Earth Science PDF

EARTH SCIENCE Water Sources: Surface Water: the freshwater from WATER RESOURCES: sources of water precipitation and melted snow that flows that are useful or potentially useful to across the earth’s land s...

EARTH SCIENCE Water Sources: Surface Water: the freshwater from WATER RESOURCES: sources of water precipitation and melted snow that flows that are useful or potentially useful to across the earth’s land surface and into humans. It is important because it is lakes, wetlands, streams, rivers, estuaries needed for life to exist. and oceans. - Many uses of water include agricultural, industrial, household, Surface Runoff: precipitation that does recreational and environmental not infiltrate the ground or return to the activities. atmosphere by evaporation - Water: Earth’s surface is covered by 71%. Essential for life, we can Watershed: describes the total area only survive a few days without contributing drainage to a stream or river. water. The land from which surface water drains into a particular body of water. May be applied to many scales –A large watershed is made up of many small watersheds. Groundwater: precipitation that seeps into the ground and percolates downward through spaces into soil, gravel and rock until an impenetrable layer of rock stops. Zone of saturation: spaces underground that are completely filled with water Water table: top of zone of saturation Aquifer: water saturated layers of sand, gravel or bedrock through which groundwater flows. Recharge slow ~ 1 meter per year Use of Water Resources Humans directly or indirectly use about 54% of reliable runoff Withdraw 34% of reliable runoff for: - Agriculture – 70% - Industry – 20% - Domestic – 10% Leave 20% of runoff in streams for human use: transport goods, dilute pollution, sustain fisheries We could use up to 70-90% of the reliable runoff by 2025  Groundwater Pollution Too Much Water: Floods - Agricultural products - Natural phenomena - Underground storage tanks - Aggravated by human activities - Landfills - Causes: Rain or snow, impervious - Septic tanks surfaces, removal of vegetation, draining wetlands, living on Growth of population floodplains, deforestation Supply & demand are in growing conflict: supply is finite – water Tapping Groundwater management driven by values and needs - Year-round use - No evaporation losses Increases demand/use of water - Often less expensive Potential Problems: Increases land use and changes Water table lowering: too much use vegetation and permeability Depletion: groundwater being withdrawn at 4x its replacement rate Increases demand for instream values Saltwater intrusion: near coastal areas – instream flows are for people Chemical contamination Reduced stream flows SOIL: a living, dynamic system with organic and inorganic components. Soil is Pollution Source terminology a product of its environment and parent Point source: pollution comes from material. single, fixed, often large identifiable sources Components: - smokestacks By volume: - discharge drains - 45% mineral - tanker spills - 5% organic material Non-point source: pollution comes from - 50% space (air/water) dispersed sources. By mass: - agricultural runoff - 0% air - street runoff - 18% water - 80% mineral Types of Water Pollution - 2% organic material Sediment: logging, roadbuilding, erosion 1. The mineral component Oxygen-demanding wastes: human - inorganic waste, storm sewers, runoff from - “mineral”: agriculture, grazing and logging, many - Primary: original others components of earth crust - Secondary: new minerals Disease-causing organisms: from made by weathering of untreated sewage, runoff from feedlots earth’s crust - divided by particle size: Toxic chemicals: pesticides, fertilizers, Sand, silt, clay industrial chemicals - mineral make-up due to: a. Parent Material: material on Heavy metals: lead, mercury and in which soil develops  differ from the layers above and b. How resistant minerals are: beneath Soluble minerals are readily LEACHED (washing off of elements from the soil) from soil profile (Ca,Mg,Na) Certain minerals tend to accumulate in soil (oxides of Fe, Al, Si) c. Climate: Amount of leaching and rate of weathering. d. “Age” 2. Organic Component - Living (primarily decomposers such as fungi and bacteria) - Non-living (dead and all in-between stages of decomposition) - Roles of decomposers: Nutrient recycling and Respiration - Decomposer activity EXOGENIC PROCESSES: It includes depends on: geological phenomena and processes that - climate originate externally to the Earth's surface. - soil moisture conditions: They are directly related to the Hot, wet preference of atmosphere, hydrosphere, biosphere, and decomposers lithosphere. - Micro-environmental factors Weathering and Erosion 3. The Space Component Weathering: Processes at or near Earth’ s - Soil pores: filled with air surface that cause rocks and minerals to and/or water break down. a. Soil Air - The breaking down and changing of rocks as a result of exposure to the environment Types of Weathering: - Mechanical weathering: Processes that break a rock or mineral into smaller pieces without b. Soil Water: Precipitation. altering its composition. Ingredient and a catalyst for - Chemical Weathering: Processes chemical reaction that sustain life that change the chemical and influence soil development. composition of rocks and minerals c. Soil Profile: Soil horizon is a layer as a result of exposure to different generally parallel to the soil crust, substances. whose physical characteristics Processes and Agents of Mechanical Ex: Limestone Cave Feature Weathering 2. Oxidation: Minerals may combine 1. Frost Wedging: cracking of rock with oxygen to form new minerals mass by the expansion of water as that are not as hard as the original it freezes in crevices and cracks. rock. For example, the Expanding ice at a temperature of iron-containing mineral pyrite forms 7.6o C can exert a pressure on the a rusty-colored mineral called rock. limonite.Iron, aluminum, sodium 2. Thermal expansion and and copper readily react with contraction: repeated heating and oxygen. cooling of materials cause rigid 3. Hydrolysis: Minerals may substances to crack and separate. chemically combine with water to Daily heating cycle causes 30o C form new minerals. These are variation; this causes expansion generally not as hard as the pressure on the surface of the original material. Process where rocks that creates fracture. molecules of some substance in 3. Exfoliation: As underlying rock rocks chemically combine with layers are exposed, there is less water molecules. pressure on them and they Ex: Feldspar Hydrolysis, expand. This causes the rigid Kaolinite(clay) layers to crack and sections to slide off (similar to peeling of outer - Climate: wet and warm maximizes skin layers after a sunburn). The chemical reactions expanding layers often form a - Plants and animals: living dome (unloading). organisms secrete substances that 4. Abrasion: Moving sediments or react with rock rock sections can break off pieces - Time: longer contact means from a rock surface they strike. greater change The sediments can be moved by - Mineral composition: some wind or water and the large rock minerals are more susceptible to sections by gravity. change than others 5. Root wedging/plant wedging: As - Weathering produces regolith plants such as trees send out root (“rock blanket”) which is composed systems, the fine roots find their of small rock and mineral way into cracks in the rocks. As the fragments. roots increase in size, they force - When organic matter is mixed into the rock sections apart, increasing this material it is called soil. the separation and weathering. Processes of Chemical Weathering Erosion: Process of removing Earth 1. Dissolving materials from their original sites through (dissolution)/Carbonation: Water, weathering and transport. The often containing acid from transportation of sediments that have dissolved carbon dioxide, will been broken down by the weathering dissolve minerals from a rock body process. leaving cavities in the rock. These There are 5 main agents of erosion: cavities may generate sinkholes or 1. Running Water (main agent) cave features such as stalactites 2. Glaciers and stalagmites. 3. Wind  4. Gravity B. Suspension: clay sized/colloids are 5. Man carried along with the water molecules Weathering must happen before erosion. during erosion. They are neither at the The rocks have to be broken into smaller bottom or on the top. They are suspended sediments before they can be eroded in the middle of the running water. away. C. Saltation: solid sediments are rolled There are 4 basic products of and bounces along the bottom of a river weathering that can be eroded: stream because they are denser. 1. Soils There are 5 ways that man can cause 2. Solid Sediments (boulders, erosion: cobbles, pebbles, sand, silt) 1. Forestry: When vegetation is 3. Clay Particles (not visible to your removed, without roots, the soil will eye) erode away. 4. Ions (very small electrically 2. Strip Mining: removing rock cover charged particles) to get to the resources below, You can identify which agent of erosion which causes the loose sediments transported each sediment by looking to erode away. at a few characteristics: 3. Construction: the clearing of land 1. Running Water: sediments that to build buildings/houses also have been transported through causes all loose soil to erode running water appear rounded and away. smooth and are deposited in 4. Improper Farming: not plowing sorted piles. the land at right angles to slopes 2. Glaciers: sediments that have causes soil to erode away. been transported by glaciers 5. Salting Highways: the salt is appear scratched, grooved, and washed off the road to the sides, are deposited in completely where it prevents vegetative unsorted piles, because they were growth along the sides. dropped during melting. Also, boulders can only be transported Deposition: the process where sediments by glaciers. are released/dropped by their agent of 3. Wind: sediments that have been erosion. Most deposition happens in transported by wind appear pitted standing/still bodies of water (random holes) and frosted (glazed (oceans/lakes). Deposition is caused by look) and are deposited in sorted the slowing down (loss of kinetic energy) piles. Only very small particles can of the agent of erosion. be transported by wind. 4. Gravity: sediments that are WEATHERING, EROSION and transported by gravity are found in DEPOSITION piles at the bottom of cliffs or steep Weathering: the breakdown of rocks into slopes. They appear angular and smaller pieces, called sediments. unsorted. Erosion: the process where the Running water can transport sediment sediments are transported by wind, in three ways: gravity, glaciers, man, and running water. A. Solution: the smallest particles of Deposition: the process whereby these weathering are dissolved in water, and sediments are released by their they are transported in a solution. transporting MASS WASTING (mass movement): a surface. A rapid flow of snow down a hill collective term for downslope transport of or mountainside. surface materials in direct response to Topple: Forward rotations out of the slope gravity of a soil on rock mass - Can happen almost anywhere Spread: Lateral extension and fracturing - Commonly associated with other of a coherent mass due to the plastic flow events (heavy rainfall or of underlying material. May result from earthquakes, for example) and are liquefaction or flow of the softer material. therefore under-reported - Movements can either be Risk factors to increase likelihood of catastrophic (slope failure) or slow mass movement - and steady (creep) - The rate of the mass movement 1. Gravity: hill slopes (on top of a hill, can be increased by various on the slope, or at the bottom of a erosive agents (especially water) hill), modified slopes (road cut, cut flat area to build on, coastal Slide: A descending rock mass remaining erosion, etc.) are more vulnerable coherent, moving along one well- defined 2. Water: risk is higher when ground surface. is saturated and/or during heavy Flow: The debris is moving downslope as rains a viscous fluid. 3. Earth Materials: loose soils Fall: Earth’s material plummeting (particularly clay-rich) or fractured downward freely through air. Occurs when rock, and old landslides pose material free falls or bounces down a cliff. greater risk - Rockfall is a form of mass 4. Triggering Events: heavy rain movement or mass wasting in during storms, rain after big storms which pieces of rock travel or fires, earthquakes (when ground downward through some is saturated.) combination of falling, bouncing, and rolling after they are initially LAYERS OF THE EARTH separated from the slope. - Most common type of fall Crust Creep: A slow migration of particles to - Relatively thin with rocky outer skin successively lower elevations. - Two types: Continental crust & - Downslope movement of soil and Oceanic crust (oceanic crust is uppermost bedrock compositionally more similar to - Creep happens at too slow of a Earth’s mantle) rate to observe directly - 3 km thick at the oceanic ridges, - Instead, creep can be identified by 70 km thick in mountainous areas. its effect on objects - Major abundant elements: oxygen, Slump: Sliding of coherent rock material silicon, aluminum, iron, calcium, along curved surfaces. Results due to sodium, potassium, and undercutting of the mountain’s base magnesium Avalanche: A type of mass movement in - Its base or boundary is called the which much of the involved material is Mohorovicic discontinuity (Moho). pulverized and then flows rapidly as an Mantle airborne density current along Earth’s - 2, 885 km thick beneath the crust.  - Largest bulk (82% volume, 68% - made up of two layers separated mass) by Bullen discontinuity. - Most rocks in it are made up of - 2270 km thick. peridotite (silicon, oxygen, iron, - temperature reaches up to and magnesium) approximately 4,000 to 5,000 - Material is hot and dense and degrees celsius. moves as semi-solid rock. - movement of the liquid within the - Flows at a slow rate. outer core generates Earth’s - Behaves like a solid when seismic magnetic field (Dynamo Effect). waves pass. - The inner core is a solid dense - Lithosphere (“sphere of rock”): metallic sphere with a radius of consists of the crust and 1216 kilometers and is the hottest uppermost mantle and forms portion of the Earth reaching 5,000 Earth’s relatively cool, rigid outer to 7,000 degrees celsius. Despite shell. its higher temperature, the inner - Asthenosphere (“weak sphere”): core is solid, not molten like the is a relatively soft, weak layer outer core, due to the immense composed of the lower part of the pressures that exist at the center of upper mantle. Its our planet. temperature-pressure conditions facilitate melting of rocks and Magma therefore thought to float or move - molten rock underground and about on the slowly flowing molten rock erupted at the Earth’s asthenosphere, creating the surface. Most magma originates in movement of tectonic plates. Earth’s uppermost mantle. The - Mesosphere (“rigid layer”): is greatest quantities are produced at found below the asthenosphere divergent plate boundaries, in characterized by having a high association with seafloor temperature located 600 km below spreading, with lesser amounts the Earth. forming at subduction zones, - Gutenberg-Weichert where oceanic lithosphere discontinuity (transition zone): descends into the mantle. the interval between 410 km (255 - Melting due to decompression miles) and 660 km deep, within this (Decompression Melting): The zone, several changes take place decrease in pressure affecting a in the character of the minerals hot mantle rock at a constant making up mantle peridotite. temperature permits melting Core forming magma. This process of - consist mainly of iron combined hot mantle rock rising to shallower with an unknown quantity of nickel, depths in the Earth occurs in as well as minor amounts of mantle plumes, beneath rifts and oxygen, silicon, and beneath mid-ocean ridges. sulfur—elements that readily form - Melting due to the addition of compounds with iron. volatiles (Flux Melting): Happens - located in the center of the Earth when volatile compounds (ones itself and is the hottest and that easily exist in gaseous forms) densest part of the Earth. such as water (H2O) and carbon dioxide (CO2) seep into solid, very  hot, rock. These volatile gases 3. Due to the extreme pressure and decrease the rock’s melting point heat in the mantle the solid and they help break the chemical tectonic plate melts and rock will bonds in the rock to allow melting. completely melt and forms what is (Note: Volatiles are compounds known as magma. with low boiling points) 4. This molten material rises due to - Melting due to heat transfer many reasons such as releasing of (Heat Transfer Melting): A rising heat and buoyancy tries to escape magma from the mantle brings and makes its way through the heat with it and transfers heat to crust. their surrounding rocks at Hot Spot: A hot spot is fed by a region shallower depths which may melt. deep within the Earth’s mantle from which The heat that magma brings with it heat rises through the process of may increase the temperature of convection. This heat facilitates the the surrounding crust sufficiently to melting of rock at the base of the cause it to melt. lithosphere, where the brittle, upper portion of the mantle meets the Earth’s ENDOGENIC PROCESS: VOLCANISM crust.The melted rock, known as magma, often pushes through cracks in the crust to Volcanism: refers to the extrusion of rock form volcanoes. matter from Earth’s subsurface to the Location of Volcanoes: Most volcanoes exterior and the creation of surface terrain are found near subduction zones and such as volcanoes. mid-ocean ridges. Volcano: a rupture in the crust of a - Some volcanoes are located in planetary-mass object, such as Earth, that remote places like in the middle of allows hot magma, volcanic ash, and the Pacific plate (Hawaii), gases to escape from a magma chamber thousands of kilometers away from below the surface. the nearest plate boundary. Formation of a Volcano Parts of a Volcano Tectonic Plate Theory: Formation of a volcano may take place on either of the occasion irrespective of the direction of the movement of the tectonics plates 1. Tectonic plates are on a collision course and when such an event occurs due to extreme pressure one of the plate’s slides over the other. 2. One of the tectonic plates is forced into the mantle and other rise above the other one  1. Magma Chamber: a large pool of - Steep conical hill; mostly liquid rock found beneath the composed of basalt surface of the Earth - Low viscous magma; hot and soft 2. Bedrock - Gas expands and forms bubble in 3. Conduit: An underground passage lava; high levels where magma travels through. - Short lifespan (if active) 4. Base: lowest part or the supporting - Eruption style: mildly explosive, layer of the volcano erupt lava from a breach inside or 5. Sill: A flat piece of rock formed base of volcano, gas filled lava when magma hardens in a crack in cools to become cinders a volcano. - Paricutin (mexico), Sunset crater 6. Dike: barrier or obstacle in a Shield Volcano volcano - Broad, gently sloping landform; 7. Ash built by many layers of viscous 8. Flank: The side of a volcano. lava flows 9. Lava - Slopes are between 2 and 10 10. Throat: Entrance of a volcano. The degrees from the horizontal, part of the conduit that ejects lava producing a flattened dome or and volcanic ash. shield 11. Summit: Highest point; apex - Hot, low viscosity (running) 12. Parasitic cone: A small magma, fastmoving cone-shaped volcano formed by an - Low level gas can escape from accumulation of volcanic debris. magma 13. Lava Flow - Eruption style: relatively 14. Vent: An opening in Earth's non-violent which can be attributed surface through which volcanic to the fluidity (less viscous) of the materials escape. basalt lava ejected from the vent 15. Crater: Mouth of a volcano - - Mauna Loa of Hawaii and Kilauea surrounds a volcanic vent. of Hawaii 16. Ash Cloud Composite Volcano - Large, nearly perfect sloped Type of Volcanoes structure Based on its activity: - Its conduit system contains a Active: has erupted since the last ice age central or clustered group of vents. (i.e., in the past ~10,000 years). Also, at - Symmetrical slopes, intermediate the present time it is expected to erupt or steepness is erupting already. - Magma is slightly cooler, thick and Dormant: an active volcano that is not sticky, very viscous erupting, but supposed to erupt again; - High level gas pressure from gas hasn't had an eruption for a very long time bubbles is trying to escape Extinct: has not had an eruption for at - Eruption style:explosive; least 10,000 years and is not expected to violent(lava flows,lahar,pyroclastic erupt again in a comparable time scale of flows) the future. - Mt.Fuji in Japan, Mt. Shasta in Based on its shape: California, MayonVolcano, Mt. Cinder Volcano Pinatubo and Mt. Kanlaon - Simplest type Volcanic Eruption and begins to harden, its ability to flow 1. Confining pressure (exerted by decreases and eventually stops overlying material) decreases as a Composition of magma: magma with result of decompression from the high silica content are more viscous than magma rising from a higher those with low silica content. pressure point to a lower pressure Amount of gas contained in magma: point. gas (mainly water vapor) dissolved in 2. Vapor pressure (pressure exerted magma tends to increase the magma’s onto solid or liquid to turn them into ability to flow. gas) increases because the magma cools which initiates a Materials extruded during volcanic crystallization process that eruption: enriches the magma content. PYROCLASTIC MATERIALS (TEPHRA): 3. When the vapor pressure becomes another name for a cloud of ash, lava greater than the confining fragments carried through the air, and pressure, magma rises toward the vapor, such a flow is usually very hot and surface where the pressure is moves rapidly due to buoyancy provided lower by the vapors. Note: Ash is the smallest 4. The dissolved gas is allowed to fragment that volcano extrude expand and forms small gas bubbles called vesicles in the magma. 5. These vesicles make the magma less dense than the surrounding rock which may allow the magma to move upward. 6. As it gets closer to the surface, the size and the number of vesicles increases and exceeds the melting volume in the magma producing a magma foam that can lead to an explosive eruption. Nature of Eruption Style: The viscosity of a lava determines how easily gas escapes in the atmosphere - the more viscous the lava and the greater the volume of gas is trying to escape, the more violent and dangerous a volcanic eruption is. (Viscosity is a measure of a fluid’s resistance to flow) Three factors that affect the viscosity of the lava: - Blocks are fragments broken from Magma temperature: the viscosity of solid rock, while bombs are molten magma decreases with temperature.The when ejected. higher the temperature of magma is, the lower its viscosity. As lava flows, it cools LAVA FLOW: streams of molten rock that pour or ooze from an erupting vent. Lava is erupted during either non-explosive activity or explosive lava fountains. - PAHOEHOE FLOW: has a shiny, smooth, glassy surface. It tends to be more fluid (lower viscosity), hence flows more quickly and produces thinner flows (typically 1-3 m). Hardened crust along and wrinkling into ropy surface - AA FLOW: a rubbly flow, with a molten core, with higher viscosity (but same composition) which, therefore, tends to move more slowly and produce thicker flows (typically 3- 20 m). -