Assignment: Topographic Maps

Module 1 Assignment

Topographic Maps

A picture of John Wesley Powell, Director of the USGS 1881-1894. Quote showing: A government cannot do any scientific work of more value to the people at large than by causing the construction of topographic maps of the country. Facts showing: U.S. Geological Survey: a History of the National Program for Topographic Mapping (1884–2009) and Continuing Innovation into the Future. Topographic maps became a signature product of the USGS because the public found them — then and now — to be a critical and versatile tool for viewing the nation's vast landscape. From the 1880's until the advent of computers and geographic information system (GIS) software, topographic maps served as the essential instrument for the integration and analysis of place-based information. In the last quarter-century, advancing technologies have transformed topographic mapping science from the printed product to digital data and on-line based applications. Along with highlighting a legacy of more than 130 years of topographic mapping, the National Geospatial Program of the USGS is proud to release a new type of digital topographic map and the new interactive viewer for The National Map.

Figure 1.

Instructions

NOTE: For all of the following figures, assume North is up.

  1. (2 pts) The following topographic map is from a coastal area and features an interesting geological hazard in addition to the ocean. Using a contour interval of 40 meters, label the elevation of every contour line on Map 1 below. (Note: elevation is meters above sea level, which makes sea level = ___m)
    Map 1.
  2. (4 pts) Imagine you are a geologist for the United States Geological Survey. You are tasked with creating your own coastal topographic map, so you hike around the area with a GPS receiver (Global Positioning System) and every so often you record your position along with the elevation in meters at that point, which results in Map 2 below. Complete this map by adding in the contour lines using a contour interval of 100 meters. Draw the contour lines so that they are continuous (do not die off ), and either continue off the map or form an enclosed circle (look at the topographic map in Question 1 for an example). More often than not, your contour lines will fall between the GPS points on your map, so do your best to determine the contour line positions.
    Map 2.
  3. (1 pt) What is the contour interval on Map 3 above?
    Map 3.
  4. (1 pt) What is the regional relief on Map 3 above?
  5. (1 pt) Using the contour lines on Map 3, which area along the red line is steeper— A to B or B to C? Explain how you came to this conclusion.
  6. (2 pts) What is the gradient from A to B and B to C on Map 3? Show your work.
  7. (2 pts) Drumlins can be used to determine the original direction of flow in a glacier, with the glacier originally moving toward the shallower side of the structure and then retreating in the opposite direction (see illustration below).Using your previous answers from Questions 5 and 6 above and the illustration below, what direction was the glacier traveling originally traveling, before it retreated?Explain your answer. (Remember that North is up on the map.)
    Map 4.
  8. (4 pts) Construct a topographic profile from A to A’ on the graph paper below.
    Map 5
  9. (3 pts) Based on the scale you choose for the topography (vertical axis) in question 8, calculate the amount of vertical exaggeration on the topographic profile you constructed above. Show your work.