Geol 301 Fall 2006Visualizing the Earth: Topography and Topographic MapsConcepts and Terms:- Visualizing 3D in 2D- Contour Interval- Contour lines- Gradient- Index Contours- Latitude and Longitude- Profiles- Relief- Rule of “Vs”- Scale- Finding Topographic Map and other visualization of the EarthPart 1. Computer assisted visualization of 3D in 2DMaterial adapted from: http://reynolds.asu.edu/From this main link choose: Visualizing Topography from the side menu and then choose click to enter. Background: Topographic Maps Module Student GuideIn this module, you will learn about topographic maps – one method of showing thevarying elevations of an area using lines (contour lines) that represent a single elevation. You will be able to view movies showing three landforms: hill, valley, and cliff. For each landform you will first see its topographic map and then interact with movies showing each landform’s three-dimensional features.The purpose of this module is to help you learn to visualize the three-dimensional surfaceof a landform from two-dimensional topographic maps. Observations of students readingtopographic maps have shown that students struggle with this interpretation exercise. Themovies that are included in this module helped those students to improve their map-reading, interpretation, and visualization skills.Some of the movies included in this module are virtual reality (VR) movies and allowyou to click-and-drag the mouse inside the image to change features of the movies. Note it is important to wait to click and drag until after the Quicktime file is completely loaded. Above each movie, arrows will indicate the direction(s) you can move the mouse and text will indicate what changes will occur as you drag the mouse in each direction. Other movies are self-playing, and after a short pause on the screen, they will beginplaying without you having to do anything. Once these movies reach the end, they will repeat from the beginning.There are several different types of movies in this module.--Tilt and rotate. In the VR version, you can click-and-drag the mouse to 1) rotate themovie 360° (by clicking and dragging side-to-side) and 2) tilt the landscape on itsside to view elevation differences (by clicking and dragging up and down).--Shading. These movies allow you to watch shadows lengthen and shorten acrosssurface features and show you how shadows would change as the sun rises and sets.--Flooding. These movies allow you to flood a given landscape and watch how waterfills a terrain.--Profile-slicing. These movies allow you to cut into a landscape from front to back tosee how profiles (side views) of the landscape change and how topographic mapswould look if viewed from the side.The research group that developed this module feels the best way for you to learnabout topographic maps is to play with the movies we’ve made for this module. For you to get the most out of this, you might have to look at each movie a few times. Before you start the module, make sure you have the worksheets handy! We included these to help you keep a record of your answers to questions, observations, and progress as you go through this module.Instructions: Work through the Visualizing Topography module on the computer. Put your observations and answers in the appropriate spaces below.1. By now you have a picture in your mind of what this landscape looks like. In the spaceprovided below, write a description of this landscape so that someone who had not seen itbefore could imagine it in their mind.Landscape Description:2. By now you have a picture in your mind of what this landscape looks like. In the space provided below, write a description of this landscape so that someone who had not seen it before could imagine it in their mind.Landscape Description:3. By now you have a picture in your mind of how this landscape floods. In the space provided below, write a description of this landscape so that someone who had not seen it flood before could imagine it flooding in their mind.Landscape flooding description:4. Try to envision walking from G to H., especially when you are going up hill and when you are going downhill. Sketch the profile from G to H in the space provided.Profile from G to H:Part 2. Examining the Harrisonburg Quadrangle topographic map1. What is the relief (in feet) of Massanutten Mountain? Relief is the difference in elevation between the highest and lowest points in a region. (How can you easily identify the highest peak of this mountain?) 2. What is the latitude and longitude of Massanutten Peak? (Interpolation between provided reference latitudes and longitudes along edge of map is key.)Latitude = Longitude = 3. What is the distance of the stream that flows from Massanutten Mountain to Massanutten Caverns? (Think - how can you measure this curved feature?)Distance in feet:Distance in miles: 4. What is the gradient of the stream that flows from Massanutten Mountain to Massanutten Caverns? Gradient = how steep or gentle the slope is. From math classes remember that slope = rise/run. The units are typically feet/mile or meters/kilometer.Qualitative description: Quantitative measurement:5. Describe the shape of the contour lines as the cross the stream you examined in #3& 4. Specifically relate this pattern to the flow direction (e.g., downstream, upstream) of the stream. This pattern can be generalized for all streams on topographic maps and is useful to quickly determine the flow direction of a stream.6. Try envisioning walking in a straight line from Massanutten Caverns up to the topof the ridge (let’s say to the “M” in the word Massanutten printed along the ridge).Sketch the profile of the topography you would transverse.7. The profile you just sketched can be drawn more accurately and to scale by using the elevation information that the contour lines provides along the transverse. Usethe index contours only and the attached graph paper to plot a profile that is to scale.8. The town of Harrisonburg decides to build a new dam and reservoir for recreationand flood control. The proposed dam location is marked as a dark thick line on theattached photocopy of part of the Harrisonburg Quadrangle. (Refer to your original map to see the colors, but write only on the photocopy.) If the top of the dam came to an elevation of 1300 ft above sea level and the reservoir filled with water to the very top of the dam, shade in the land that would be covered with water. (How will the