-ocean ridges and oldest along their edges. The mid-Atlantic ocean ridge is part of the global mid-ocean ridge system made of many connected mid-ocean ridges. The mid-Atlantic ridge has been making new oceanic crust for millions of years, allowing the Atlantic Ocean to get bigger and pushing North and South America farther away from Europe and Africa. When oceanic crust and continental crust collide, the thinner yet denser oceanic crust dives below the thicker yet lighter continental crust forming a deep trench. As the oceanic crust sinks into the mantle it melts and the recycling process begins. As a result, volcanic mountain ranges form along the continental crust, and earthquakes are common in the area.

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Formation of The Solar System The Earth’s Place MS-ESS1-2: The student is expected to develop and use a model to describe the role of gravity in the motions within galaxies and the solar system.

Our solar system is one of many that formed in our Milky Way Galaxy. 4.6 million years ago, a gravitational collapse of a dense cloud of gas and dust ignited star formation caused by the explosion of a supernova that disturbed our corner of the Milky Way. Gravity caused the cloud to fall in on itself and spin. Eventually, the cloud grew hot enough in the center. that a star, our Sun, was born. The spinning caused the cloud to flatten like a disk. As the disk spread, gravity caused bits of dust and gas to begin to stick together and form clumps. Scientists have observed other stars that still have disk-shaped clouds around them called protoplanetary disks. Some clumps became planets or moons. Near the center of the cloud, where planets like Earth formed, only rocky material withstood high temperatures. In the outer regions of the disk, icy matter, along with gases and some rocky material, formed the giant planets like Jupiter. Debris left over from the formation of the solar system created asteroids, comets, and assorted frozen worlds, like Pluto and other Kuiper Belt objects, in the deep freeze of the outer solar system. All planets move around the Sun in the same direction that the Sun rotates. The inner planets are smaller and denser than the outer planets and are made of metal and silicates. The outer planets are made mostly of hydrogen. The asteroids are made of rock and metal and are located between the orbits of Mars and Jupiter. Comets appear to be made mostly of ice, with a great deal of trapped or frozen gases like carbon dioxide.

Gravity’s Role

Gravity not only played an important role in the formation of the solar system, but continues to govern its motions. Gravity is an attractive force that depends on mass and distance. The more massive an object is the more gravitational

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force it has. The closer two objects are, the more gravitational force is between them. The gravitational pull of the Sun keeps the planets in their orbits. The gravitational pull of Earth keeps the Moon in its orbit. When objects get too close to each other, they can collide. Small objects like meteorites, comets and asteroids frequently collide with planets and moons.

Formation of the Universe

Gravity also played an important role in the formation of the universe. The universe began about 13.8 billion years ago with the Big Bang. Within seconds after that explosive expansion, atoms were formed. Gravity pulled these atoms together into bodies, eventually forming stars and planets. Stars explode in supernovae, spewing matter into clouds. Another supernova disturbed one cloud, leading to the formation of the solar system containing Earth.

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