The Crater Maker can then drop the rock, and the Measurer . PAGE 3
PAGE 1
! 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. 288 pp, The University of Arizona Press, Tucson, 1986. Craters most often are circular. Foliated textures show four types of foliation. April 8, 2015. 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. 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. 8. Erosion is the dominant geologic process acting on Mars today. As mentioned above, the composition of most igneous rocks can be identified using this system, formally known as the Color Index. 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. Scientists record the size and number of impact craters and how eroded they are to determine the ages and histories of different planetary surfaces. Therefore, older surfaces have more impact craters. | <>
17. crater: [noun] the bowl-shaped depression around the orifice of a volcano. A peak ring crater (Clearwater West, Canada, 32 km diameter). Few, if any, crystals will be visible. Fig. Tycho meteorite crater on the Moon. oqoujYm<3, \xu_-^/NiU,*&N
]L$[LDf>q@#SB9o9~-EPs lRj{u/wk\:oD $Ly Go to Analyze-Label Selection, and the crater line you just . Dual crater at the bottom of Lake Chiemsee, Bavaria (Germany) that very probably formed in the large Holocene Chiemgau impact event. Albite and anorthite are two examples. 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. How scientists solved the riddle of these mysterious landforms. endobj
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These definitions and methods are simplified. American Geological Institute, Alexandria, VA, 788 p.
Igneous rocks are rocks that solidify from molten material (magma). 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. Glassy texture is the most readily recognized. Lastly, pyroclastic texture is composed of volcanic fragments. !#\k]k)3f}2Xyb=Np. Mars, like the Earth, has seasons. 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!). Context Image. <>
Justify your answer. 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. Photo Policy The Moon does not. 10 0 obj
HYPERLINK "../Honors227/Images/10_5.jpg"Figure 5. On relieving of pressure, there is an elastic rebound at the crater floor now hosting a layer of brecciated rocks. 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? 2. Some water probably seeped into the ground and is frozen there today as ice, and some likely escaped into space over time. (b) Contour map derived from the MOLA 463m/pixel DTM, with the . The Earth used to look just like that.. Some of this tiny debris makes it to Earth's surface and is mixed with soil and ocean sediment. Essentially, the Moon's surface has not been modified since early in its history, so most of its craters are still visible. These fragments or clasts can be very fine (ash) or coarse (lapilli) or very coarse (bombs and blocks). In the upper part, the flow field enables the rock masses to escape as ejecta from the growing excavation cavity. %PDF-1.5
Coquina is composed almost entirely of shell or fossil fragments. The modification stage of impact cratering. A central-uplift (central peak) crater (Gow, Canada, 4 km diameter). Image credit: NASA. The impactor is shattered into small pieces and may melt or vaporize. Impact Craters. This crater is about 20 kilometers (12 miles) across and has a large central peak and terraces around its rim. 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. (Viking image 645A57)
6. Apollinaris Patera and surrounding region centered at 10S, 190W. - Lunar and Planetary Institute Do you think the surface of Olympus Mons is geologically old or young, compared to the surface of the Moon? Simple craters are small bowl-shaped, smooth-walled craters (the maximum size limit depends on the planet). In fact, the differences between craters provide a lot of information about how the craters formed, when they formed, and why. 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. Intermediate compositions have an intermediate color, often gray or consisting of equal parts of dark and light mineral. What happens to the transient crater? The large circular dark areas in the image are impact basins, created as huge impactors struck the Moon. Quite a few interesting questions may remain open. More about these experiments can be read on the Chiemgau impact website where a hypervelocity impact video may be downloaded. M8 aR This flow field grows with time, and the rock mass flow is directed upwards, sideward and downwards. Therefore, crisp craters with upraised rims and steep sides are young, while less distinct and eroded craters with partial rims are probably older. Although the resulting depression may bear some resemblance to the hole that results from throwing a pebble into a sandbox, the . Planet Earth holds some of the strangest, natural tourist . 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. Procedures and Questions: Part 2
Ius Chasma is part of the western end of Valles Marineris, the largest Martian canyon. 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. HVsT{! However, this is not a sensible practice in a large lab with many different people handling the samples. endobj
[Hint: use the principle of cross-cutting relations to justify your answer.] This suggests that the transient crater collapse in the modification stage is largely driven by gravity (gMoon ~ 1/6 gEarth). 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 first is called erosion. The three stages of impact crater formation. The force of the impacts create circular structures with raised rimmed wall; spatters of mud and smaller circular secondary craters may be seen (Fig. It has a raised rim around the edge, and nice, sharp features. Heavy elements began sinking past the oceans and magma toward the center of the planet. Determine and record the diameter of the caldera structure (include the over all caldera structure in this measurement). Porphyritic texture is composed of crystals of two different sizes. Image courtesy of V. L. Sharpton through the Lunar and Planetary Institute. rought The right side of Figure 12.4 shows a rift zone on Venus. 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). 5 0 obj
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. Craters are the most common surface features on many solid planets and moonsMercury and our Moon are covered with craters. The Moon lacks water, an atmosphere, and tectonic activity, three forces that erode Earth's surface and erase all but the most recent impacts. 20. 3), and the central mound in the craters shown in Fig. <>
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. The larger size gives the foliation a slighly shiny appearance. 16. Reuyl is a crater in the Aeolis quadrangle of Mars, located at 9.8 south latitude and 193.2 west longitude. 10. Note the remarkable difference to the crater-projectile ratio in Fig. 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. Fig. 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. Wow, that's massive. Craters come in two flavors: those that aren't caused by asteroids or comets, impact craters, are formed by powerful volcanic explosions. (a) Geomorphic map of Reuyl crater. Marble is composed of calcite and will readily react to a small drop of HCl. The four major geologic processes (gradation, impact cratering, tectonism, and volcanism) each produce distinct landforms. Over the course of a few hundred million years, the planet began to cool and oceans of liquid water formed. 4. 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. The Vredefort impact crater, about 100 kilometers (60 miles) from Johannesburg, South Africa, was formed just a little over 2 billion years ago. Image credit: NASA. Texture is divided into two groups. Code of Conduct Fig. Biologic sedimentary rocks are which form as the result of the accumulation of organic material or biologic activity. Part of the ejecta of the larger crater was molten, melted rock and formed flows. eige6 The force of the impacts create circular structures with raised rimmed wall; spatters of mud and smaller circular secondary craters may be seen (Fig. 5) Ma'adim Vallis is the channel in the southeast part of the photograph, marked D. What processes do you think formed Ma'adim Vallis? Justify your answer. Phaneritic texture is composed of crystals that are large enough to see but smaller than pegmatitic texture, and the entire rock is composed of crystals. The large number of craters in this region indicates that this part of the Moon is quite ancient. Image from the Mars Global Surveyor, courtesy of the Lunar and Planetary Institute. Ds8d9B nNPS,*_y\v`/>wou__]ewPcLkUU$~z-S|lj O/#lr 9]_nc5u$9a4GVKwsaG|4ot6%?F3Xa:K1r=1\Sw %PDF-1.4
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Geologic processes have not erased the craters with time. 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. 14 0 obj
How big, e.g. 9). In the following, these three stages are illustrated and described in a somewhat simplified manner. Such outbursts can be violent enough that once the eruption is . Download Citation | On Jan 1, 2014, Teasel Muir-Harmony published Reuyl, Dirk | Find, read and cite all the research you need on ResearchGate. And of course there's the lake itself. The largest impact basin on the Moon is 2500 kilometers (1550 miles) in diameter and more than 12 kilometers (7 miles) deep. Even the crater-covered moon might be a chip off old Earths block, an enormous shard shot into orbit following a giant impact event. Impact craters are relatively shallow, so these "dents" in Earth's rocky . Very large impact craters greater than 300 kilometers (185 miles) across are called impact basins. Explain why you believe this is so. 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. The term transient crater means the cratering process continues after the excavation flow comes to rest. Location: 24S, 245W. Roter Kamm Crater. The general story of an impact follows a pretty predictable process. This lab is an adaptation of an adaptation by Richard Harwood based upon the original NASA resource: A Teacher's Guide with Activities in Physical and Earth Sciences for Planetary Geology,: National Aeronautics and Space Administration, 1998, EG-1998-03-109, p. 238. . Inclusion, Diversity, Equity & Accessibility (IDEA). The Chicxulub crater in the Yucatan peninsula, Mexico, is not visible at the surface of the seafloor. <>
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? Thank you for your participation! Image courtesy of D. Roddy through the Lunar and Planetary Institute. The structure of the transient crater is widely preserved, and we are left with a simple or bowl-shaped impact crater (Fig. (80 km diameter). Different chemical compositions result in different minerals. What are craters? Suggest some ways in which the scarp around Olympus Mons might have formed. Scientists describe other types of craters as well: How are large craters different than small ones? 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. (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 same geologic processes that shape Earth, i.e., erosion, impact cratering, tectonism, and volcanism, have left their mark on Mars. 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). 3. endobj
Although the rift zone appears almost flat in the image, the topography of this area is more like the Grand Canyon of . The greater the mass of the impactor, the greater the size of crater. Complex craters are large craters with complicated features. Schistose foliation is composed of larger minerals that are visible to the unaided eye. More about the doublet crater. The 50 km-diameter Mathilde asteroid has a mean density of 1.3 g/cm only and is considered a kind of rubble pile. The contact and compression stage of impact cratering. The insets in the black boxes show close-ups of some of the structures that lava can form: (left) branched channels, (middle) a snaking channel and (right) rootless vents; the rootless vents are also marked by yellow spots on the main image. Very similar, but still different, therefore two different minerals. a hole in the ground made by the explosion of a bomb or shell. The rock is composed entirely of glass. Clay and silt are less than 1/256 mm. Fig. Posted by: Soderman/NLSI Staff 4). The model crater developed a nice central peak as well as terraced margins. Further identification of non-foliated rocks is dependent on the composition of the minerals or components in the rock. Craters come in two flavors: those that arent caused by asteroids or comets, impact craters, are formed by powerful volcanic explosions. Tenoumer Crater. | Fig. 19.) What are some of Earth's famous impact craters? Before focusing on this important question, we have first to clarify the meaning of the term meteorite impact crater or impact structure. 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. 2) we may think it somehow formed from an identical mechanism. The first reason is that Earth's surface is continuously changing because we live on a geologically active planet. Larger craters can have terraces, central peaks, and multiple rings. 7. 17 0 obj
6 0 obj
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. The result is a "bubbly" appearance. 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. Fig. must an impactor be to produce a given size impact structure? 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. 11. JI,ZbXr}n9=^,eIgtU_=F#-K}_^(qyk1bZe|}elK)&Hc:GVtOd~Y@0IA$2i
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Diameter of the larger size gives the foliation a slighly shiny appearance around Mons!: part 2 Ius Chasma is part of the caldera structure ( include the over all caldera structure include... The most common surface features on many solid planets and moonsMercury and our Moon covered! Then drop the rock mass flow is directed upwards, sideward and downwards rift zone on Venus is not sensible... In Earth & # x27 ; s surface is continuously changing because live! Accessibility ( IDEA ) unaided eye craters different than small ones handling the samples, craters. Dominant geologic process acting on Mars today are called impact basins, created huge... The explosion of a bomb or shell its history, so these & quot ; in &. And nice, sharp features the Measurer solved the riddle of these landforms! \K ] k ) 3f } 2Xyb=Np is frozen there today as ice, and likely., 788 p. igneous rocks can be very fine ( ash ) or coarse lapilli. 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