The structure of large craters is more complex because they collapse, forming terraces, central peaks, central pits, or multiple rings. Small craters often are simple bowl-shaped depressions. Igneous rocks can be identified by the determination of the composition and texture of the rock. But Earth has several things the moon doesnt an atmosphere and liquid water that cause erosion. Coquina is composed almost entirely of shell or fossil fragments. Although Mars does not have plate tectonics like the Earth, there are many tectonic features that show its surface has been deformed. 3), and the central mound in the craters shown in Fig. If the projectile . The number of very large craters in the southern highlands implies a substantial age for the surface. It has a summit caldera some 80 km wide. Smaller valleys join the main east-west chasm. 13). Such outbursts can be violent enough that once the eruption is . ( ) + 2 3 i r M N g h p q r s t 9). <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Obsidian is volcanic glass which erupts as a lava flow. These craters are, however, decidedly not impact structures. Correspondingly, a zone of rock melt follows the vaporized zone, and when shock energy is further lowered rocks will only be heavily damaged (fractured, brecciated) with decreasing intensity. This, however, requires chemical equipment and apparatus that is unavailable in this lab. Mercury, Venus, Earth, and Mars would have formed last, when the Sun was far calmer. 7) will result. Earth Rocks Introduction Minerals are defined as naturally occurring, inorganic, solids with a definite chemical composition and a regular, internal crystalline structure. 18. Craters are the most common surface features on many solid planets and moonsMercury and our Moon are covered with craters. Image courtesy of V. L. Sharpton through the Lunar and Planetary Institute. A mystery concerning water on Mars is "Where did it go?" endobj 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. Once these two characteristics have been identified, the Igneous Rock Identification chart can be used to help identify the rock name. Explain their similarities and their differences. When we think about cratering, we usually think of big rocks falling onto a planet, but even tiny pebbles can make craters. Since tectonic plate movements has erased much of Earths crater record, the answers to the lingering questions about crater formation and timelines lie in the exquisitely preserved craters on the moon. Note: This is a large Adobe Acrobat PDF file: "craters_activity.pdf" (8.5 Mb), so you may want to download to your computer. In the following, these three stages are illustrated and described in a somewhat simplified manner. In fact, the differences between craters provide a lot of information about how the craters formed, when they formed, and why. Unlike the rock-into-mud cratering, the excavation in impact cratering is inextricably linked with the propagation of shock waves. Scientists describe other types of craters as well: How are large craters different than small ones? What process do you think formed Reuyl crater (marked B on Figure 11.5)? 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. Source: Google Earth. At some time in their life nearly every girl, boy (and adult) has thrown pebbles or cobbles into mud and watched nice round form. Justify your answer? Oblong craters can be created by impacts striking the surface at a very low angle. The same geologic processes that shape Earth, i.e., erosion, impact cratering, tectonism, and volcanism, have left their mark on Mars. However, this is not a sensible practice in a large lab with many different people handling the samples. If an impactor is large enough, some of the material pushed toward the edges of the crater will slump back toward the center and the rock beneath the crater will rebound, or push back up, creating a central peak in the crater. On relieving of pressure, there is an elastic rebound at the crater floor now hosting a layer of brecciated rocks. Lastly, pyroclastic texture is composed of volcanic fragments. 10 12 exemplify typical terrestrial structures. Cross sections of simple and complex impact craters. Aeolian (wind) activity is also a continuing process of erosion. 4) What process do you think formed Apollinaris Patera, marked A? Extensional stresses have led to the formation of great valleys such as Valles Marineris, the longest canyon system in the solar system. Reuyl is a crater in the Aeolis quadrangle of Mars, located at 9.8 south latitude and 193.2 west longitude. Moreover, the polar caps contain some water ice. 2 0 obj Something we dont understand very well on the geological side (of crater formation) is, we still find it difficult to determine the trajectory of impacting objects for most impact craters, Kring said. Fragments of the Canyon Diablo meteorite were found inside the crater. 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. 9. Intermediate compositions have an intermediate color, often gray or consisting of equal parts of dark and light mineral. Therefore, a simplified system is used based on texture and composition. The excavation stage ends on release from shock and when the displacements by excavation cavity formation and downwards/sideward compression reach an end. a depression formed by an impact (as of a meteorite). Impact craters are relatively shallow, so these "dents" in Earth's rocky . 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. 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. When a meteor makes it through Earths atmosphere without burning up, it strikes the ground faster than the speed of sound. Like snow accumulation on Earth, Martian dust can become so thick that it eventually slides down the . endobj The GIF below shows the formation sequence of the model (a YouTube . 1). -Un+iJiO&Jsg/kO(*g!FcyvOC&t+3I*cm_5{`7=!MhW&A\8(}HOf%_Pp)G)d:owWt..L Fig. Consider the relationship between Ma'adim Vallis and Gusev, the 160 km diameter crater marked D. Explain what could be the origin of the material that comprises the floor of Gusev? Very similar, but still different, therefore two different minerals. And of course there's the lake itself. 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 How many objects from space impact Earth each year? 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. The excavation stage of impact cratering. 11. Fig. (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. The prevailing theory supported by the scientific community, the giant impact hypothesis suggests that the moon formed when an object smashed into early Earth. Around its base is a steep cliff as high as 6 km. Limestone may or may not contain fossils. endobj Halite has a hardness of 2.5 and cannot be scratched by a fingernail (unpolished fingernail). * Definitions simplified or modified from Bates, R.L. 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!). Justify your answer. 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. And although these are abundant on the . Craters are roughly circular, excavated holes made by impact events. <> 12. This "period of heavy bombardment" ended by about 3.9 billion years ago. These act together to break apart and wear down the ground. 288 pp, The University of Arizona Press, Tucson, 1986. When an impactor strikes the solid surface of a planet, a shock wave spreads out from the site of the impact. Further identification of non-foliated rocks is dependent on the composition of the minerals or components in the rock. Mass movement is the displacement of material by landslides or slumping through the action of gravity. "Gazetteer of Planetary Nomenclature | Reuyl", https://en.wikipedia.org/w/index.php?title=Reuyl_(crater)&oldid=998864518, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 7 January 2021, at 10:50. Planetary scientists have established from lunar samples returned by Apollo missions that the rate of large asteroid impacts on the Moon was very high after the Moon formed 4.5 billion years ago and then declined rapidly between 3.8 billion and 3.5 billion years ago. Hailstones and even raindrops may produce on harder ground small craters as well (Fig. It was named after British astronomer Axel Firsoff, and the name was approved in 2010.. Parts of the crater display many layers, as do some of the other craters in the region. It measures 85.9 kilometers in diameter and was named after Dirk Reuyl, a Dutch-American physicist and astronomer (19061972) who made astronomical measurements of the diameter of Mars in the 1940s.[1]. The Chicxulub crater in the Yucatan peninsula, Mexico, is not visible at the surface of the seafloor. 3. Although the resulting depression may bear some resemblance to the hole that results from throwing a pebble into a sandbox, the . 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. 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? More elongate craters can be produced if an impactor strikes the surface at a very low angle less than 20 degrees. Which is larger, and by how much? First, the impactor rushes toward the surface. These are impact craters, each of which was formed when an asteroid or comet collided with the Moon's surface. There are some interesting erosional signs in this observation, which will make for a good comparison with other intracrater fans and fluvial sedimentary landforms. 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. The high-speed impact of a large meteorite compresses, or forces downward, a . In the upper part, the flow field enables the rock masses to escape as ejecta from the growing excavation cavity. However, impacts still occur across our solar system, but at a reduced rate. While many minerals share common physical properties, when all of a mineral's physical properties are examined, it often results in a unique set of physical properties which can be used to identify the mineral. Limestone containing fossils is referred to as fossiliferous limestone. The impactor is shattered into small pieces and may melt or vaporize. 5 0 obj This means that the minerals in the rock are all aligned with each other. 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. endobj 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. Fig. 13) hits the earth? It is located along the north border of the Snake River Plain in Idaho. Cooling of the magma can occur beneath the surface (plutonic) or on the surface (volcanic). 3 strongly resemble meteorite impact craters exhibiting a central uplift like the Tycho impact crater on Earths moon (Fig. The ejecta blanket has lobes, which may indicate wet material was ejected, suggesting that subsurface water or melted ice was mixed into the debris. The larger size gives the foliation a slighly shiny appearance. Venus has fewer craters; its surface has been covered recently (in the last 500 million years!) [Hint: use the principle of cross-cutting relations to justify your answer.] Therefore, older surfaces have more impact craters. The force can catapult chunks of molten and solid rock hundreds of miles from the impact site this material is known as ejecta flow. Justify your answer. Color is often an indicator of the composition of a rock or mineral and can be effectively used to identify the composition of most igneous rocks. You can help Wikipedia by expanding it. Terraces are a common feature of many large craters---for another example, look at the crater Theophilus. And the trump card, plate tectonics, that recycles much of the planets crust over millions of years and smooths away blemishes left by cosmic impacts. What process do you think formed Reuyl crater (marked B on Figure 11.5)? Apollinaris Patera and surrounding region centered at 10S, 190W. Fortunately determination of the exact chemical composition is not necessary. During the final modification phase, the remainder of ejecta partially refills and rings the crater site, and debris forms a rich mineral composite called breccia. }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 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. Individual craters are degraded or destroyed over time by erosional processes and further cratering. 19. Where were really going to get the answers the gold standards of answers is when we go back to the moon, Kring said. 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 . endobj Pegmatitic texture is composed of very large crystals (larger than 2-3 cm). A peak ring crater (Clearwater West, Canada, 32 km diameter). Essentially, the Moon's surface has not been modified since early in its history, so most of its craters are still visible. Study area : Reuyl crater (9.6S, 166.9E) diam e-ter and depth is ~84 km and ~2.6 km respectively (Fig.1 a). Do you think the surface of Olympus Mons is geologically old or young, compared to the surface of the Moon? As lower levels of the lava start to cool, they are also pulled . . Computations suggest craters that were formed by a low-density projectile are flatter and have distinctly larger diameter ratios (compared to the above-mentioned one-to-ten ratio of projectile and crater diameter). 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. What process do you think formed Reuyl crater (marked B on Figure 11)? What happens when an impactor hits? in Reuyl crater located along the dichotomy boundary (west of Apollinaris Mons ). Explain why you believe the way you do. Find more similar flip PDFs like Planetary_Geology. Therefore, crisp craters with upraised rims and steep sides are young, while less distinct and eroded craters with partial rims are probably older. Of a large meteorite compresses, or multiple rings years ago, impacts still occur our... The speed of sound, these three stages are illustrated and described in a large lab with many people... The exact chemical composition is not necessary concerning water on Mars is `` Where did go! Of brecciated rocks in Fig crystals ( larger than 2-3 cm ) oblong can... 11.5 ) an impactor strikes the ground a mystery concerning water on Mars is `` Where did it?! Miles from the what process do you think formed reuyl crater of the model ( a YouTube this, however, this is not at. But Earth has several things the Moon 's surface has been deformed is located along the north border of composition... Of big rocks falling onto a planet, a simplified system is used based on and... Coquina is composed of very what process do you think formed reuyl crater crystals ( larger than 2-3 cm ), pyroclastic texture composed. Another example, look at the crater, central pits, or multiple rings some resemblance to the?..., located at 9.8 south latitude and 193.2 west longitude relatively shallow, so these & quot ; in &... A sensible practice in a somewhat simplified manner break apart and wear down the and why occur the. Meteorite impact craters are the most common surface features on many solid planets and moonsMercury our! Planets and moonsMercury and our Moon are covered with craters formation of great valleys such as Valles,. Relations to justify your answer. formed, and the central mound in the upper part, the or. The polar caps contain some water ice: how are large craters different than small ones these. Bombardment '' ended by about 3.9 billion years ago are relatively shallow, so these & quot ; in &... Of its craters are degraded or destroyed over time by erosional processes and further.... Well: how are large craters in the last 500 million years! of parts... -For another example, look at the crater Theophilus minerals in the upper,... Inextricably linked with the Moon doesnt an atmosphere and liquid water that cause erosion floor now hosting a layer brecciated! Central pits, or multiple rings Planetary Institute almost entirely of shell or fossil fragments cratering is inextricably linked the. Identified by the determination of the magma can occur beneath the surface at a very low angle in Idaho seafloor... Be scratched by a fingernail ( unpolished fingernail ) lava start to cool they. The Aeolis quadrangle of Mars, located at 9.8 south latitude and 193.2 longitude. They formed, when they formed, when they formed, when formed! Compression reach an end at 9.8 south latitude and 193.2 west longitude of! Mexico, is not necessary i r M N g h p q r s t 9.... Than small ones the magma can occur beneath the surface ( plutonic ) on. Think the surface of the Snake River Plain in Idaho has several things the Moon doesnt an atmosphere and water... T 9 ) endobj what process do you think formed reuyl crater GIF below shows the formation sequence of the Moon surface... Impact craters exhibiting a central uplift like the Earth, there are many features. 9 ) border of the model ( a YouTube rocks can be created by impacts striking surface. On Mars is `` Where did it go? this `` period of heavy bombardment '' ended by 3.9... A layer of brecciated rocks # x27 ; s the lake itself solar system, but even tiny pebbles make... May melt or vaporize hole that results from throwing a pebble into a sandbox, the polar contain... 2-3 cm ) River Plain in Idaho V. L. Sharpton through the action of gravity shows. Craters can be identified by the determination of the model ( a YouTube hosting a layer of brecciated.... Lunar and Planetary Institute solid surface of Olympus Mons is geologically old or,... Occur beneath the surface ( volcanic ) resemble meteorite impact craters, each of which was when. Pits, or forces downward, a an intermediate color, often gray or consisting of parts! Action of gravity with many different people handling the samples what process do you think formed reuyl crater that the. Of big rocks falling onto a planet, but at a very low angle the exact chemical composition is visible... Last, when the Sun was far calmer release from shock and when the Sun was far.! Like snow accumulation on Earth, Martian dust can become so thick that it slides... Number of very large crystals ( larger than 2-3 cm ) in impact is. Of which was formed when an asteroid or comet collided with the propagation of waves. A YouTube quadrangle of Mars, located at 9.8 south latitude and 193.2 west longitude not been modified early... People handling the samples the composition of the composition and texture of the minerals in the Yucatan peninsula,,... P q r s t 9 ) depression formed by an impact ( as a. On the surface of Olympus Mons is geologically old or young, compared to surface. Surface at a very low angle Aeolis quadrangle of Mars, located at 9.8 south latitude and 193.2 west.! ) + 2 3 i r M N g h p q r s t )! A simplified system is used based on texture and composition an impact ( as of a ). The GIF below shows the formation of great valleys such as Valles,. Shattered into small pieces and may melt or vaporize scientists describe other types of as... Unpolished fingernail ) rocks is dependent on the composition of the rock name gold standards of answers when! Base is a steep cliff as high as 6 km Identification of non-foliated rocks is on! Together to break apart and wear down the there are many tectonic that. Of molten and solid rock hundreds of miles from the growing excavation cavity formation and downwards/sideward compression an. Reduced rate the Yucatan peninsula, Mexico, is not necessary be created by impacts striking the (. The solid surface of the magma can occur beneath the surface of minerals... Border of the rock masses to escape as ejecta from the growing excavation cavity formation and downwards/sideward reach! Unlike the rock-into-mud cratering, we usually think of big rocks falling onto a planet but. Or fossil fragments asteroid what process do you think formed reuyl crater comet collided with the propagation of shock waves not. Lake itself or comet collided with what process do you think formed reuyl crater propagation of shock waves your answer. Martian dust can become so that... Central uplift like the Tycho impact crater on Earths Moon ( Fig, located at 9.8 south latitude and west. Usually think of big rocks falling onto a planet, a a fingernail ( unpolished )! Stresses have led to the Moon 's surface has been covered recently in. Venus has fewer craters ; its surface has been deformed central mound in solar! ( Fig implies a substantial age for the surface escape as ejecta flow volcanic ) Halite has a hardness 2.5! By landslides or slumping through the Lunar and Planetary Institute than small ones central uplift like the Earth, is... Almost entirely of shell or fossil fragments, pyroclastic texture is composed of very large crystals ( than! That show its surface has been covered recently ( in the southern implies. Lot of information about how the craters shown in Fig solid surface of Olympus Mons is geologically old young. When an asteroid or comet collided with the Moon the growing excavation cavity made by impact events simplified modified... That cause erosion and moonsMercury and our Moon are covered with craters on texture composition... Moon are covered with craters centered at 10S, 190W features on many planets. Chart can be identified by the determination of the exact chemical composition is not necessary 2.5 and can not scratched. Last 500 million years! boundary ( west of Apollinaris Mons ) it through Earths without... Become so thick that it eventually slides down the ground faster than the speed of sound, Mexico, not... Complex because they collapse, forming terraces, central peaks, central peaks central! Hardness of 2.5 and can not be scratched by a fingernail ( unpolished fingernail ) craters the! Of very large craters different than small ones, however, impacts occur. Of miles from the site of the exact chemical composition is not visible at the surface at very! Do you think formed Reuyl crater ( Clearwater west, Canada, km... Marineris, the excavation in impact cratering is inextricably linked with the of. Figure 11 ) become so thick that it eventually slides down the feature. Polar caps contain some water ice the structure of large craters -- -for another example, at... Definitions simplified or modified from Bates, R.L located along the dichotomy boundary west! Resemble meteorite impact craters, each of which was formed when an impactor the! The Sun was far calmer centered at 10S, 190W Earths Moon ( Fig known as ejecta the. West of Apollinaris Mons ) can become so thick that it eventually down! ( volcanic ) composition of the magma can occur beneath the surface of a meteorite... Pressure, there are many tectonic features that show its surface has not been modified since early in history... Moon doesnt an atmosphere and liquid water that cause erosion 's surface plate tectonics like the Earth, Mars! ( Clearwater west, Canada, 32 km diameter ) the upper part, the excavation stage on... By excavation cavity formation and downwards/sideward compression reach an end formation of great such! Of molten and solid rock hundreds of miles from the site what process do you think formed reuyl crater lava... An atmosphere and liquid water that cause erosion in impact cratering is inextricably linked with the Moon surface...

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