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Name _________________________________ Date ________________ Section _________________________________ Score ________________ Partner _________________________________ I.I’s ________________

Lab 13 – The Mars Lab Tutorial

Materials Needed: The Mars Lab utilizes four Shaded Relief Maps (MC-7, MC-15, MC-19, and MC-25) prepared from the Mariner 9 Mission to Mars by the USGS. You will begin with MC-25. The Mars Worksheet will utilize additional USGS maps of Mars. You will obtain these maps from https://astrogeology.usgs.gov/search?pmi-target=mars. Use the filters as shown below and do not use the revised version, but the original version:

INTRODUCTION – The Mars-like Planet

The large number of craters on Mars reminds us of the Moon and Mercury. But the sand dunes, volcanoes, and dry river valleys remind us of processes found here on earth. Indeed Mars is in many ways a halfway planet; it has a surface much less active than the direst desert on earth, yet it seems like a tropical wet-house when compared to the bare and dry surfaces of Mercury and the moon. But in addition, Mars is also a world of its own. The great volcanoes, chasms, and dune fields of Mars are unlike anything found on earth or the other planets. In the final analysis, Mars is more like Mars than anyplace else.

In this lab, you will sample some of the diversity of Mars by examining some maps of various regions on Mars. These maps include several regions selected from the Atlas of Mars by Batson, Bridges & Inge. Of course, a complete survey is out of the question in such a short time, but as you work through the worksheets provided, we hope you will appreciate some of the surprising variety of landforms found on this bone dry desert world. Some of the key concepts that you will explore are given below. As you

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read the introductory pages, please answer the questions and fill in the blanks by using the provided maps.

I. IMPACT CRATERS AND STRUCTURES

During the past 4.5 billion years, countless tiny, small, medium, large and enormous meteoroids have struck the surface of Mars. As on the other terrestrial planets, there are small impact craters, medium-sized impact craters with central peaks, multi-ring structures and large basins – all due to the influx of impacting meteoroids and asteroids. However, these craters have been subject to much more wind and water erosion than craters on the moon or Mercury. In the Thaumasia Quadrangle (MC-25) are examples of several varieties of impact craters. Most of the moderately large craters are named whereas the smaller craters are designated by letters. 1. Please record the names and diameters of the following medium-sized craters found

at the designated positions: Name Latitude Longitude Size (km) _______________ -51 S 113 W _______________ _______________ -47 84 W _______________ _______________ -52 70W _______________

Use the scale at the bottom of the map to determine the diameters. Notice that the interior of these craters are relatively smooth. Winds have smoothed the interiors of many Martian craters. 2. What is the name and diameter of the large crater at longitude 82°W and latitude

-53°S? ______________________ (82°W -53°S) ___________________ km What is unusual about this crater? ____________________________________________ Smaller Craters and Central Peaks The first letter (capitalized) for the smaller craters is assigned in terms of increasing longitude (to the west and right) and the second letter is assigned in terms of increasing latitude (to the north and up). Several of the smaller craters have small central peaks – mountains that were thrown up in the center of the impact crater when the craters were formed. Give the latitude, longitude, and diameter of these four craters:

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Name Latitude Longitude Size (km) Xp __________ S __________ W ___________ Wpd __________ S __________ W ___________ Vx __________ S __________ W ___________ Aka __________ S __________ W ___________ You may have noticed that these small craters are not really small. While all such craters do not have central peaks, many of them do. The peaks can be further studied to give us more information about the energy of the impacting asteroids and the strength of the Martian rock layers. Between Latitudes 40 to 48 South and Longitudes 100 to 110 West, is a large smooth roughly circular basin. This may be the mark of a very large and ancient impact structure that has since been filled with lava and/or dust and eroded by water and/or winds. Whether this is true in this particular case would require additional study. What is the name of this large planum? _____________________________________ Planum Relative Age One of the craters labeled “Pg”, (latitude 56.5°S, longitude 93°W) has a small interior crater, Pgc. It is obvious that Pgc is younger than Pg. the same principle can be used for overlapping carters. In these cases a younger crater has partially obliterated an older crater’s rim. Use this principle to determine which crater is older; Wq or Xq (~ 43°S, 112°W). ____________

II. VOLCANIC ACTIVITY Volcanoes Several volcanoes on Mars are much larger than any found on earth. Their summit calderas may be many kilometers high and their flanks sometimes extend for hundreds of kilometers. A few scattered meteorite craters on their flanks suggest that many of them have formed during the past few hundred million years. Here again, we see evidence that Mars is much less active than the earth, but much more active than the moon and Mercury. Three very large, very ancient and very different types of volcanoes are found in the Elysium Quadrangle of Mars (MC-15). Elysium Mons (Mons = Mountain) is a shield volcano roughly circular with relatively smooth flanks that exude from a central vent or central caldera. Notice that the base of the volcano reaches from 209-217°W. A slightly smaller mountain, which has a larger caldera, is Albor Tholus, centered at approximately 19°N, 210°W. A tholus is an isolated dome shaped hill or mountain. What are the diameters of these two huge mountains and their central calderas? Base Diameter Caldera Diameter Elysium Mons ________________ km ________________ km Albor Tholus ________________ km ________________ km

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Caldera After a period of volcanic activity the magmatic pressure which caused the volcano begins to subside. Sometimes the pressure drops so much that the center of the volcano collapses. This central crater is called a caldera. The caldera is different from an impact crater is several ways, some of which you will discover by observation during this lab. Two important differences are the lack of central peaks (sometimes found in impact craters, but never found in calderas) and the lack of an uplifted rim around a caldera. The rim of an impact crater is made of overturned rock. Look carefully at the differences between the flanks and the calderas of the two large volcanoes and the rims and interiors of the impact craters Eddie (12°N, 218°W), Lockyer (28°N, 199°W), and Wg (8°N, 219°W). The impact craters generally have raised rims and sometimes have central peaks. The volcanoes never have central peaks. At 3°N, 196°W is a nearly buried feature labeled “Jc”. Is Jc a relic impact crater or volcano?____ Patera A complex or irregular volcanic crater is called a patera. A large, ancient volcanic structure is found in the Elysium quadrangle (15°N, 181°W).

III. RUNNING WATER Most of the surface of the Margaritifer Sinus quadrangle (MC-19) is very ancient. Ancient craters that are believed to be perhaps three billion years old clutter the surface of the region. In addition, however, there is also evidence of ancient beds of running water in the Margaritifer Sinus quadrangle. For example, what is the name of the valley that flows to the northwest from the edge of the map up into the Holden crater (26°S, 34°W)? _________________________________________ Notice that the vallis is quite different from the nearby Erythrea Fossae. The fossae are believed to be rifts (pulled apart by rock movements – tectonics instead of erosional features). What is the valley south of Jones crater (20°S, 20°W)? __________________ Note that the valleys look like tree branches (so called dendritic forms) where smaller tributaries have run into larger streams. Additional forms are also in evidence. What is the name of the chasm in the northwest corner of the map? __________________ Chasm What are the names of the two chaotic tumbled regions in the northernmost regions of the map? ___________________ Chaos and ______________________ Chaos. Chaotic regions may be due to underground water and/or moving ice.

IV. EROSION, WATER, WIND, AND ICE Polar Regions Both poles of Mars are covered with frost, snow, and ice due to both carbon dioxide and water. The poles wax and wane with the seasons being larger during their respective winters and smaller during their respective summers. They also exhibit evidence that Mars may have had its own ice ages and warm ages over the past thousands and millions

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of years. Some of the sand dune fields near the poles are larger than any others known in the solar system. A Very Martian Landscape The Cebrenia Quadrangle (MC-7) of Mars offers a very Martian landscape. Can you recognize these features? Name Diameter 1 A moderately large impact crater in the

middle of the map? [48°N, 220°W]

__________________ _________ km

2 A very large volcano at the bottom of the map?

__________________ _________ km

3 An ancient valley slightly to the SW [40°N, 225°W; 35°N, 220°W]

__________________ Vallis

4 An ancient, fairly straight fault near the above Vallis? __________________ Fossae

What is unusual about the craters Tyndall (Dg), El (46°N, 191°W) and the unnamed crater centered near 32°N, 188°W? ___________________________________________________________________________________________________________________

Pedestal Craters In the northwest portion of the map are some curious craters that seem perched upon domical hills. These strange features were apparently formed from impacts that melted enormous amounts of ice frozen in the ground. Name (Label) Lat Long Name (Label) Lat Long __________________ 56°N 220°W __________________ 63°N 228°W Aeolian or Wind Erosion Sand dunes, bright and dark windblown streaks, hundreds of kilometers in length, and wind filled valleys and craters offer plentiful evidence that Martian wind affects the surface of Mars. Do you see any features on MC-17 or MC-15 that are due specifically to the action of the wind? _____________________________________________________________________________________________________________________________________________________________________________________________________

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When you have completed your tutorial, check the key to verify your answers. Your answers should be accurate to approximately 15% or better. If most of your answers are correct and if you understand any errors that you might have made, you are ready to proceed to the graded worksheet.

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BIBLIOGRAPHY [Introductory, Semi-technical & Technical]

Baker, Victor R. (1982). The Channels of Mars. University of Texas Press. Batson, R.M., Bridges, P.M. & Inge, J.L. (1979). Atlas of Mars (NASA). Beatty, J.K. (Sept 1976). “Viking Lands on a Very Red Planet”, Sky and Telescope v. 52. Beatty, J. Kelly (Dec 1976). “Vikings Rest During Mars’ Conjunction”, Sky and

Telescope vol. 52, #6, pp. 404-409. Beatty, J.K., O’Leary, B., & Chaikin, A. Eds. (1990). The New Solar System (3ed). Sky

Publishing Corp. Carr, Michael (1981). Surface of Mars. Yale University Press. Carr, Michael (1996). Water on Mars. Oxford University Press: New York. 239 pages. Kiefer, H.H., Jakosky, B.M., Snyder, C.W., & Matthews, M.S., Editors (1992). Mars.

University Press of Arizona Press: Tuscon. Masursky, Harold (Aug 1972). “The New Mariner 9 Map of Mars”, Sky and Telescope

vol. 44, #2, pp. 77-82. Weaver, Richard F. (Feb 1973). “Journey to Mars”, National Geographic Magazine vol.

143, #2, pp. 231-263.

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Name _________________________________ Date ________________ Section _________________________________ Score ________________ Partner _________________________________ I.I’s ________________

Lab 13 – The Mars Lab Worksheet

Materials Needed: You will need the Topographic Maps of Tharsis Quadrangle (MC-9), the Oxia Palus Quadrangle (MC-11) and the Coprates Quadrangle (MC-18) as well as the Controlled Photomosaic and Topographic Maps of the Tharsis Northwest Quadrangle (MC-9NW). Note that you will be using three separate maps of the Olympus Mons region. Grading Notes: Several times you will be asked an open-ended question requiring more than a simple name, number, or a yes or no. Do not leave these questions blank. These questions are graded generously – unless you fail to answer them. Questions that require written answers will count twice as much as other questions.

I. MORE ON CRATERS

The regions we shall examine in the Worksheet portion of the Mars Lab are not as heavily cratered as some of the regions examined in the Tutorial. This is because the regions we shall examine in the Tutorial have been greatly altered by wind, rain, ice, and volcanism. Even within these quadrangles, however, there has been a great deal of variety in erosional processes. These variations in crater density tell us a great deal about the age of the features being examined. Regions that have a low crater density are younger than the regions that have been extensively cratered. Furthermore, regions that have many small craters are more likely to have a few large craters.

Variations in Crater Density (MC-9, MC-11, MC-18) Several regions have been selected from these quadrangles that represent some of the range in crater density found on Mars. Examine the following regions and determine the approximate number of craters in each 5° x 5° region: (Count unlabeled and labeled craters – be attentive, a careful examination reveals a surprisingly large number) Between 25° & 30°N and 115° & 120°W (MC-9) ____________ less than 10 _________________ 11-30 ___________ more than 30 Between 5° & 10°S and 70° & 75°W (MC-18) ____________ less than 10 _________________ 11-30 ___________ more than 30 Between 5° & 10°N and 40° & 45°W (MC-11) ____________ less than 10 _________________ 11-30 ___________ more than 30

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Give the name and size of the two largest impact craters on MC-11: Name __________________________________ Diameter _________________ km Name __________________________________ Diameter _________________ km Give the name and size of the two largest impact craters on MC-18: Name __________________________________ Diameter _________________ km Name __________________________________ Diameter _________________ km Give the name and size of the largest impact crater* on MC-9: Name __________________________________ Diameter _________________ km *It is not Uranius Patera – Uranius Patera is volcanic. Which Quadrangle is the most heavily cratered? How so? Does the Quadrangle with the most craters have the largest craters? Explain your answer. Many astronomers and geophysicists believe that perhaps three or four billion years ago, there were probably ancient rivers on Mars. After Mars began to dry up and cool off, there were apparently occasional floods due to widespread melting – perhaps during volcanic eruptions and/or due to impacts from relatively large asteroids and comets. The large and now dormant volcanoes on Mars, particularly those in the Tharsis region, have apparently erupted during the past billion years and thus the volcanic features are much younger than the features due to water erosion. Wind erosion, however, continues into the present. Are the features on your charts consistent with these ideas? Can you give specific examples? Some ideas to keep in mind: (1) whenever there are few craters, the surface is relatively young, (2) large impacts are rare, (3) the terrain around the ancient riverbeds is much more heavily cratered than the terrain around the large volcanoes, and (4) while not evident here, windstorms on Mars are so widespread that they can sometimes be observed from earth.

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II. VOLCANOES For this portion of the lab, you will need to examine the topographic map of the Tharsis Quadrangle (MC-9). Later, you will examine one of these giant volcanoes (Olympus Mons) in more detail by using some more detailed maps of the Northwest quadrant (MC- 9NW) Volcanoes: Sizes and Elevations – Volcanoes of the Tharsis Bulge What are the diameters of: Ascraeus Mons ___________ km Bibles Patera ___________ km Ceraunius Tholus ___________ km Olympus Mons ___________ km Pavonis Mons ___________ km Uranius Mons ___________ km Uranius Patera ___________ km

[The entire mountains, not just the calderas.] The largest volcanoes on the earth are approximates the size of Biblis Patera and Uranius Tholus – the smallest of these seven structures. These volcanoes are also very high. Check the red topographic contours to determine their elevations. What is the highest elevation found on Olympus Mons? ____________ km What is the highest elevation found on Pavonis Mons? ____________ km What is the highest elevation on Ascraeus Mons? ____________ km What is the name of the volcano with the largest Caldera? (It is not Olympus Mons) How large is this caldera? Name ___________________________________ diameter ________________ km A caldera is a larger crater caused by sinking of the central region of a volcano after the pressure of the outflowing magma begins to decrease. The calderas at the summits of Martian volcanoes are very similar to those of some terrestrial volcanoes except that the Martian volcanoes and calderas are sometimes much larger. However, the Martian volcanoes frequently exhibit additional cratering found on their flanks that are due to meteoroidal impact. These impact craters often give us a way of crudely estimating the volcanoes’ ages. Most of the Martian volcanoes seem to be between one hundred million years and one billion years old. Age and Erosion of Volcanoes Give the labels of the three largest impact craters on the flanks of Olympus Mons and the largest impact craters on the flanks of Ulysses and Ascraeus Patera. (longitude and latitude are provided) Olympus Mons ______________ at 133°W 17.5°N Olympus Mons ______________ at 132°W 18°N Olympus Mons ______________ at 132°W 22°N Ulysses Patera ______________ at 121.5°W 4°N

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Ascraeus Patera ______________ at 101.5°W 12.5°N What evidence is there that crater MC-9 Sc is younger than Ulysses Patera? What evidence is there that the impact crater on the northern edge of Ceraunius Tholus struck before Ceraunius Tholus became extinct? Close-up of Olympus Mons – you will need both the Controlled Photomosaic and the Topographic Map of the Northwest (NW) section of the Tharsis Quadrangle for this section (MC-9NW). The sunken central caldera of Olympus Mons is found at approximately 133°W, 18°N in the SW portion of the Controlled Photomosaic. Notice how the flows seem to have flown out in all directions from these central vents. What is the longest diameter you measure for the caldera? ___________________ km Several small craters on the flank of the Olympus Mons are not visible in the larger quadrangle map. Give the size and coordinates of three of them. A magnifying glass may help. Size Coordinates Size Coordinates Size Coordinates

___ km _____________ ___ km _____________ ___ km _____________

To the north of Olympus Mons is an enormous lava field that actually extends beyond the SW portion of the quadrangle. Note again that there are few impact features, making this a very young surface for Mars. Still, if you look carefully you will generally find some more small impact craters on the flanks of most volcanoes. This tells us that even though the volcanic regions are much younger than much of the Martian surface, nevertheless, they have ages in the millions of years. It is not every day that a 5-20 kilometer impact crater is formed. What is the altitude at the top edge of the steep edge of the eastern flank (around 129.2°W, 17.5°N) of Olympus Mons? ___________ km or ____________ m

[1 km = 1000 meters – your answers should be greater than 20km or 20,000m] What is the altitude at the bottom edge of the steep edge of the eastern flank (around 129.2°W, 17.5°N) of Olympus Mons? ___________ km or ____________ m So, how far from the top to bottom for these cliffs on the east flank of Olympus Mons? ___________ km or ____________ m

[While the cliffs are not nearly as high as the summit of Olympus Mons, they are higher than many high mountains on earth.]

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III. CHASMS AND VALLEYS Valles Marineris The Coprates Quadrangle (MC-18) has one of the longest known valleys in the solar system. The valley has been formed from a large rift near the equator of Mars which has been further eroded by wind and water. The valley actually extends beyond the picture here. How wide is it at its widest point (Melas Chasma)? (Ignore the extra tributary) ____ km Using the topographic contours, how much depth is there between the highest rims near Ius Chasma (to the west) and the lowest points in the valley near Eos Chasma (to the east)? Highest rim elevation _________________ km Lowest valley elevation _________________ km difference _________________ km It you look very carefully, a few craters can be found in the valley itself. There are many more impact craters to the north and south of the valley than in the valley itself. This tells us that the floor of the valley and quite possibly the valley itself is much younger than the surrounding plains. On the photographs, there is not much evidence of running water. However, there is evidence of several enormous landslides. For example, how high are the cliffs at Melas Chasm (in the central regions of the valley)? top = ________ km bottom = _______ km total drop = _________ km

IV. RUNNING WATER In the Oxia Palus Quadrangle (MC-11) we find a different form of valley. The crater at 3°N and 16°W seems to be the starting point for a flood that tore toward the Chryse Planitia. What is the label of the crater? ______________________________________________ What is the name of the valley? _____________________________________________ How does the topography support this hypothesis? (Hint – note the elevation of the Chryse Planitia, negative numbers are below mean elevation)

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Are the valleys in the Southwest of the map such as Shalbatana Vallis and Simud Vallis consistent with the idea that liquid material (presumably water) once flowed into Chryse Planita? Explain. What are the names of the odd landforms found at the head of Tiud Vallis and Simud Vallis? These odd landforms may be due partially to the collapse of regions that experienced catastrophic melting of enormous quantities of frozen ice. Whatever their source, these features remind us that there is a great deal about Mars that we do not understand. After completing the worksheets, submit them to your instructor.