Transcript S waves
SANTAN JHS 7 TH GR SEMESTER 1 FINAL EXAM REVIEW Mr. D. Coombs UMMM…. REMEMBER? • • • • • • What causes day & night? Which one is bigger the earth or the moon? Where does the moon get its light from? What percent of the earth is always lit by the sun? How many stars are in our solar system? How many days does it take for the Earth to revolve around the sun? • How many low and high tides on Earth every 24 hours? • is the third planet from the Sun, • -is an oblated sphere, • -rotates on its imaginary axis counterclockwise every 24 hours or 1 day, • -revolves around the sun every 365 days or 1 year. ROTATION CAUSES DAY & NIGHT • Which of these is the biggest? • • • • The moon The Earth The sun Jupiter • The moon revolves or orbits the Earth once every 29 days. • We always see the same side of the moon because the moon rotates and revolves at about the same speed. PHASES OF THE MOON SUN ON OTHER SIDE!! CERC ESSAY TOPIC ….. •Phases of the moon •Eclipses •Tides •Seasons TIDES THERE ARE 2 HIGH TIDES AND 2 LOW TIDES EVERY DAY. THERE ARE 2 SPRING TIDES AND 2 NEAP TIDES EACH MONTH! SPRING AND NEAP TIDES When Earth, the sun, and the moon are in a straight line (New or Full) a spring tide occurs. When the moon is at a right angle to the sun (1st or 3rd Quarter) , a neap tide occurs. SOLSTICE NORTHERN HEMISPHERE Winter December 21 Summer June 21 Southern Hemisphere - OPPOSITE EQUINOXES • A day lasts 12 hours and a night lasts 12 hours at all latitudes. • Equinox literally means "equal night". • Sunlight strikes the earth most directly at the equator. • This occurs twice a year. • The vernal (spring) equinox occurs March 21. • The autumnal (fall) equinox occurs September 21. End Part One STARS………. • A star is a ball of hot gas, which produces heat and light from nuclear reactions (fusion) within its core. • Stars are classified by color, temperature, size, composition, and brightness. STAR FACTS • Stars all appear to be points of light of the same size. However, many stars are the same size as the sun, which is medium-sized. •Stars vary in color and temperature. The color of a star is relative to its temperature. • The chemical composition of most stars is – 73% Hydrogen – 25% Helium – 2% other elements by mass HOW STARS ARE FORMED • Stars begin as a large cloud of gas and dust called a nebula. • Gravity pulls the particles of gas and dust causing the nebula to shrink. • A contracting cloud of gas and dust with enough mass to form a star is called a protostar. (Proto means “earliest” in Greek). • A star is born when the gas and dust become so dense and hot that nuclear fusion begins. ORION • In the Southern sky in autumn, WINTER, and spring • His head points to Polaris • Look for his belt – 3 bright stars in a straight line URSA MAJOR • Seen all year round (circumpolar) • Best seen in SPRING • The big dipper is part of Ursa Major URSA MINOR • Ursa Minor, the Little Bear, is visible in the Northern Hemisphere all year long. • Ursa Minor is mostly known for Polaris, the North Star, which may be found at the end of the handle. CYGNUS •Located in the Milky Way •Best seen in SUMMER and FALL •Follow inner cup of Big Dipper to tail of Cygnus •Daneb, the brightest star in Cygnus, is the tail! SCORPIUS • Sits low along the southern horizon • Best seen in SUMMER • Tail NOT visible to most northern latitudes CASSIOPEIA • Seen all year round (circumpolar) • Found in Milky Way • ½ year looks like an “M”; the other ½ year looks like a “W” • Why?? • Astronomers label stars within a constellation based on their apparent brightness, – brightest = alpha a, – second brightest = beta b, –… • Some of the brightest stars have actual names, like Rigel & Betelgeuse (both in the constellation Orion) How to find Pole Star Polaris Circumpolar Constellations The Circumpolar Stars Northern End Part Two Geology Final LAYERS OF THE EARTH CONVECTION CURRENTS KEY IDEAS: How do we know about the layers of the earth? Can you name the layers in order; outer to inner? Least dense to most dense? What is the lithosphere actually made of? Can you describe how convection currents form? What is the effect of convection currents on the lithosphere? WHAT IS ‘PANGEA’? EVIDENCE THAT ‘PANGEA’ WAS REAL… 1. Fossilized plants and animals found on completely different continents in “impossible” locations 2. mountain ranges and coal fields seem to ‘line up’ when continents are viewed side-by-side 3. glacial scarring (rocks formed and altered) in places that presently could not possibly have ice CONTINENTAL DRIFT V. PLATE TECTONICS 1. ‘CD’ first proposed by Alfred Wegener continents moving over time = CORRECT theory lacked a mechanism; ‘drift’ = INCORRECT 2. Plate Tectonics developed by Harry Hess and others studies of ocean floor with SONAR “Seafloor Spreading” KEY IDEAS: Can you explain or describe what ‘Pangea’ was? Who developed the notion of Pangea? Who was Harry Hess and what did he do? What are some examples of possible proof for the past existence of Pangea? Can you explain what the fossil record tells us about plate tectonics and Pangea? KNOW YOUR PLATE BOUNDARIES Divergent Convergent Transformational KEY IDEAS…. 1. What causes mid-ocean ridges? Deep ocean trenches? Volcanos? 2. What cause s rift valleys? Large continental mountain chains? 3. What is the actual longest mountain chain anywhere on earth’s crust? WHAT IS SUBDUCTION? Why does it happen? Which type of crust is denser? PLATE BOUNDARY FAULT Divergent Tension Convergent Compression Transformational Sheer FORCE Normal Reverse Strike-Slip WHAT ARE FOLDS? A geological fold occurs when one or a stack of originally flat surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Anticlines and synclines are the up and down folds that usually occur together and are caused by compressional stress. EARTHQUAKES Energy radiates out from the focus of the earthquake. The focus is the place within the Earth where the rock breaks, producing an earthquake. Energy moving outward from the focus of an earthquake travels in the form of seismic waves. The focus is the earthquake's underground point of origin or hypocenter. The epicenter is the point on the Earth’s surface that is directly above the point where an earthquake originates or focus. SEISMIC WAVES There are two types of body waves P-Waves or Primary Waves S-Waves or Secondary Waves 1. P waves arrive first. Primary, pressure waves. Similar to sound waves. Particle motion is along the direction of travel of the wave, i.e., longitudinal waves. P waves can travel through solids, liquids or gases. P-Wave Motion 1. S waves arrive second. Secondary, take twice as long Motion is perpendicular TO the direction of travel of the wave, i.e., transverse waves. S waves cannot travel well through water or dense rock Sideways motion cause lots of damage Monday before the Test S-WAVE MOTION What is a seismograph? Can you describe finding an epicenter using “triangulation”? THE RICHTER SCALE The Richter scale is a rating of the size of seismic waves as measured by a particular type of mechanical seismograph Developed in the 1930’s All over the world, geologists used this for about 50 years Electric seismographs eventually replaced the mechanical ones used in this scale Provides accurate measurements for small, nearby earthquakes Does not work for big, far ones THE MERCALLI SCALE Developed in the twentieth century to rate earthquakes according to their intensity The intensity of an earthquake is the strength of ground motion in a given place Is not a precise measurement But, the 12 steps explain the damage given to people, land surface, and buildings The same earthquake could have different Mercalli ratings because of the different amount of damage in different spots THE MOMENT MAGNITUDE SCALE Geologists use this scale today It’s a rating system that estimates the total energy released by an earthquake Can be used for any kind of earthquakes, near or far Some news reports may mention the Richter scale, but the magnitude number they quote is almost always the moment magnitude for that earthquake VOLCANOS Three internal structures: Magma chamber Pipe Vent THREE TYPES OF VOLCANOES: Composite : Violent explosions, large pyroclastic flow, often several pipes and vents; form alternating layers of lava and ash. ex Vesuvius (Pompei) Mt St Helens Mt Pinatubo Shield: Form over hot spots, fairly gentle eruptions, wide, gradual slopes; Their lava is very fluid (thin, runny) High, fairly level, broad/wide ex Kilauea, Mauna Loa, Joe’s Hill Cinder Cone: Form from OTHER volcanos (triggered usually by composites); very fast violent eruptions; eject cinders, ash and ‘bombs’, form narrow steep hills (triangles) ex Sunset Crater, Paracutin (Mexico) KEY IDEAS 1. What is a hot spot? 2. Where do most volcanos form? 3. Can you name the three main types and give a real world example of each? 4. What does subduction have to do with volcanos? WEATHERING The process that breaks down rock and other substances at the Earth’s surface Caused by: heat, cold, water, ice, oxygen, and carbon dioxide on the Earth’s surface! TYPES OF WEATHERING Mechanical (Physical) A rock is physically broken into smaller pieces Affects all the rock on the Earth’s surface Works very slowly, yet over time can eventually wear away a whole mountain CAUSED BY…… Freezing and thawing Release of pressure Plant growth Actions of animals Abrasion Be able to explain or recognize! Chemical The composition, or make up, of a rock is changed New minerals can be formed in a rock as it is broken down Holes or soft spots can be created in a rock so it breaks apart easier Caused by……….. Water Oxygen Carbon dioxide Living organisms Acid Rain Be able to explain or recognize! Key ideas 1. How was the Grand Canyon formed compared to Bryce Canyon UT? 2. Which probably occurs first…. ‘plucking’ or ‘deposition’? 3. Why is sandpaper an example of “abrasion”? TYPES OF ROCKS Sedimentary – layers/strata of sediment get compacted and ‘cemented’ Metamorphic – Heat and pressure turns any rock into a different kind by changing its mineral makeup Igneous – “Fire formed” deep within the earth; usually hardened magma ROCK CYCLE Rock Cycle……… The whole series of processes on the earth’ surface and in the crust and in the mantle that changes rocks from one kind to another Question: Can volcanic activity contribute to the rock cycle process? (YES….. Allows igneous rock to be formed and ejected to the surface) Is ‘smelting’ a part of the rock cycle ? (NO…. That’s a man made process for removing iron from iron ore to make steel) REMEMBER: Weathering - the process in which rocks and other substances on the Earth’s surface are broken down Erosion – The process in which rock particles are remove d from a location Deposition – The process in which sediment (rock particles) are laid down in a new location A ROCK ……. …. A mixture of minerals and other materials MINERALS •Minerals – parts that rocks are made of •Identified by: – Luster: the way something shines in the light, metallic or nonmetallic. – Splitting: the way a mineral breaks apart. – Streak: the color of the powder left when a mineral is rubbed along a rough white tile. – Hardness: the ability of one mineral to scratch another mineral MOHS HARDNESS SCALE…….. 1-10 #1 Very soft, powders easily #10 TALC Very hard, does not scratch DIAMOND FOSSILS Any “trace” or “evidence” of life from the past Special Types: “Trace” fossils show that any organism had BEEN in a location “Index” fossils are remains of extinct plants and animals of a KNOWN time period – helps us to see WHEN a layer of rock was deposited GEOLOGIC TIME SCALE A record of approximately WHEN major events in Earth’s history occurred A record of approximately HOW LONG AGO major life forms arose or vanished ERAS (Precambrian-Paleozoic-Mesozoic-Cenozoic) are divided up into PERIODS (example: Silurian 438 mya Jurassic 208 mya ……) Day before the test!