Geology 101 Lab Worksheet: Topographic Maps

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1 Geology 101 Lab Worksheet: Topographic Maps Name: Refer to the Topographic Maps Lab for the information you need to complete this worksheet ( In this lab, you will examine the earth through topographic maps. Topographic maps allow you to view and study the shape of the earth s surface, in enough detail to analyze processes that have formed the landscape and may continue to change the landscape in the future. Materials Needed This worksheet A computer with access to the Internet A ruler A pencil Red and blue colored pencils Topographic quadrangle (provided) There are three parts to this lab: Part 1: Develop your topographic map reading skills by working with simplified diagrams that illustrate key elements of topographic maps. Part 2: Practice your map reading skills by interpreting snippets from topographic maps. Part 3: Apply your skills to interpret an actual topographic map of a full quadrangle. Due by the time the next lab begins next week: 1. This work sheet, completed. Lab Worksheet Topographic Maps page 1

PART 1: READING CONTOUR LINES AND ELEVATIONS, DISTINGUISHING SLOPES, AND APPLYING THE RULE OF VS In this portion of the lab you will work with simplified diagrams that will build your skills at

2 PART 1: READING CONTOUR LINES AND ELEVATIONS, DISTINGUISHING SLOPES, AND APPLYING THE RULE OF VS In this portion of the lab you will work with simplified diagrams that will build your skills at reading key elements of topographic maps. Refer to the Topographic Map Lab webpage for full-sized versions of the diagrams ( Answer the questions below each of the diagrams. Topographic map diagram 1 1. Of the two partial topographic maps above, which one depicts the steeper landscape? (Circle the correct answer.) map on the left map on the right 2. How can you tell? 3. Use the contour interval and the map scale to measure the steepness between the marked points on each map. The steepness is the elevation change divided by the horizontal distance. In other words: steepness between points = elevation change horizontal distance On United States Geological Survey topographic maps, the steepness, which is also called the gradient, will be in units of feet/mile. Fill in the blanks below as you calculate the two steepnesses: Map 1 steepness: = The second blank is to write the steepness units in, to make your answer complete. Map 2 steepness: = 4. Do your calculated results confirm your answer to the first question above? Lab Worksheet Topographic Maps page 2

3 Topographic map diagram 2 The topographic map above shows a hill with a peak elevation of 2574 feet above sea level. Four valleys and four ridges radiate from the peak. 1. Using a blue colored pencil, draw a line along the middle of each valley, showing where streams would run if there were a stream in each of the valleys. Begin each blue valley line at the highest contour line on the mountain and continue each blue line to the edge of the map. 2. Using a red colored pencil, trace the crest of each ridge. Begin each red ridgeline at the highest contour line on the mountain and continue along the crest of each ridge to the edge of the map. 3. The rule of Vs refers to how streams cross contour lines: Where a contour line crosses a stream, it makes a V pointing in the uphill direction. Assume the blue lines you drew are streams. The contour lines make Vs where they cross the streams. Do the Vs point uphill or downhill? Lab Worksheet Topographic Maps page 3

4 Topographic map diagram 3 Lab Worksheet Topographic Maps page 4

5 The topographic map on page 4 (above) shows two streams. 1. Based on the rule of Vs, which general direction is upstream? (Circle the correct answer.) North South East West 2. Which is the general direction that the streams are flowing? (Circle the correct answer.) North South East West 3. One contour line has its elevation labeled on the map. Complete the map by filling in all the other gaps in the contour lines with the correct contour line elevations. 4. What is the elevation at point a on the map? 5. What is the elevation at point b on the map? Topographic map diagram 4 Draw the topographic profile from A to B of the map above. Draw the profile within the grid below the map. Lab Worksheet Topographic Maps page 5

6 PART 2: MAP SNIPPETS This portion the lab, including the images copied from US Geological Survey maps, was originally created by Tom Braziunas. It is modified and used with permission. Refer to the Topographic Map Lab webpage ( ) for the full-size colored maps and answer the questions below each map. If not indicated, assume north is to the top. CARKEEK PARK The small portion of a topographic map above shows a road and creek (blue-green line) in Carkeek Park. 1. Based on the "Rule of V's," which way the creek is flowing? 2. What do the little black boxes symbolize? 3. What source did you use to find what the little black boxes symbolize? CARKEEK PARK (continued) 4. What is the elevation change from one index contour to the next? (Remember the index contours are the bold contour lines with labeled elevations. The contour lines between index contours do not have their elevations labeled.) 5. How many contour intervals (spaces between contour lines) are there between the index contours? 6. Find the elevation change for each contour interval by dividing the elevation change between index contours (answer to question 4) by the number of contour intervals between them (answer to question 5). (fill in the blanks, including units in the last blank). ft intervals = ft./interval Your answer is the contour interval of this map. 7. What is the elevation difference between the two red arrows? Lab Worksheet Topographic Maps page 6

7 GREEN LAKE 1. What is the contour interval on the map of Green Lake? 2. What is the elevation of Green Lake on the map? 3. Which corner of the Green Lake map shows the highest elevation? 4. What is the elevation of that corner point on the Green Lake map? 5. Bagley School is adjacent to which index contour? 6. How many churches are shown on the Green Lake map? BLAKE ISLAND The next map shows Blake Island in Puget Sound, a few miles west of Seattle. By now, you have learned how to read that the highest point on Blake Island is between 250 and 275 feet. The contour interval of the map is 25 feet and the index contours are every 100 feet. The numbers "25" and "36" are related to the Public Land Survey System. The next two maps will illustrate some additional interpretations of contour lines. 1. From which direction would it be easiest (least steep) to climb from the shore to the top of Blake Island? 2. What about the map tells us that way would be the least steep? Lab Worksheet Topographic Maps page 7

8 GRAND CANYON This topographic map shows the Isis Temple, a high-elevation (7012 foot) butte in the Grand Canyon, in northern Arizona. You will notice that the contour lines are closer at some elevations (the steep cliffs) and more broadly spaced at other elevations (the less steep slopes). 1. What is the contour interval? 2. Climbing Isis Temple from the south or west, the steepest cliff occurs between which two adjacent INDEX contours? FLORIDA KARST This map shows a sinkhole region, or karst region, in Florida. Note that the hachure marks mean that the contour lines drop in elevation instead of rise. Some of these sinkholes are deep enough to be filled with water to become lakes. 1. What is the contour interval? 2. What is the elevation at point 1 (at the end of the green arrow)? 3. What is the elevation at point 2 (at the end of the green arrow)? 4. What is the elevation at point 3 (at the end of the green arrow)? Lab Worksheet Topographic Maps page 8

9 PART 3: COMPLETE QUADRANGLE TOPOGRAPHIC MAP Use the topographic map to answer the following questions. Refer to the map quadrangles section of the maps Basics page ( 1. What is the name of the map quadrangle? 2. What size quadrangle does the topographic map cover? 3. What fraction of a degree of latitude does the map span? 1/2, 1/4, 1/8, or 1/16? (circle your answer) 4. What fraction of a degree of longitude does the map span? 1/2, 1/4, 1/8, or 1/16? (circle your answer) 5. What is the latitude of the northern boundary of the map? (When writing latitudes, you must write N after the angle if it is in the Northern Hemisphere, or S if it is in the Southern Hemisphere.) 6. What longitude is the eastern boundary of the map? (When writing longitudes, you must write E after the angle if it is in the Eastern Hemisphere, W if it is in the Western Hemisphere.) 7. What is the fractional scale on the map? (fill in the blank) 1: 8. Calculate how many miles in the real world are represented by 1 inch on the map. Note that there are 5,280 feet in one mile, and 12 inches in one foot. (fill in the blanks) ft/mile 12 in/ft = in/mile Now that you know how many inches there are in a mile, you can answer the following question: How many miles in the real world are represented by one inch on the map? (fill in the blanks) in* ** in/mile = miles/in *number of inches in real world represented by one inch on map refer to the fractional scale **answer to previous question Your answer is the number of miles in the real world represented by one inch on your map. 9. How many miles does your map span, east to west from border to border? (One way to determine the distance is to measure it in inches, then multiply the number of inches by the number of miles per inch that you got for the previous question.) Lab Worksheet Topographic Maps page 9

10 10. How many miles does your map span, north to south from border to border? 11. What was the magnetic declination of the map at the time it was published? (Remember to state not only the number of degrees but whether magnetic north was east of true north or west of true north.) 12. If you were interested in a map of the land just southeast of this map, which topographic quadrangle map would you get? 13. What is the contour interval for this map? 14. What is the highest elevation labeled for a peak or hilltop on the map? 15. What is the lowest elevation on the map? (Hint: It may be lower than lowest labeled elevation, in which case you would answer: "The lowest elevation on the map is lower than [the last contour line before that point on the map] and higher than [the elevation of what would be the next contour line down in elevation, which is not seen on the map]). Lab Worksheet Topographic Maps page 10

Laboratory Exercise #2 Introduction to Quadrangle Maps

page - Laboratory Exercise #2 Introduction to Quadrangle Maps A. Introduction to Quadrangle Maps The United States Geological Survey has developed a nationwide series of quadrangle maps that cover small