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地球科学Earth Science


Earth Science Earth science is the study of earth as a planet and how it interacts and relates to cetestial objects. Celestial Objects - other objects in space. The study of earth science has evolved greatly over the last 100 years or so, but only recently has become a strand of science all on its own called “earth system science”. We now know that the earth is not a srandalone planet, but it interacts with the solar system and the universe around it. Techology is becoming more advanced which means we can travel, further deeper and understand more than we ever have before. System A systemn is like a model, which can be efined as part of the universe and can b e studied separately. Closed and open system What’s the difference? In a cloed system, energy (like sunlight for example) can get in, but matter doesn’t enter or leave. In an open system the system andit’s surroundings freely exchange Both matter and energy. Planetary One of the consequences of having an assentiallt closed system is that most of our resources are finite. Energy Cycle Imcoming solar energy 100% Reflected by atmosphere6% Reflected by clouds 20% Reflected from earth’s surface 4% Absorbed by land and oceans 51% Conduction and rising air 7% Absorbed by clouds 3% Absorbed by atmosphere 16% Radiated to space from clouds and atmosphere 64% Radiated directly to space from earth Radiation absorbed by atmosphere 15% Carried to clouds and atmophere by latent heat in water vapor 23% Greenland X S R R A M G C G Origin of the universe Importance of time scales. Forces at work in the past - some changes as planet evolved. Forces at work today.

How can we measure age of the earth. How old is Earth? Biblical scholars of 19th century(Bishop Ussher) - 600 years (Started at 4004 BC) Classical Greeks - infinite - history endlessly repeats itself. Mayans believed earth recycled on a 3000 years time scale Han Chinese thought earth was recreated every 2369040 years The age we now except may change but is consistent with current theory. More recent efforts Lord Kelvin: 80 million years old - based on cooling of molten earth. Darwin: really old based on time for natural selection(biological argument) Hutton: really old based on uniformitarianism(Processes in the past taking place at rates comparable to today) (Geological argument) Earth’s age Earth is about 4.5(or 4.6) BY old. First 700 MY earth was a spinning cloud of gas, dust and planetoids. These condensed and settled to solidify into a series of planets. Since that time, geological history and evolution commenced. The Big Bang theory Currently the dominant theory First iteration proposed by Georges Lemaitre in 1927. He observed the red shift in distant nebulas and invoked relativity. Hubble found experimental evidence(1929) - galaxies are moving away from us with speeds proporetional to their distance. Theory suggested because it explains the expansion and predicets the existence of cosmic radiation. Big Bang What is it? Collapsing cloud of interstellar dust. Cloud dense and cold so collapses under its own self-gravity (cold gas has less internal pressure to counteract gravity) Once collapsed, it s immediately warms up because of release of gravitational energy during collapse All mass and energy concentrated at a geometric point ~14 or 15 BY age Beginning of space and time Expansion/cooling of universe began Protons and neutrons form Cooling initiated the formation of atoms - first mostly Hydrogen and helium(two lightest

elements.) Our solar system Most of the material in the cloud that formed our sun ended up in the sun. Some material ended up in the nebular disk around the sun.

Structure of the earth The earth is made up of 4 different layers. Each layer has it’s own properties and is unique The layer we live on the crust is the thinnest layer and the coolest. Crust Mantle outed core inner core

Atom The smallest unit of an element that retains the physical and chemical properties of that element. The small units of matter that combine in chemical reactions. Are divisible into smaller units(protons neutrons and electrons) Atom Structur Nucleus: the dense center containing nearly all of the mass of the atom. Proton: has a positive electrical charge of +1(The heaviest part of the atom) Neutron:is electrically neutral. Electron: in the surrounding cloud of moving particles, very little mass and have a negative charge of -1 Chemical Reaction Are interaction of the atoms of two or more chemical elements in certain fixed proportion that produce new chemical substances called. -chemical compounds.

Graphite and Diamond are polymorphs of the element Carbon, but Graohite is soft while diamonds are the hardest substance on Earth. Element of major abundance in earth’s Crust: H O Fe Mg Al Si P B C N F Cl S Zn Cu Ni Po Ti Ca K Mineralogy What are Minerals? Minerals are the building blocks of rocks. A naturally occurring solid crystalline substance, generally inorganic, with a specific chemical composition. Minerals are homogeneous: they can’t be divided by mechanical means into smaller component. How do crystal form? Crystallization. The growth of a solid from a gas or liquid whose constituent atoms come together in the proper chemical proportion and crystalline arrangement. Crystals begin to grow when temperature and/or pressure is lowered. Minerals has specific chemical and physical properties Chemical Properties Rock Forming Minerals Silicates - most abundant in Earth’s crust(Lithosphere), compose of oxygen and silicon. Carbonates - Composed of carbon and oxygen, using the carbonate anion in combination with calcium and magnesium. Oxides - are compounds of the oxide anion and metallic cations. Sulfides - are compounds of the sulfide anion and metallic cations. Sulfates - are compounds of the sulfate anion and metallic cations. Other chemical classes of minerals include Native elements and Halides. Hardness: a measure of the ease with which the surface of a mineral can be scratched. Cleavage: the tendency of a crystal to break along flat planar surfaces. Luster: The way in which the surface of a mineral reflect light giving it a characteristic luster. Colour. Streak: When you rub a mineral, the powder get down from the mineral. Quartz Magnetite Graphite Galena Hematite Pyrite Chalcopyrite Hornblende Biotite Muscovite Bauxite Plagioclase Feldspar Orthoclase Feldspar Halite Hacite Calcite Sulfur Gypsum Talc Kaolinite Garnet

Dynamic earth:
What is plate tectonics Earth’s lithosphere is broken into plates that more around on the asthenosphere(upper part of the mantle) Sometimes the plates move towards, away or slide past each other.

Where did it all start In 1912 a German Scientist named alfred wegener,proposed a hypothesis called continental drift. He stated that over millions of years the continents moved or drifted from one location to another. What does this mean? Wegener thought that the continents fit together like jigsaw puzzle, and he found evience to support his hypothesis: FOSSILS! How did this happen? Continental Drift - first theory - 1912 Theory of Plate Tectonics (the science behind continental Drift)did not come out until after there was more research on Earthquakes, Magnetism and the age of the rocks on the ocean floor 1950s-1960s. How was the plate tectonic theory discovered? Scientists noticed that in the rock at the bottom of the ocean, the minerals would line up in a certain direction. This direction was pointsing to the magnetic North Pole. They also noticed that that there were sections of the ocean floor that were pointing in the opposite direction! How was the Plate Tectonic Theory Discovered? Scientist also dated thee rocks on the ocean floor and found tha tthe further away the rock was from where it was formed, the older it was. Plate Boundaries What is it? It is the location between two tectonic plates. What is a tectonic plate? A tectonic plate a broken piece of the earth’s lithosphere. There are 7 primary plates on earth, and 8 secondary plates. How do we know where these boundaries are? Volcanoes and earthquakes are big clues to where the tectonic plate boundaries are. Most of the eaerthquakes and volcanoes on earth can be found at these plate tectonic boundaries, and specifically outlining the pacific Plate. This is also known as the ring of fire. Why Do Volcanoes and Earthquakes Occur Here? When a plate moves, it either pulls away from another plate or rubs against another. When either of these two processes happen a volcano can form, and an earthquake will occur. Mantle convection Convection- A process where hot material rises, cools, falls heats up and rises again. This occurs constantly indisde the earth, and especially in the mantle. As the convection currents move, they push the tectonic plates above them, which cause the plates to move as well.

What are the consequences of mantle convection? When a plate pulls apart fomr another plate it forms a rift. A rift is a space between two plates. It can happenunder the ocean, or on land. One example of a rift is the mid-atlantic ridge, which starts near antarctica and tracels up right through iceland. Pingvellir This is a place on land in iceland where the midatlantic ridge is still currently。 Subduction Zone Eruptions This is what is currently happening in South East Asia as well as the West Coast of North America. Sometimes, when a plate get subducted magma flows up to the surface and forms a volcano. Hot Spots These tend to occur in the middle of a plate. Which until reecentlu adid not make sense to volcanologists. A mantle plume forms away from plate boundaries and erupts.

Dynamic Earth Vocanoes A volcano is a rupture on the crust of a planetary-mass object, such as earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Volcano types There are different type oof volcanoes that are found here on earth.. The typ of volcano depends on the type of magma in the chamber below the cone. The higher silica content in the magma, the more explosive the volcano. The more silica, the thicker the lava flow. Shield volcanoes. -low elevation -low silica lava -Non-explosive -Continuously erupting Cinder Cone -high elevation -high silica lava -explosive -erupts less frequently. Stratovolcano -high elevation -high silica lava

-explosive -erupts fairly frequently -builds up in layers. Cinder Cones/Stratovolcanoes -mainly around the ring of fire -subduction Zones Shield Volcanoes -Hot spots -rift zones. What comes out of volcanoes? There are many difference types of materials that come from volcanoes, not just lave. Lava is the least dangerous material to come out of a volcano. Why? Lava is very slow moving, and you can usually out-walk it. Lava The type of lava that erupts from a volcano will depend on the type of volcano it is coming from. High-silica volcanoes (stratococanoes and cinder cones) will produce really thick lava. This lava does not travel far, which causes the volcano to form really steep sides. High-silica=low viscosity Why s sticky lava dangerous? Because the lava and rock get stuck at the top of the central vent, and block thee lava from exiting the volcano. This causes immense pressure to build up inside the volcano until it finally explodes. The science word for ‘sticky lava’ is less viscous lava. Viscous means slippery. Low-silica lava Volcanoes that produce lava that is low in silica will be more viscous (slippery) and therefore will flow a lot more easily. Hawaii volcanoes are known for having very low-silica lava eruptingg from their volcanoes, which makes them non-esplosive and less dangerous. What else comes out of a volcano? Ash pumice obsidian volcanic gases Can volcanoes form on other planet? Yes! There are many volcanoes on other planets, including Mercury,Mars and Venus. Venus has the most volcanoes on its surface than any other planet in our solar system oever 1600 major volcanic feature.

Venus No one has sat and counted yet, but there could be over 1000000 volcanoes on the surface of venus. Venus is different than earth though! -atmosphere is mostly CO2. -Venus show no evidence for plate tectonics. -the volcanoes on venus are only highly viscous lavas.(no ash has been found yet) Mars Venus may have the most volcanoes, but mars has the biggest! Mars has the biggest shield volcano in our solar system -olympus mons There are kess than 20 vocanoes on Mars. Mars,like venus has no signs of plate tectonics. Most scientist think mars’ volcanoes are because of two mantle hot spots, not plate tectonics.

What is an earthquake
And earthquake is the shaking of earth’s lithosphere caused by a release of energy. The ground make shake because of a volcanic eruption, a cave collapse, or even the impact of a meteortite. The cause of ost major earthquakes on Earth is due to the build up of strain along faults or near plate tectonic boundaries. What is a fault? A fault is a break in the lithosphere where movement has occurred. Elastic rebound theory The elastic rebound theory is a explanation for how energy is spread during earthquakes. As one side of the fault is moving one way, the other side is moving in th eoppsite direction. This causes strain and deformation on the lithosphere until it finally breaks apart. Once it breaks apart, is snaps back to its orginal shaoe before it was deformed. Anatomy of an earthquake Focus- the place where the earthquake actually occurs. The focus is found within the lithosphere, and can be anywhere form about 10-700km below the surface. Epicentre- the place on the surface of the earth directly above the focus. Fault- most earthquake swill occeu along fault lines or plate boundaries. Earthquake release a lot of energy, and this energy travels throughout the earth oiin the form of waves. There are 4 main types of wavess that result fromm an earthquake P Waves S Waves L Waves R Waves

P waves- primary/pressure waves. These waves move back and forth in a pattern that is parallel to the direction of travel. S waves- secondary/shear waves Theses waves move up and down in a pattern tha tis perpendicular to the direction of travel. L wave- love waves These waves move side to side in a pattern that is perpendicular ton the direction of travel. R waves- Rayleigh waves Theese waves move in a pattern that is elliptical. What is a seismograph A seismograph is an instrument used to detect and record the waves produces by earthquakes. These earthquakes could have originated cloe by, or hundreds, even thousands of kilometers away. Seismographs are used to measure the magntude of an earthquake and to help scientists locate earthquakes epicentre’s. There are more than 10000 seismograph stations around the world. How does it work? One of the most common types of seismograph uses a heavy weight attached to a base that is a anchored in bedrock. Magnitude - the amount of enregy it releases into the earth’s crust Intensity - the amount the fround shakes. Richter Scale 1-10 each increase of 1=10 fold increase in shaking.(exponential) Mercalli Scale I-XII based on the damage to buildings and observed effects. Size of earthquake For the same earthquake, its intensity will vary from place to place. Usually, it is greatest near the epicentre, and it gets smaller further away. How oftern do earthquake occur This table shows how often earthquakes of different magnitude occur, world wide. Seismic waves Scientists dis covered that not all seismic waves act in the same manner. In fact, of the two types of body waves, only one can travel through both solid and liquid matter, the other can only travel through solids. Wave movement S waves (secondary waves) can only travel through solid material, which must means that the outer core is made of liquid.

P waves (primay waves) can travel through solid and liquid material, but in the liquid material the wave gets distorted(bent). Because of the shadow zones with each type of wave movement, scientistss have discoverded what the inner layerss of Earth could be made of. Ground shaking Liquifaction When soild that has small to large amounts of water in it loses strength and stiffness in response to a stress and begins to act more like water. Extremely dangerous, can swallow cars, building. Fround displacement Flooding Fire Tsunami When the ground iss displaced in a large body o water, the resulting movement can cause large amounts of water to be displaced, which can crash onto land and be extremely devastating. Soil is aprat of the regolith that supports the growth of plants. Regolith is the layer of rock and mineral fragments that covers most of earth’s land surface Characteristics of soil Soil composition Soil has four major components: mineral matter or broken-down rock; humus which is the decayed remains of organisms; water and air. Soil texture Texture refers to the proportions of different particle sizes. Sand silt clay Soil structure Soil particles clump together to give a soil its structure Soil formation The most impotant factors in soil formation are parent material time climate, organisms, and slope. 1,parent material Residual soil, parent material is the bed room Transported soil, parent material has been carried from elsewhere and deposited 2,time Important in all geologic processes the longer a soil has been forming, the thicken it becomes . Takes 1000 years to form one inch.

3, climate Greatest effect on soil formation. 4, organisms Organisms influence the soil’s physical and chemical properties Furnish organic matter to soil 5, slope Angle steep slopes oftern have poorly developed soils Optimum slope is a flate to undulating upland surface. Soil varies in cocmposition, texture, structure and color at different depths. Soil horizons are zones or layers of soil. A soil profile is a vertical section through all the soil horizons. The A horizon is commonly know asa topsoil. The B horizon is subsoil and contains clay particles washed out from the A horizon. The C horizon si broken rocks. Glaciers A glacier is a thick ice mass that forms above the snowline over hundreds or thousands of years. The ice age was a period of time when much of the Earth was covered in glaciers. Valley Glaciers Ice masses that slowly advance down mountain valley originally occupied by streams. A stream of ice tha tflows between steep rock wasll from near the top of the mountain valley. Ice sheets Ice sheets are enormous ice masses that flow all firections form one or more centers and cover everything but the highest land. Ice sheets are sometimes called continental ice sheets because they cover large regions where the climate is extremly cold. They are huge compared to valley glacuers. They currently cover greenland and antarctica. The movement of glaciers is referred to as flow, and it happens in two ways. Plastic flow-involves movement within the ice. Basal slip-slipping and slding downward due to gravity. Budget of a Glacier The glacial budget is the balance ,or lack of balance, between accumulation at the upper. Glacial Erosion Many landscapes were changed by the widespread galciers of the recent ice age.

How glaciers erode. Plucking-lifting of rock blocks Abrasion Rock flour(pulverized rock) Striations Landforms created by glacial erosion Glaciers are responsible for a variety of erosional landscape features, such as glacial troughs, hanging valleys, cirques aretes, and horns. Glaciated valleys. A cirque is a bowl-shaped depression at the head of glacial valley. Aretes and horns. Snaking, sharp-edged ridges called aretes and sharp pyrammid-like peaks called horns project above. Type of glacial drift Galcial drift applies to all sediments of glacial origin, no matter how, where, or in what form they were deposited There are twotypes of glacial drift Till is material deposited directly by the glacier. Glaciers are responsible for a variety of depositional feature, including Moraines- layer or ridges of till. Lateral Medial End


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