These are not visible to the unaided eye. In an introductory level lab it is impossible for us to determine these two aspects of a mineral. Using the following picture draw a box around the area that is shown in Figure 2. There will be another Chicxulub-size impact event, he said. What process do you think formed Reuyl crater (marked B on Figure 11.5)? ( ) + 2 3 i r M N g h p q r s t But Earth has several things the moon doesnt an atmosphere and liquid water that cause erosion. Fig. Quartzite is composed of quartz sand grains. As mentioned above, the composition of most igneous rocks can be identified using this system, formally known as the Color Index. For instance, the famous Chicxulub crater in Yucatan, Mexico, is thought to be the site of the meteor impact that instigated the K-T event, which wiped out the dinosaurs in a mass extinction that affected much of life on Earth. Justify your answer. The bottom line is, everything that happened on the moon happened on the Earth, said David Kring, crater expert and team leader for Center for Lunar Science and Exploration. 4. Melosh, H.J. 5. Hb```,6 u!b`0pT 9, ",8FRc g3g86y~D#*}So ". 16. Figs. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Martian shield volcano, Olympus Mons. 10. Shock waves behave like other waves: they can interfere and they may be reflected and refracted. 1 0 obj Sedimentary rocks are rocks composed of sediment. Earth Rocks Introduction Minerals are defined as naturally occurring, inorganic, solids with a definite chemical composition and a regular, internal crystalline structure. The large circular dark areas in the image are impact basins, created as huge impactors struck the Moon. Explain why you believe the way you do. 10 12 exemplify typical terrestrial structures. Impact basins are very large impact structures that are more than 300 kilometers (185 miles) in diameter. 18. Texture of sedimentary rocks in this lab will be taken to indicate origin or type of sediment found in the rock. These are not commonly tested for in an introductory lab. Igneous Rock Identification ChartCOMPOSITION \\\\\\\\\\\\\\\\ TEXTURE\\\\\\\FelsicIntermediateMaficUltramaficPegmatiticGranite PegmatiteDiorite PegmatiteGabbro PegmatitePhaneriticGraniteDioriteGabbroDuniteAphaniticRhyoliteAndesiteBasaltPorphyriticRhyoliteAndesiteBasaltGlassyObsidianBasaltic GlassVesicularPumiceScoriaPyroclasticVolcanic Tuff Composition of igneous rocks is properly identified by determination of the rocks chemical composition. 19). The edges of these larger craters also may slump, creating terraces that step down into the crater. On a world with an atmosphere, the object is heated by friction with the blanket of air. As a result, there are only around 160 known impact craters in existence today (though there are surely more that haven't been discovered). What are craters? In concurrence with this result, the crater age . Such outbursts can be violent enough that once the eruption is over, the volcano collapses in on its empty vacant magma chamber and forms a caldera, or volcanic crater. Posted by: Soderman/NLSI Staff xTO@~^^g!$(01D=l{t 20. The excavation stage ends on release from shock and when the displacements by excavation cavity formation and downwards/sideward compression reach an end. The Vredefort impact crater, about 100 kilometers (60 miles) from Johannesburg, South Africa, was formed just a little over 2 billion years ago. A bowl-shaped simple crater (Wolfe Creek, Australia, 900 m diameter). : Impact cratering. What would happen if a loosely bound impactor such s this were to strike Earth? 7) will result. 4 0 obj Here is a look at the violent, battered past of the . Based on the number and morphology of craters, is this a relatively old or young region of Mars? Larger impacts also still occur, but these are much more rare. On this Wikipedia the language links are at the top of the page across from the article title. At the edges of lunar maria, there are often damaged walls of craters formed before the maria. . Explain why you believe this is so. endobj * Definitions simplified or modified from Bates, R.L. Four minerals that need to be identified are quartz, halite, gypsum and calcite. These definitions and methods are simplified. Press, Oxford, 1989. endobj The greater the mass of the impactor, the greater the size of crater. Media Policy This was obviously not the case, and so most of the Moon craters could not be meteoritic. Sediment is deposited in a number of environments of deposition, by both moving air and moving water. Ma'adim Vallis is the channel in the southeast part of the photograph, marked C. Which of the four processes do you think formed Ma'adim Vallis? (Viking MDIM Volume 4) 15. The Crater Maker should stand over their sand-filled container and hold their arm out at the height they are going to drop it. 17 0 obj <> Fig. 5. (Viking image 645A57) 6. What is the diameter of the large crater towards the bottom of the image? e. Image from the Viking Orbiter, courtesy of the Lunar and Planetary Institute. Textures are based primarily on crystal size. The Moon does not. Marble is composed of calcite and will readily react to a small drop of HCl. Lava later flowed across the low floors of the basins, giving them a darker, smoother appearance than the surrounding, brighter highlands. Spreading outwards from the point of contact, compressive shock waves are permanently reflected from the free target surface as tensile rarefaction waves of comparable intensities and, like the shock waves, are propagated downwards. The crater is about 1.2 kilometers (a little more than 0.5 miles) across and 200 meters (650 feet) deep. Planet Earth holds some of the strangest, natural tourist . 12. Impact structures are formed by a cosmic body travelling at a velocity exceeding that of sound commonly around 5 km/s impacting target rocks leading to the sudden intense spreading of shock waves. 23. Both craters are roughly 300 or so meters across; you could walk briskly across them in a couple of minutes. Three processes help Earth keep its surface crater free. Craters come in two flavors: those that aren't caused by asteroids or comets, impact craters, are formed by powerful volcanic explosions. Phyllitic foliation is composed of platy minerals that are slightly larger than those found in slaty cleavage, but generally are still too small to see with the unaided eye. | What influences the size and shape of a crater? . These craters are, however, decidedly not impact structures. Are the craters you observe older or younger than the valleys? The origins of Uluru (and Kata Tjuta) date back about 500 million years, to around the same time the Australian continent was formed. So far we have considered the impact of a solid object like a stony or iron meteorite. Through a combination of these principles, the relative ages of geologic features can be determined, and a sequence of geologic events developed. The crater was created instantly when a 50m, 150,000-ton meteor slammed into the desert about 50,000 years ago. Some water probably seeped into the ground and is frozen there today as ice, and some likely escaped into space over time. Although craters look like imprints of a giant fist smashing the ground inward, impact shock waves have the opposite effect, which planetary scientists divide into three phases. 14. Larger craters can have terraces, central peaks, and multiple rings. Scientists record the size and number of impact craters and how eroded they are to determine the ages and histories of different planetary surfaces. Ma'adim Vallis is the channel in the southeast part of the photograph, marked C. Which of the four processes do you think formed Ma'adim Vallis? The Chicxulub crater in the Yucatan peninsula, Mexico, is not visible at the surface of the seafloor. These stages are: the contact and compression stage (Fig. HVsT{! A stone-into-mud crater demonstrates the difference between it and a hypervelocity crater (Fig. The two most notable are obsidian and dunite. (Hint: the region slopes to the north.) Name _____ COSMORPHOLOGY - May 2009 Geologic landforms Purpose: By studying aerial photographs you will learn to identify different kinds of geologic features based on their different morphologies and learn the processes involved in their formation. The extreme environmental shifts caused a mass extinction of 75% of Earth's species, including the dinosaurs. Small craters often are simple bowl-shaped depressions. It is true meteorites crashing as stones from the sky at free-fall velocity may in fact produce small craters in the ground similar to mud and hailstone craters. This flow field grows with time, and the rock mass flow is directed upwards, sideward and downwards. The composition of clastic sedimentary rocks is divided into three types - clay/silt, sand and gravel. Sedimentary Rock Identification ChartTEXTUREGRAIN SIZECOMPOSITIONROCK NAMEClastic2 mmrock fragments, quartz, feldsparConglomerate1/16 - 2 mmquartz, feldsparSandstone<1/16 mmquartz, clay mineralsMudstone1/16 mmfeldspar, quartzArkoseChemicalcalciteLimestonesilica (quartz)ChertgypsumRock GypsumhaliteRock SaltBiologicorganic material, plant fragmentsBituminous Coalcalcite, shell and skeletal fragmentsCoquinacalcite with some fossilsFossiliferous Limestone Metamorphic rocks are rocks that have undergone a change from their original form due to changes in temperature, pressure or chemical alteration. Here again, the difference is obvious: In the case of cobble-into-mud or raindrop impacts the craters are not much larger than the projectile (Fig. 14. The meter scale indicates water depth. The reflected tensile stresses are insofar crucial as the tensile strength of rocks is much lower than the compressive strength. Typically, these rocks split along parallel, planar surfaces. -yM. e. The general story of an impact follows a pretty predictable process. Whereas volcanic craters arise from deep inside the planet, impact craters originate in outer space. Scratch the unknown mineral with a known hardness to determine which mineral is harder. ), 1987, Glossary of Geology. Although temperatures below freezing and low atmospheric pressures do not allow liquid water on the surface of Mars today, erosion processes involving running water were important on Mars in the past. Barringer Crater (Meteor Crater) in Arizona, United States, is a simple crater created when a 50-meter-wide (160-foot-wide) iron-rich meteroid struck Earth's surface about 50,000 years ago a very recent event to a geologist. 15. oqoujYm<3, \xu_-^/NiU,*&N ]L$[LDf>q@#SB9o9~-EPs lRj{u/wk\:oD $Ly What process do you think formed Reuyl crater (marked B on Figure 5)? A crater is a bowl-shaped depression, or hollowed-out area, produced by the impact of a meteorite, volcanic activity, or an explosion. 4) What process do you think formed Apollinaris Patera, marked A? 8. Very similar, but still different, therefore two different minerals. But until NASA returns to the lunar landscape, researchers must rely on shockwave simulators, mathematical models and the well-worn geological formations on Earth to estimate how and when another impact event might occur. Justify your answer. Fig. Simple craters are small bowl-shaped, smooth-walled craters (the maximum size limit depends on the planet). Impact shock waves are characterized by an instantaneous onset of extreme pressures (up to the order of megabars) and extreme temperatures (up to 10,000 degrees or more) on release of the pressure. Before focusing on this important question, we have first to clarify the meaning of the term meteorite impact crater or impact structure. Impact craters are relatively shallow, so these "dents" in Earth's rocky . On relieving of pressure, there is an elastic rebound at the crater floor now hosting a layer of brecciated rocks. How does the mass of the projectile affect the cratering process? Very large impact craters greater than 300 kilometers (185 miles) across are called impact basins. in Reuyl crater located along the dichotomy boundary (west of Apollinaris Mons ). However, impacts still occur across our solar system, but at a reduced rate. [ 11 0 R] Transcript (121 KB) Overview : Impact cratering is, arguably, the most important and fundamental geological process in the Solar System. Fig. Fig. Wind-produced features, called bright windstreaks, are associated with many craters. 6. <> We can also see an inverted channel system, possibly ponded toward the southwest. PAGE 3 PAGE 1 ! These are impact craters, each of which was formed when an asteroid or comet collided with the Moon's surface. Nrdlinger Ries. -+eh5 L*]>;ppq In the upper part, the flow field enables the rock masses to escape as ejecta from the growing excavation cavity. This means that our own planet is one of the youngest in the Solar System. They leave very characteristic features. Schistose foliation is composed of larger minerals that are visible to the unaided eye. 4. American Geological Institute, Alexandria, VA, 788 p. Igneous rocks are rocks that solidify from molten material (magma). Irregular craters -- Craters with irregular shapes or multiple impact craters formed at the same time. Chapter. 288 pp, The University of Arizona Press, Tucson, 1986. XX=S;K]3:V-j ,bxHeM?qaZ] R*Jf]x-Tfymoy{!TX&THH9C]NXg (Viking MDIM Volume 4) 13. <> A good example is diamond and graphite. Earth has weather, water, and plants. The first reason is that Earth's surface is continuously changing because we live on a geologically active planet. That means it is more likely it will cool into hexagonal chunks. This icy bedrock is potentially unstable, and some impact craters may relax or fade away to unrecognition due to water ice's volatility and weak but strongly temperature dependent rheology. The polar caps shrink during local summer and grow during local winter. rBqf]&&3|sz!g8zGci3;U%SK@~hvOg[-=A'c'Z/m~V;;Y=7V99Z}kc|O;7'1m C73C?$so/Exa2Eiu8*B,Xh${BN` d&;W;D[-"Ost"/#6N*(#wz]GU Reuyl Crater Central Peak, as seen by HiRISE. Firsoff is an impact crater in the region called Meridiani Planum in the Oxia Palus quadrangle of Mars, located at 2.66N latitude and 9.42W longitude.It is 90 km in diameter. On Earth, impact craters are harder to recognize because of weathering and erosion of its surface. Moreover, the principles of superposition and cross-cutting relations indicate that a feature which at least partly covers another feature is the younger. The Earth used to look just like that.. A peak ring crater (Clearwater West, Canada, 32 km diameter). We see that shock wave and rarefaction wave propagation are essential in the formation of a meteorite impact crater. Explain why you believe this is so. In the large 35-40 km-diameter Azuara, Spain impact structure there is stratigraphic evidence for such a nearly simultaneous excavation and collapse [click here]. 3), and the central mound in the craters shown in Fig. Fig. Justify your answer. i~4?7Z"UJmiCwbes%7Vo}bf_iK4Ev, u4J_8(Vjj#W]^`:*I23SPPEX `p-1sU?"_F4I=?^i(.i]V What happens if a comet or a very low-density, loosely bound asteroid (like Mathilde asteroid, Fig. It is located along the north border of the Snake River Plain in Idaho. Procedures and Lab Questions to be Turned In: Part 1 Olympus Mons is a shield volcano 600 km in diameter, towering 25 km above the surrounding plain. Image source: NASA. b. Like snow accumulation on Earth, Martian dust can become so thick that it eventually slides down the . What happens to the transient crater? Note the remarkable difference to the crater-projectile ratio in Fig. Then, elongated craters may be formed, and the ejecta blanket may considerably deviate from a circular symmetry. Fig. What are the different kinds of craters? The texture of an igneous rock does not refer to the roughness or smoothness of the surface. Quite a few interesting questions may remain open. This image shows the variations in the gravity field near the buried impact crater. The inner walls of the crater have collapsed to form a series of step-like terraces, and a central peak is visible in the center of the image. Plagioclase is a member of the feldspar group, but there is more than one type of plagioclase. Meteor Crater is 1.2km wide and 175m deep. Oblong craters can be created by impacts striking the surface at a very low angle. Give evidence for your answer. Suggest some ways in which the scarp around Olympus Mons might have formed. The modification stage of impact cratering. Peak ring crater Rachmaninoff on Mercury. The moons surface is riddled with craters ranging in size and structural complexity, and billions of years ago before life emerged, the Earth looked the same way. The structure of the transient crater is widely preserved, and we are left with a simple or bowl-shaped impact crater (Fig. Explain your answer. 19. endobj Halite has a hardness of 2.5 and cannot be scratched by a fingernail (unpolished fingernail). 7 0 obj Coquina and limestone are both composed of calcite. During the excavation phase, the massive shock wave causes the projectile to simultaneously melt and vaporize, spewing plumes of searing hot rock vapor miles high into the atmosphere. Justify your answer. Study with Quizlet and memorize flashcards containing terms like Where do you find the thickest ejecta?, How do you think the crater rim formed?, Where would you find most of the younger material? u u u # ( u u u u u u u u u : HNRT 227 Laboratory Experiment #8 with Ms. Crowell FALL 2015 The Rocks of Earth and the Surface of Mars Purpose: To understand the rocks of terrestrial planets and how they are formed, and to interpret and analyze the surface of planets and what that teaches us about the conditions that exist today and may have existed eons ago. Dunite is composed almost entirely of the mineral olivine which usually contains both iron and magnesium. It measures 85.9 kilometers in diameter and was named after Dirk Reuyl , a Dutch-American physicist and astronomer (1906-1972) who made astronomical measurements of the diameter of Mars in the 1940s. Aeolian (wind) activity is also a continuing process of erosion. Slaty cleavage is composed of platy minerals that are too small to see. !dKG>$D1vAn Ey kde/5RehK;(V+SP;6$:wr7s]0 qh@3rFWTkiuZuC1:e`Di*{"Ge[mIGl e `GRqu]MVte4O.)XPN!QgL!eQ!7*hM,5n7OS@yoY.B>f6>x>/RNR84l,Q/b&^RA,`?l'&)sH,s@+xL:|F+08l7lF4)2BYcJOo!!g3+Ct B |2x G.eG 6`:qTC+K\dI,h^&Q!dZ 7b1UxrxU_60cPYTPOX4RExd-w9+ X'SdFht'~Y=3sQf>\B5y[s{pq],1lbl>{|>?wDxLK#2'UF*$QtiQV9C9MBfKQGR"'#6x T^!mx{8w'IN^p_R ,0IRf2/k-l^cX;;uD+ The diameter of the each miniature craters is 5 10 mm. endobj Download Planetary_Geology PDF for free. Cooling of the magma can occur beneath the surface (plutonic) or on the surface (volcanic). When a meteor makes it through Earths atmosphere without burning up, it strikes the ground faster than the speed of sound. 4). What happens when an impactor hits? In the following, these three stages are illustrated and described in a somewhat simplified manner. 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