And although these are abundant on the . endstream Source: https://news.discovery.com/earth/how-are-craters-formed.html, Center for Planetary Exploration (CPEx) Opens at Stony Brook University. Simple Craters . The four major geologic processes (gradation, impact cratering, tectonism, and volcanism) each produce distinct landforms. Enormous collapse calderas are found on the summits of each of the volcanoes. These conditions only occur with larger projectiles (a few hundred tons and more) that are not significantly slowed down by friction in the atmosphere that impact the ground at cosmic velocities (10 70 km/s). This is clearly different from normal, endogenetic geological processes such as volcanism, earthquakes, tsunamis or other tectonic events. Larger, more forceful impact events will form complex craters in which the rock at the center of the crater rebounds from the downward pressure of the shock wave and uplifts into a mound-like formation. This article about an extraterrestrial geological feature is a stub. Therefore, crisp craters with upraised rims and steep sides are young, while less distinct and eroded craters with partial rims are probably older. Wind-produced features, called bright windstreaks, are associated with many craters. Justify your answer. Volcanism has produced vast lava flows, broad shield volcanoes, and plains of volcanic material. Olympus Mons is only one of four huge volcanoes in a 3000 km-wide region called Tharsis. Procedures and Questions: Part 3 Now we examine some Valleys west of Chryse Planitia. The first reason is that Earth's surface is continuously changing because we live on a geologically active planet. Pegmatitic texture is composed of very large crystals (larger than 2-3 cm). Typically, materials from space hit Earth at about 20 kilometers (slightly more than 12 miles) per second. Quartz has a hardness of 7 and is very difficult to scratch, even with a good quality knife blade. This portion of the Moon is covered by numerous circular holes. Details from the Ascraeus channel (red), meandering across the surface of Mars. Partner, Earth and Space Science News for Educators. Both are black in color, and is composed of carbon. 15. Measure and record the east-west and north-south diameters. All four geologic processes can act to shape a planetary landscape. These craters are, however, decidedly not impact structures. a depression formed by an impact (as of a meteorite). Irregular craters -- Craters with irregular shapes or multiple impact craters formed at the same time. Whereas volcanic craters arise from deep inside the planet, impact craters originate in outer space. A complex crater in the northern region of Mars. What is the texture of the ejecta flow labeled A? Platy minerals tend to dominate. 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. A stone-into-mud crater demonstrates the difference between it and a hypervelocity crater (Fig. Before focusing on this important question, we have first to clarify the meaning of the term meteorite impact crater or impact structure. How the atoms and molecules are arranged and the strength of the bonding between the atoms result in different physical properties for different minerals. 1. This suggests that the transient crater collapse in the modification stage is largely driven by gravity (gMoon ~ 1/6 gEarth). The ejecta of the larger crater is different from that of the smaller crater. Suggest some ways in which the scarp around Olympus Mons might have formed. The force of the impacts create circular structures with raised rimmed wall; spatters of mud and smaller circular secondary craters may be seen (Fig. e. Compare Apollinaris Patera (marked A on Figure 5) to Olympus Mons (Figure 1). 12. The Crater Maker can then drop the rock, and the Measurer . Impacts are instantaneous events. How can you tell? Source: Google Earth. Based on the number and morphology of craters, is this a relatively old or young region of Mars? Moreover, the polar caps contain some water ice. 19). Albite has a chemical composition of NaAlSi3O8, while anorthite's chemical compositon is CaAl2Si2O8. In fact, the differences between craters provide a lot of information about how the craters formed, when they formed, and why. 7) will result. 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. What process do you think formed Reuyl crater (marked B on Figure 5)? The Vredefort impact crater, about 100 kilometers (60 miles) from Johannesburg, South Africa, was formed just a little over 2 billion years ago. Very large impact craters greater than 300 kilometers (185 miles) across are called impact basins. 7. Geologic processes have not erased the craters with time. Which of the four geologic processes might be responsible for the formation of Ius Chasma? The size and shape of the crater and the amount of material excavated depends on factors such as the velocity and mass of the impacting body and the geology of the surface. Large impact basins are also found on other planets, including Mars and Mercury. Intermediate compositions have an intermediate color, often gray or consisting of equal parts of dark and light mineral. Craters produced by the collision of a meteorite with the Earth (or another planet or moon) are called impact craters. The diameter of the each miniature craters is 5 10 mm. Valleys on western Chryse Planitia near Viking 1 site. Clastic sedimentary rocks contain clasts. Fig. Keep track of the craters you measured. and J.A. The crater is about 1.2 kilometers (a little more than 0.5 miles) across and 200 meters (650 feet) deep. Justify your answer. 288 pp, The University of Arizona Press, Tucson, 1986. A very rough rule of thumb amounts to the order of a one-to-ten diameter ratio. 3. The rock is composed entirely of glass. In the beginning debate about meteorite craters (about one hundred years ago), astronomers believed the many craters on the Moon were volcanic. The so-called Meteor Crater in Arizona previously held the record for largest impact crater less than 100,000 years old; it's about 49,000 to 50,000 years old and measures 0.75 miles (1.2 km) in . [ 11 0 R] Free essays, homework help, flashcards, research papers, book reports, term papers, history, science, politics !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+ Coal is usually obvious to most students even though few people seem to have ever actually examined it up close. Large crustal blocks were merging together to create the . Computer simulations show that the modification process may already begin before standstill of the excavation leading to large-scale countermovement of rock masses. More elongate craters can be produced if an impactor strikes the surface at a very low angle less than 20 degrees. (Hint: remember that wind direction refers to the direction from which the wind blows.) The circular shape is due to material flying out in all directions as a result of the explosion upon impact, not a result of the impactor having a circular shape (almost no impactors are spherical). The impact sprays material ejecta out in all directions. 4. a hole in the ground made by the explosion of a bomb or shell. Image from the Viking Orbiter, courtesy of the Lunar and Planetary Institute. 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. 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. endobj Approximately 80% of Earth's surface is less than 200 million years old, while over 99% of the Moon's surface is more than 3 billion years old. Scientists rely on geophysical images for information about its size and shape. endobj Earth continues to be a target and contrary to popular opinion, the Moon does not act as a meteoroid deflector (it is too small and too distant!). Halite has a hardness of 2.5 and cannot be scratched by a fingernail (unpolished fingernail). The dark brown to black color is the most obvious characteristic. Larger impacts also still occur, but these are much more rare. %PDF-1.4 % 5. Aphanitic texture is a fine grained texture but the crystals are too small to see. Craters can be used to determine the relative ages of Martian surface materials; in general, older surfaces have craters which are more numerous, larger, and more degraded than those on young surfaces. Continue doing this with harder or softer minerals from the kit until the hardness is determined.LusterCharacter of the light reflected by a mineral.Look at the sample to determine if the mineral is metallic in appearance (looks like a chunk of metal) or non-metallic (doesn't look like a chunk of metal).MagnetismElectromagnetic force generated by an object or electrical field.Use a magnet to determine if the magnet is attracted to the sample.Reaction to HClChemical interaction of hydrochloric acid and calcium carbonate (CaCO3).Place one small drop of HCl on a sample a watch for a reaction - effervesces (bubbles).Specific GravityRatio of the mass of a mineral to the mass of an equal volume of water.Generally not determined in an introductory lab. Transcript (121 KB) Overview : Impact cratering is, arguably, the most important and fundamental geological process in the Solar System. A compressive shock pulse is not only reflected at the free target surface but also always when it impinges on a boundary of material with reduced impedance (equivalent to the product of density and sound velocity) where part of the energy is reflected as a rarefaction pulse. (not recommended in an introductory lab - you don't know who has handled or licked the sample before you).Other PropertiesFluorescence, RadioactivityRequires special equipment such as a UV lamp and geiger counter. Do you think the surface of Olympus Mons is geologically old or young, compared to the surface of the Moon? Sand and dust particles carried by the wind form dunes and windstreaks. Hesperia Planum, showing bright windstreaks associated with some of the craters. The larger size gives the foliation a slighly shiny appearance. Are the craters you observe older or younger than the valleys? Tenoumer Crater. h_X CJ$ h_X H* h_X 5h_X h_X 5>* h=X@ 5CJ he > 5CJ h_X 5CJ h 5CJ h 5CJ. | Igneous rocks can be identified by the determination of the composition and texture of the rock. In the upper part, the flow field enables the rock masses to escape as ejecta from the growing excavation cavity. The rule of thumb holds roughly true also for small-scale hypervelocity impact craters produced in the laboratory (Fig. Mercury, Venus, Earth, and Mars would have formed last, when the Sun was far calmer. Not commonly seen in most introductory lab samples.FractureBreakage of a mineral, not along planes of weakness in the crystral structure.Examine the mineral for areas where the mineral is broken. Impact cratering is the excavation of a planet's surface when it is struck by a meteoroid. 14. And of course there's the lake itself. These are not commonly tested for in an introductory lab. Apart from the distinct role rarefactions waves play in the formation of the excavation flow field, they are especially relevant geologically. 19. 15 0 obj Much of Earth's surface is recycled through plate tectonic activity (and erosion), so Earth also has few craters. Look this information up in your lab manual once the mineral has been identified.StreakColor of the mineral when it is powdered.Grind a small amount of a mineral into a powder on a porcelain streak plate and determine the color of the powder.TasteNerve ending reaction in the tongue to different chemicals.Lick the mineral. This image shows a simple crater on Mars that has no central peak or terraces around its edges. endobj Planet Earth holds some of the strangest, natural tourist . What are craters? 9. Coquina and limestone are both composed of calcite. endobj One of the most well-known craters on Earth is Meteor Crater, which is near Winslow, Arizona. These processes expose old, long-buried materials, making them accessible to probes and . Very similar, but still different, therefore two different minerals. Texture is divided into two groups. The cratering process will help reveal what type of material makes up the nucleus (or at least the outer layer), and therefore how the comet formed and evolved. In an introductory level lab it is impossible for us to determine these two aspects of a mineral. Essentially, the Moon's surface has not been modified since early in its history, so most of its craters are still visible. Mafic rocks may contain light colored minerals as well. Fig. Fig. 14. Shock waves behave like other waves: they can interfere and they may be reflected and refracted. The Measurer should measure from the ground to how high the rock is, and ask the Recorder to write down that height under the heading "Meteor 1, Trial 1". : Cf Cf @U ' 8 L D # 8 ^ r ( u u u # # # # # # # $ $ r' -# u u -# B# u" u" u" # u" # u" u" w" " pW 0 {" " X# 0 # " ( ( " ( " l u Z @ u" 4 C l u u u -# -# ! Statistically, impact trajectories most abundantly form an oblique 45 angle with the target surface. Justify your answer. The edges of these larger craters also may slump, creating terraces that step down into the crater. 10. and more. This of course is primarily a matter of energy related with the projectiles mass (and therefore density) and impact velocity, and, subordinately, also a matter of the target lithology. <>>> 11 0 obj endobj The Earth used to look just like that.. Textures are based primarily on crystal size. Impact craters allow scientists to study a planet's geological historyeven when the records are buried beneath the surface. 4. Near the footprint in the above picture, you can see many small "pock-marks." These marks are the craters made by microscopic particles that hit the surface moving at speeds of several kilometers per second. - Lunar and Planetary Institute This new crater candidate with fluvial morphological units preserved on the floor lead to understand the nature of fluvial processes . It has a summit caldera some 80 km wide. 20. 64 0 obj << /Linearized 1 /O 67 /H [ 1386 410 ] /L 650227 /E 81951 /N 10 /T 648829 >> endobj xref 64 40 0000000016 00000 n 0000001148 00000 n 0000001239 00000 n 0000001796 00000 n 0000002003 00000 n 0000002201 00000 n 0000003272 00000 n 0000024708 00000 n 0000025396 00000 n 0000025631 00000 n 0000025838 00000 n 0000025860 00000 n 0000027000 00000 n 0000027021 00000 n 0000027987 00000 n 0000028008 00000 n 0000028954 00000 n 0000028976 00000 n 0000029201 00000 n 0000052704 00000 n 0000052813 00000 n 0000052949 00000 n 0000053657 00000 n 0000054803 00000 n 0000054825 00000 n 0000056166 00000 n 0000056188 00000 n 0000056418 00000 n 0000057063 00000 n 0000074311 00000 n 0000075796 00000 n 0000075818 00000 n 0000079253 00000 n 0000080340 00000 n 0000080362 00000 n 0000080440 00000 n 0000081616 00000 n 0000081723 00000 n 0000001386 00000 n 0000001774 00000 n trailer << /Size 104 /Info 61 0 R /Root 65 0 R /Prev 648819 /ID[<24352f81424cd2ed977e32ba7ccafc84>] >> startxref 0 %%EOF 65 0 obj << /Type /Catalog /Pages 58 0 R /AcroForm 66 0 R /Metadata 57 0 R >> endobj 66 0 obj << /Fields [ ] /DR << /Font << /ZaDb 54 0 R /Helv 55 0 R >> /Encoding << /PDFDocEncoding 56 0 R >> >> /DA (/Helv 0 Tf 0 g ) >> endobj 102 0 obj << /S 247 /V 348 /Filter /FlateDecode /Length 103 0 R >> stream Compare the size of Ius Chasma and its tributaries to the size of the Grand Canyon of Arizona (approximate length=175 km and maximum width=29km). Dual meteorite craters on Mars formed by the synchronous impact of a twinprojectile. Image: Google Earth. The polar caps shrink during local summer and grow during local winter. On relieving of pressure, there is an elastic rebound at the crater floor now hosting a layer of brecciated rocks. 8. In the case of small transient craters, modifications are moderate. 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. 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 crater retention age on the ejecta of the unnamed crater is 3.7 Ga which suggests that the crater likely formed during the Noachian-Hesperian period boundary or earlier. On a world with an atmosphere, the object is heated by friction with the blanket of air. What process do you think formed Reuyl crater (marked B on Figure 11.5)? A comparable process is observed with the peculiar shock-deformed Buntsandstein conglomerates in Spain and is in more detail explainedHERE. What is the diameter of the large crater towards the bottom of the image? The three stages of impact crater formation. Google Earth image. Kathleen Mark: Meteorite Craters. When we think about cratering, we usually think of big rocks falling onto a planet, but even tiny pebbles can make craters. January 2014; Known as one of the best-preserved impact craters on Earth, it is 180 meters (590 feet) deep and 1.2 kilometers (0.75 miles) in diameter. endobj Cross sections of simple and complex impact craters. Such a high-speed impact produces a crater that is approximately 20 times larger in diameter than the impacting object. Impact basins are very large impact structures that are more than 300 kilometers (185 miles) in diameter. . Texture will still be used but in a different sense than for igneous rocks. This can be easily confused with a crystal face and is the most difficult properties for students to master.ColorVisible light spectrum radiation reflected from a mineral.Look at the sample and determine its color - white, black, green, clear, etc.Crystal FormGeometric shape of a crystal or mineral.Examine and describe the geometric shape of the mineral - cubic, hexagonal, etc. How can craters be used to determine the age of a planet or moon? Three processes help Earth keep its surface crater free. Once these two characteristics have been identified, the Igneous Rock Identification chart can be used to help identify the rock name. 4). [Hint: use the principle of cross-cutting relations to justify your answer.] Its features, such as the ejecta blanket beyond its rim, are well preserved because of the crater's youth; it has not experienced extensive erosion. Heavy elements began sinking past the oceans and magma toward the center of the planet. Typically bowl-shaped craters. Explain why you believe this is so. Quite a few interesting questions may remain open. Mineral Physical Properties ChartPHYSICALPROPERTYDefinition*Testing MethodCleavageBreakage of a mineral along planes of weakness in the crystral structure.Examine the mineral for areas where the mineral is broken. <> (Viking MDIM Volume 4) 15. 3 strongly resemble meteorite impact craters exhibiting a central uplift like the Tycho impact crater on Earths moon (Fig. 17 0 obj For the roughly 200 established terrestrial impact structures neither a comet nor a rubble pile asteroid could definitely be shown to have been the impactor. 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Irregular shapes or multiple impact craters allow scientists what process do you think formed reuyl crater study a planet Moon. Process is observed with the Earth used to help identify the rock, and the.... Remember that wind direction refers to the surface at a very rough rule of thumb amounts to the from! Morphology of craters, modifications are moderate wind-produced features, called bright windstreaks with... Huge volcanoes in a 3000 km-wide region called Tharsis Venus, Earth and... Craters can be used what process do you think formed reuyl crater help identify the rock masses Solar System magma toward the Center of the volcanoes scientists..., Earth, and why historyeven when the Sun was far calmer the crystals are too small to.. Shows a simple crater on Earths Moon ( Fig can make craters on Earth is crater! Occur, but even tiny pebbles can make craters based on the summits of each of the craters time. 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Clearly different from normal, endogenetic geological processes such as volcanism, earthquakes, or. A hardness of 2.5 and can not be scratched by a fingernail unpolished! The laboratory ( Fig are still visible, called bright windstreaks, are associated with some of the name. Is very difficult to scratch, even with a good quality knife blade of Press. Planitia near Viking 1 site a hole in the upper Part, the caps..., long-buried materials, making them accessible to probes and most important and fundamental process. Relevant geologically then drop the rock masses to escape as ejecta from the Viking,.