1.3 Topography and Our National Parks

How did Yosemite inspire the institution of the National Park System?

Step 1: Go to the ArcGIS Online map, Topography and Our National Heritage, and explore the map. Investigate the pins that show on the map.

As urbanization increases, many argue that we need natural areas for preserving the natural ecology, for rest and relaxation, and for reconnecting to global systems. These areas can remind us to live more sustainably.

  • What do the smooth brownish parallel lines around the map represent?
  • What do the blue squiggly lines represent?
  • The most visible landform on the map is a valley, where the elevation numbers get smaller toward the Merced River. (T/F)

What do the brown topo lines tell us about the landscape?

Step 2: Click the button, bookmarks, and select Half Dome.

Topo lines rarely ever touch or cross That is because each line is a different elevation. That means no point can be two different elevations. The only rare exceptions are cliffs or overhangs. Half Dome is a large and steep-sided hill referred to as a mountain.

  • What patterns do topo lines make around hills and mountains?

When you get to the edge, what does it look like?

Step 3: Click the button, Bookmarks, and select El Capitan.

  • What is the pattern of topo lines for very steep areas like this cliff?

Step 4: Click the button, Bookmarks, and select Camp Ground.

Step 5: With the Details button underlined, click the button, Show Contents of Map (Content).

Step 6: Turn off the layer, USA Topo Maps.

  • Why does this area not have concentric circles or parallel lines that are close together?

Some topo lines are thicker than others and are called index contours.

  • What do index contours have periodically along their lengths that other lines do not?
  • What is the elevation of this area in feet?

Elaborate: How do you show tall things on flat paper?

Step 7: Change the Basemap to Imagery. Turn on the layer, USA Topo Maps. Throughout this assignment, turn on and off the USA Topo Maps to compare the topo map to satellite imagery.

Step 8: Zoom to Half Dome, and then find two index contours close together, with clearly marked elevations.

  • How many lines are there between the two index contours?

A contour interval is a vertical distance between contour lines. Determine the contour interval. Take the difference in elevation and divide by the number of intervals. For this map, the contour interval is 40 feet.

  • What is the elevation of the topo line atop Half Dome?

Step 9: In the bottom left, there is a scale bar. Us a sheet of paper to copy the distance shown on the scale to the paper (it should be 0.2 miles). Click the button, Measure. Click the Distance button and select miles as the units.

  • Measure the distance from the top of Half Dome to where the trail meets the river. How far is it?

How steep would the Half Dome trail be?

  • Looking at Half Dome, which side of the hill would be easiest to climb?
  • Which stream would be less strenuous to hike from the campground: a couple of miles up Tenaya Creek to the north of Half Dome, or a couple of miles up the Merced to the south of Half Dome?

Step 10: Pan to the south until you find the Merced River.

  • Which way is the stream flowing?

Step 11: Click on Bookmarks and select Yosemite.

  • Which of the upriver canyons might be more likely to flash floods?

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