Physiography of the Earth

Purpose

  1. Discover that earth has bimodal distribution of elevations.
  2. Introduce the GeoMapApp web-based Viewer as a tool for manipulating data.
  3. Refresh memories of the use of latitude, longitude for positioning on a sphere.

Instructions

  1. Navigate to http://web.mit.edu/kenta/www/one/world-map.png and print the world map. How is this map different from ones you've seen most often (look at Greenland, Russia, Siberia, etc.).
    • Label Greenwich meridian, International Date Line, and the equator (label each line).
    • Mark the location of New York, NY and Cairo, Egypt.
      • NYC coordinates: 40.71°N, -74°W
      • Cairo Coordinates: 30.058°N, 31.229°E
    • Estimate the distance between the 2 cities: Construct a right triangle such that the hypotenuse represents the distance between NY and Cairo.
      • Use the difference between the North-South coordinates as one side of your right triangle and the difference of the East-West coordinates as the other.
      • Now convert the values on the sides of your triangles to kilometers. Assume there are 111km for each degree latitude and 91km for each degree longitude.
    • Use an online distance calculator to find the true distance between the cities. (Try http://www.infoplease.com/atlas/calculate-distance.html) Why is your value different from that reported in the online calculator. (You may want to refer to a globe.).
  2. Use the GeoMapApp Viewer to examine color map of world topography.
    • Start GeoMapApp by clicking the icon in the applications folder. Note that you can download this viewer for free on your own computer (recommended) at: http://www.marine-geo.org/geomapapp/
    • Experiment with GeoMapApp's main plotting functions.
      • Maximize the GeoMapApp window for best viewing.
      • Zoom in on the Rocky Mountains, and then zoom back out. Note that it may take a few seconds for the higher resolution map to load! Geomapapp has to query a central computer for each request you give it… If it will not load quickly, try pressing the 'fx' (for 'focus') button on your button menu.
      • Zoom in on the island of Hawai'i (the big island).
      • Add a map scale to your display via the 'view' menu. How far across is the big island? Can you find 5 volcanoes? 6?
      • Click the 'grid' icon on the far right of the icon bar. A 'grid options' window should pop up, giving you many display customization options. Add contours to your view of Hawai'i and play with the illumination angle. What happens when you set the following illumination parameters: Declination 0, Inclination 90?
    • Plot an east-west cross section of the Earth's surface from 180W to 180E at latitude 28S by selecting the "cross-section" tool, clicking on a starting point and dragging the mouse with the button held down to the end point, and then releasing the mouse button. An example profile will be shown in lab.
    • Print out a copy of your profile and label continents and ocean basins.
    • Draw the location of the profile on your 2D world map.
    • What are the "typical" elevations of continents and oceans?

Lab Report

Please note that lab reports in this course are different from those in the climate system course!! There is no need to repeat the lab procedure. Please provide responses to the listed items, remembering to label and annotate all figures. Unless otherwise indicated, questions within the lab are intended to guide your thinking and better enable to answer the questions below

For your lab report, include the following:

  1. Give a one paragraph summary of your major conclusions about continents and oceans. It should contain 10 very general observations you have made about Earth's surface. FYI: in this first exercise, you will be graded only on your observations. In the future, you will be asked to connect your observations to an explanation. It wouldn't hurt to come up with explanations for your observations now though... Possible examples of observations include "there are no visible craters on the Earth's surface" (possible explanation: they existed but have been erased) and "the Alps and Himalayas appear to be part of a more or less continuous and curvilinear chain of mountains" (possible explanation: ???).
  2. Include an annotated printout of your East-West profile. Name the major continents and ocean basins and label the main features (mountain ranges, etc.) within each. You should have at least 5 features labeled, but more is better.
  3. Hand in print-outs of at least three graphs supporting your observations. These may include cross-sections, maps or any other data available in GeoMapApp.
  4. Hand in your world map showing the Greenwich meridian, International Date line and the Equator. Compare your esitimate of the distance from NY to Cairo to that you obtained from a distance calculator. Include a brief explanation of why your estimated distance is different from the distance between these 2 cities on the Earth.

Updated February 15, 2008
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