Non-foliated textures are identified by their lack of planar character. Larger impacts also still occur, but these are much more rare. Material Type: Lab; Class: Sci Thought/Processes I; Subject: Honors Program; University: George Mason University; Term: Unknown 1989; Three processes help Earth keep its surface crater free. Study area : Reuyl crater (9.6S, 166.9E) diam e-ter and depth is ~84 km and ~2.6 km respectively (Fig.1 a). Sedimentary rocks are rocks composed of sediment. Halite is common table salt and is most easily identified by taste. Note: This is a large Adobe Acrobat PDF file: "craters_activity.pdf" (8.5 Mb), so you may want to download to your computer. 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. in Reuyl crater located along the dichotomy boundary (west of Apollinaris Mons ). Image credit: NASA. Olympus Mons is only one of four huge volcanoes in a 3000 km-wide region called Tharsis. These crater chains are formed when a comet, normally torn apart by tides, has many of its fragments collide into the planet or moon at nearly the same time. Erosion is the dominant geologic process acting on Mars today. 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. Image: Google Earth. Large (139 km-diameter) Central-peak crater Herschel on the multiple impact Saturnian moon Mimas. }v)He|/7rw9>{W9qM~Zs.|9q7_9'o2p3kie V;\UXF}w1l`p!U,9#H{wx 0 ~ endstream endobj 103 0 obj 294 endobj 67 0 obj << /Type /Page /Parent 59 0 R /Resources 68 0 R /Contents [ 75 0 R 77 0 R 79 0 R 86 0 R 88 0 R 93 0 R 96 0 R 99 0 R ] /MediaBox [ 0 0 612 792 ] /CropBox [ 0 0 612 792 ] /Rotate 0 >> endobj 68 0 obj << /ProcSet [ /PDF /Text /ImageB ] /Font << /F2 85 0 R /F3 71 0 R /F4 91 0 R /F9 69 0 R /F12 83 0 R >> /XObject << /Im9 95 0 R >> /ExtGState << /GS1 98 0 R /GS14 101 0 R >> >> endobj 69 0 obj << /Type /Font /Subtype /Type1 /Name /F9 /FirstChar 32 /LastChar 255 /Widths [ 343 384 500 686 686 975 848 250 352 352 483 686 343 392 343 579 686 686 686 686 686 689 686 686 686 686 343 343 686 686 686 595 740 781 677 660 752 550 542 842 803 324 489 758 495 983 881 887 661 887 680 616 533 778 761 1117 789 714 707 350 579 350 686 500 402 682 682 483 682 610 388 677 661 302 302 688 302 989 661 662 682 682 453 513 360 659 623 996 712 654 559 352 579 352 686 343 781 781 660 550 881 887 778 682 682 682 682 682 682 483 610 610 610 610 302 302 302 302 661 662 662 662 662 662 659 659 659 659 686 400 686 686 686 686 686 651 800 800 940 402 604 0 1026 887 0 686 0 0 686 659 0 0 0 0 0 409 410 0 940 662 595 384 686 0 686 0 0 603 603 1000 343 781 781 887 1140 1022 500 1000 628 628 372 372 686 0 654 714 194 686 354 354 679 690 686 343 338 594 1460 781 550 781 550 550 324 324 324 324 887 887 0 887 778 778 778 302 590 549 603 539 402 457 380 539 350 590 ] /Encoding /MacRomanEncoding /BaseFont /Futura-Bold /FontDescriptor 73 0 R >> endobj 70 0 obj << /Filter /FlateDecode /Length 21345 /Length1 28684 >> stream You can help Wikipedia by expanding it. 20. Scientists estimate that Earth and the other terrestrial planets are struck by, on average, five asteroids less than 2 kilometers (a little over 1 mile) across every million years. Explain why you believe this is so. Photo Policy The two most notable are obsidian and dunite. 13 0 obj The rock is composed entirely of glass. Tycho meteorite crater on the Moon. Both will react to HCl. Dark colors, such as black and dark brown, indicate a mafic or ultramafic composition. In either case, the conditions of a hypervelocity impact and propagation of shock waves are crucial for the formation of these geologically extraordinary structures. Craters are roughly circular, excavated holes made by impact events. Mars, like the Earth, has seasons. What are the different kinds of craters? Venus has fewer craters; its surface has been covered recently (in the last 500 million years!) <> Metamorphic Rock Identification ChartTEXTUREFOLIATIONCOMPOSITIONTYPEPARENT ROCKROCK NAMEFoliatedslatymicaRegionalMudstoneSlatephylliticquartz, mica, chloriteRegionalMudstonePhylliteschistosemica, quartzRegionalSlateSchistschistoseamphibole, plagioclaseRegionalBasalt or GabbroAmphibolitegneissic bandingfeldspar, mica, quartzRegionalSchistGneissNon-FoliatedcarbonContact or RegionalBituminous CoalAnthracite Coalquartz, rock fragmentsContact or RegionalConglomerateMetaconglomeratecalciteContact or RegionalLimestoneMarblequartzContact or RegionalSandstoneQuartzite Mars Surface Introduction In many ways Mars is similar to Earth. Hailstone craters. Most obsidian is felsic in composition, yet typically it will have a very dark color (dark brown to black). Igneous rocks can be identified by the determination of the composition and texture of the rock. and more. Suggest some ways in which the scarp around Olympus Mons might have formed. HYPERLINK "../Honors227/Images/10_2.jpg"Figure 2. 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. Some of this tiny debris makes it to Earth's surface and is mixed with soil and ocean sediment. Image credit: NASA. Through a combination of these principles, the relative ages of geologic features can be determined, and a sequence of geologic events developed. and J.A. 19.) Mercury, Venus, Earth, and Mars would have formed last, when the Sun was far calmer. The dark basins can be seen by the naked eye. 12. How looks an impact crater that was produced by an oblique impact? Platy minerals tend to dominate. Describe the breakage as either irregular or conchoidal (has the appearance of broken glass)HardnessResistance to scratching or abrasion.Use minerals of known hardness from the Mohs Hardness Kits. The completely unnerving possibility that such force can be delivered in such a short time may well contribute to both the lack of understanding and often disbelief many geologists hold toward cratering events. In what direction did the water flow? Thank you for your participation! (80 km diameter). 14. endobj The diameter of the each miniature craters is 5 10 mm. !#\k]k)3f}2Xyb=Np. These chunks begin to form at the top layer of the lava, which is cooling the fastest. <> Procedures and Questions: Part 5 Finally, let's examine Apollinaris Patera and surrounding region. Computing these vectors (direction and magnitude) for each point in the subsurface, a field of excavation flow with arcuate trajectories as shown in the sketch above (Fig. Felsic compositions are rich in silica (SiO2). These processes expose old, long-buried materials, making them accessible to probes and . e. 1). The extreme environmental shifts caused a mass extinction of 75% of Earth's species, including the dinosaurs. Multi-ring basin Mona Lisa on Venus. -yM. Justify your answer. Enormous collapse calderas are found on the summits of each of the volcanoes. Impacts are instantaneous events. The compression stage of crater formation involves that initial exchange of energy between the projectile and the impact area. The impact-cratering process. 17. A very rough rule of thumb amounts to the order of a one-to-ten diameter ratio. 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. The transition from simple to complex craters occurs at about 1.5 to 4 km (depending on the target rocks) final diameter for terrestrial craters and is much larger (c. 15 km) for craters on the Moon. 6) Consider the relationship between Ma'adim Vallis and Gusev, the 160 km diameter crater marked C. Fig. The same geologic processes that shape Earth, i.e., erosion, impact cratering, tectonism, and volcanism, have left their mark on Mars. 15 0 obj Mass movement is the displacement of material by landslides or slumping through the action of gravity. The image to the left is a very simple, bowl shaped crater on the Moon and is typical of small craters that have formed relatively recently. What process do you think formed Reuyl crater (marked B on Figure 5)? The ejecta of the larger crater is different from that of the smaller crater. Craters produced by the collision of a meteorite with the Earth (or another planet or moon) are called impact craters. In this way, all rock particles behind the expanding shock front are captured by both the compressive shock and the tensile rarefaction, and both combine into a vector of acceleration. The four major geologic processes (gradation, impact cratering, tectonism, and volcanism) each produce distinct landforms. Image source: NASA. Very large impact craters greater than 300 kilometers (185 miles) across are called impact basins. 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. The edges of these larger craters also may slump, creating terraces that step down into the crater. Thus, if a valley cuts through a crater, the crater must be older. Here is a look at the violent, battered past of the . 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. The Vredefort impact crater, about 100 kilometers (60 miles) from Johannesburg, South Africa, was formed just a little over 2 billion years ago. However, this is not a sensible practice in a large lab with many different people handling the samples. 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. <> For larger transient craters the modifications may take on a dramatic scale. January 2014; Describe the appearance and orientation of the windstreaks. 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. Indeed, impact craters are one of the most common geological landforms on the majority of rocky terrestrial planets, asteroids, and many of the rocky and icy moons of the inner and outer Solar System. Image from the Viking Orbiter, courtesy of the Lunar and Planetary Institute. For the following, you will use the knowledge from previous questions to identify Martian landforms and describe the geologic processes that created them. The larger size gives the foliation a slighly shiny appearance. stream More elongate craters can be produced if an impactor strikes the surface at a very low angle less than 20 degrees. 11. Unlike the rock-into-mud cratering, the excavation in impact cratering is inextricably linked with the propagation of shock waves. What process do you think formed Reuyl crater (marked B on Figure 5)? Compare Apollinaris Patera (marked A on Figure 5) to Olympus Mons (Figure 1). At the edges of lunar maria, there are often damaged walls of craters formed before the maria. Terraces are a common feature of many large craters---for another example, look at the crater Theophilus. Craters come in two flavors: those that arent caused by asteroids or comets, impact craters, are formed by powerful volcanic explosions. These volcanoes erupted repeatedly over many millions of years, growing higher with each lava flow. 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 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 GIF below shows the formation sequence of the model (a YouTube . The composition of clastic sedimentary rocks is divided into three types - clay/silt, sand and gravel. Fortunately, these two aspects determine a mineral's physical properties. HYPERLINK "../Honors227/Images/10_4.jpg"Figure 4. (a) Geomorphic map of Reuyl crater. Wind-produced features, called bright windstreaks, are associated with many craters. The shock wave fractures the rock and excavates a large cavity (much larger than the impactor). 9). Geologic processes have not erased the craters with time. Terms of Use, Copyright document.write(new Date().getFullYear()); Around its base is a steep cliff as high as 6 km. Valleys on western Chryse Planitia near Viking 1 site. The Earth used to look just like that.. Porphyritic texture is composed of crystals of two different sizes. (Hint: remember that wind direction refers to the direction from which the wind blows.) Calcite readily reacts with a small drop of HCl. 5 0 obj As mentioned above, the composition of most igneous rocks can be identified using this system, formally known as the Color Index. 10. Large impact basins are also found on other planets, including Mars and Mercury. It was declared a national monument by President Calvin Coolidge in 1924. Fig. stream Image courtesy of D. Roddy through the Lunar and Planetary Institute. Source: Google Earth. Heavy elements began sinking past the oceans and magma toward the center of the planet. Inclusion, Diversity, Equity & Accessibility (IDEA). 8. Impact Craters. The result is a "bubbly" appearance. In the following, these three stages are illustrated and described in a somewhat simplified manner. Planet Earth holds some of the strangest, natural tourist . d. Maadim Vallis is the channel in the southeast part of the photograph, marked C. Which of the four processes do you think formed Maadim Vallis? 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. Mercury has lots of craters, yet Venus has very few craters, due to its dense atmosphere (containing lots of 'heavy' gases), meaning that many meteorites burn up due to friction in the . Dual crater at the bottom of Lake Chiemsee, Bavaria (Germany) that very probably formed in the large Holocene Chiemgau impact event. The largest impact basin on the Moon is 2500 kilometers (1550 miles) in diameter and more than 12 kilometers (7 miles) deep. The impact sprays material ejecta out in all directions. As lower levels of the lava start to cool, they are also pulled . The Chicxulub crater in the Yucatan peninsula, Mexico, is not visible at the surface of the seafloor. Coquina and limestone are both composed of calcite. The same chemical composition, but two different crystalline structures - therefore, two different minerals. (Viking MDIM mosaic 211-5360) 1. In concurrence with this result, the crater age . <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>

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