Geology Lab 1

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George Mason University *

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Geology

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Apr 3, 2024

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Exploring Mars Geology Lab Procedure and Report Group Member Names: Roll: _____Latrell Pryor Anthony Gemma Hannah Dawson Kerry Bishop______________________ Leader (manages people and time, all should participate) ___________________________ Recorder (keeps track of results and records lab report) ___________________________ Checker (makes sure all results are correctly reported) Your Lab Group Number ___________________________ Date __________________ Purpose: Learn how to estimate the age of the surface of a terrestrial-type planet or moon by using satellite images to quantify the crater densities (number of craters per unit area). Get familiar with characteristic features on Martian surface using the Marstrek website, which is based on a Geographic Information Systems program that can be used in a number of ways to explore the Martian surface. Introduction: Craters on Mars are produced by the impact of asteroids and comets that have penetrated the Martian atmosphere. One rule of thumb is that an impactor (i.e., anything impacting the surface causing a crater to form) will carve out a crater about 20 times its own diameter. After a crater has been formed, there are several factors, such as erosion by water and wind, which can gradually obliterate the crater. On Mars, it is estimated that wind-carried dust can completely erode a small (1 m) crater in about a million years, and a large (1 km) crater in about 100 million years. Craters are also degraded by lava flows, which can totally alter surface features in a very short period of time. A careful study of the number and size of craters gives us a way to estimate the age of the rocks that make up the surface of a planet. Part I: Craters and Surface Features on Mars Use the following website as a resource: https://en.wikipedia.org/wiki/Planetary_nomenclature Explain what the following terms mean, a. Mons : Mons itself refers to a mountain. Specifically, a mountain on a celestial body.

b. Terra : Terra refers to an extensive land mass. Many people refer to the Earth as terra, as well as land in general. c. Planitia : Planitia refers to a low plain. d. Planum : Planum refers to a high plain, otherwise known as a plateau. e. Valles : Valles refers to a valley. f. Montes : Montes refers to a mountain range. Specifically a mountain on a celestial body. g. Chasma : Chasms refers to something that is deep or elongated. Chasma is specifically a narrow and long, steep-sided depression on a planet. Part II: Using Craters to Determine Surface Age: Region 1 The number of craters per unit area on the surface of a planet or moon can be an indicator of the age of the surface. Earth is constantly being resurfaced by earthquakes, volcanoes, and also by the effects of wind and water erosion. Hence impact craters on Earth, even most of the large ones, are rather quickly erased or obscured. On the other hand, the Moon has experienced little geological activity over most of its history, and therefore craters on the Moon survive for millions of years. Therefore the Moon remains heavily cratered, unlike the Earth, even though both have been exposed to a similar rate of impacts by objects from space. Mars is somewhere between the Earth and the Moon, because there is evidence for water erosion in the distant past, but not currently. Consequently, the regions on Mars that haven’t experienced much surface activity are more heavily cratered than other regions. Your mission today is to examine three regions on Mars, measure the number of craters per unit area in each one, and then use the data to obtain a relative age for each region. We can determine the age of a planetary surface by counting the craters on the surface. To begin counting craters on Mars, visit the Mars Trek website, https://trek.nasa.gov/mars/ First, click on the Tutorial button to learn how the system works. Next, click on the notice the “ Basemaps ” icon in the lower right-hand corner of the screen: Menu icon Basemaps icon

Then, turn on the “ Nomenclature ” function (this adds region labels to the Mars map), and also turn on the “ Graticule ” function (this adds gridlines to the Mars map). a) In the Marstrek website, select a region in the southern hemisphere of Mars somewhere between latitudes -20 and -40 . Click on the “ + ” icon to zoom in until you see a 5x5 region that looks something like this: Next, click on the “ Menu ” icon, select “ Calculate Distance ”, and then click on “ Line ”, as indicated below: Then, return to the Mars map and measure the length of one side of the 5x5 region you selected. Record the measured length in one of the green shaded cells provided Excel spreadsheet. Next, use the same procedure to measure the length of another side of the 5x5 region, perpendicular to the first side, and record the length in the other green shaded cell the

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Excel spreadsheet. The area of the region will be auto-computed in cell D4 of the Excel spreadsheet. Record the requested information in the areas indicated below. Insert screen capture for Region 1 below: Indicate the coordinates and area for the First Target Region below: Region 1 is between Longitudes: __-115_______ and ____-110_____ Region 1 is between Latitudes: __-35_______ and ___-40______ Region 1 Area in km 2 (from Excel spreadsheet): ___72171_______________ b) Zoom in so that you can clearly see all of the craters in the 5x5 grid square you are measuring. Next, click on the “ Menu ” icon again, select “ Calculate Distance ”, and click on “ Line ”, and measure the diameter of each crater in the selected 5x5 region. Measure all of the craters larger than 8 km in diameter in the target grid section that you have selected . Record all of the measurements in the orange highlighted column of the Excel spreadsheet. Each crater size should be entered into a separate orange cell in Column A.

Next, count how many craters are in each size range indicated in Column B of the spreadsheet, and record those totals in Column C. This will auto-generate a plot of the crater density as a function of crater size. c) Compare the plotted crater density distribution with the curves plotted on the ISOCHRONES tab of the spreadsheet. The curves on the graph are called “isochrones” (meaning “same age”), and describe the age of the surface on which the craters formed. These graphs not only show that there are more small craters than large ones, no matter the age of the surface, but they also show that the greater the number of craters per square kilometer of surface, the older the surface is. Note that the proportion of small craters to larger ones is about the same throughout the solar system, regardless of the age of the surface. Indicate the estimated age for the First Target Region below: Region 1 estimated age: _1,000,000,000 years old____ Part III: Using Craters to Determine Surface Age: Region 2 Repeat the above procedure for another 5x5 target region chosen from the volcanic region of Mars around the Tharsis Bulge . Analyze as before, and record the results and plots in your spreadsheet. Insert screen capture for Region 2 below:

Indicate the coordinates, area, and estimated age for the Second Target Region below: Region 2 is between Longitudes: ______5W___ and _____0____ Region 2 is between Latitudes: ______30s___ and ______25s___ Region 2 Area in km 2 (from Excel spreadsheet): ______78261.7375____________ Region 2 estimated age: ___Little over 1 billion years__ Part IV: Using Craters to Determine Surface Age: Region 3 Repeat the above procedure for another 5x5 target region in the northern hemisphere of Mars between latitudes 20 N and 40 N . Analyze as before and records the results and plots in your spreadsheet. Insert screen capture for Region 3 below:

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Indicate the coordinates, area, and estimated age for the Third Target Region below: Region 3 is between Longitudes: __20N_______ and ___40N______ Region 3 is between Latitudes: ___-60______ and __-40_______ Region 3 Area in km 2 (from Excel spreadsheet): ___1,074,384km^2_______________ Region 2 estimated age: __1,000,000,000___ Part V: Conclusion Based on the observed number of craters you counted in each of the three regions, rank the three regions you have studied by age, and write a short report on the results you obtained. Did you find significant differences in the ages of the three regions? Explain what you think is going on to explain the age differences you found. When observing our graphs it showed that there was fewer cratering in the northern region of Mars. All of our regions had similar amounts of cratering which led to the estimated surface age of all three being about 1,000,000,000 years. Submit the Lab Report, including the coordinates and areas for the three target regions on Mars, into the Dropbox. Also submit the associated Excel spreadsheet including all of the data and plots that you obtained.

Geology Lab 1

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