Breaking the Trail

How is the Iditarod race route over time and today shaped by the forces of nature?

Geography, Geology, History, Science

The Iditarod Trail Sled Dog Race commemorate the 1925 dog teams that rushed serum to Nome to save the people there from dying of the diphtheria disease. At the time the 20 mushers and their dogs ran what was the mail route then from Nenana to Nome. When the Iditarod Race founders initially decided to create a race in 1973, they wanted to race from Anchorage to Nome over a distance of more than 1,000 miles (1609 km).  Villages were used as checkpoints along the way so that mushers could resupply and rest their teams on the long journey. It is not the exact route for the entire way, but both routes carve way across Alaska’s wild terrain — across three mountain ranges — by following the path of least resistance; a path that over time has been shaped by forces of gravity and water, in all its shapes, moving across earths crust shaping the land. What is the connection between geology and the Iditarod Trail today?

Scroll down for activity! Or click to download Breaking the Trail Activity (PDF)

ACTIVITY

Procedure

PART A

1) Have students locate Anchorage and Nome on a map of Alaska (use GoogleEarth, if available). The shortest distance between two points is a straight line. Draw a straight line between Anchorage and Nome. In GoogleEarth, save this line in your My Places folder. This is not the route that the Iditarod Trail follows. Why do you think the race trail does not follow this straight line?

2) Take a closer look at the straight line between Anchorage and Nome. What sorts of land does this line travel over? (Path should cross Cook Inlet, Susitna River, Alaska Range, Kuskokwim River, Kuskokwim Range, Yukon River, Nulato Hills, Norton Sound)

3) Use the Elevation Profile function in GoogleEarth for your straight line path (Fig 2). How much elevation gain and loss does this route include? (roughly 59,000 feet) Identify the three primary mountain ranges that are climbed (Alaska Range, Kuskokwim Range, Nulato Hills) on the elevation profile.

4) Using the latitude-longitude information provided for the Iditarod Trail checkpoints, enter each checkpoint into GoogleEarth as a point (Fig 3). How closely do these checkpoints match your straight line route? What are some reasons that the race route varies from the direct line route?

5) Download the race route Excell document “northern route.xlxs). Overlay the race route onto the map between Willow and Nome. (The ceremonial race start in Anchorage is no longer considered part of the official race route.) Zoom in and look at the race route layout. What sort of land does this route cover?

6) Use the Elevation Profile function in GoogleEarth for the Iditarod route. How much elevation gain and loss does this route include? Identify the three primary mountain ranges that are climbed on the elevation profile. What differences do you notice between this route and the straight line route you created? What advantages does each route have?

7) Based on what you can observe by the Iditarod Trail route, what relationship does cross-country travel routing have with the landforms in the environment? (Students should be able to identify that many routes follow rivers, which are flowing through the path of least resistance. Point out to the students that in Alaska (and many other areas too), the rivers are flowing in areas where glaciers have carved valleys in mountain ranges.)

PART B.

8) Individually or as a class, read “Ch-Ch-Ch-Changes” on the site, describing Earth’s landforms being part of a dynamically and constantly changing system and summing up some of the most prominent processes that alter the surface of Earth.

Although rivers may have a distinct channel that they move in at any point in time, they tend to move through winding sideways erosion (meander) through a wide flood-plain area. Students watch the videos on river meander development listed.
http://serc.carleton.edu/details/files/19164.html
http://serc.carleton.edu/details/files/19080.html

Have students estimate the increase in the overall width of area that is impacted vs. the channel width. (Students may use rulers to measure, graph paper, or develop algebraic formulae, depending on ability.)

9) Using GoogleEarth, as a class or individually zoom in to the area around the Shageluk checkpoint (this checkpoint was mapped in Part A.) Find the city boundary for Shageluk in GoogleEarth in the US Government layer folder.

Share with students that in 1966, the village of Shageluk was relocated to its current location from its original location about 2 miles (3 km) to the north. The air strip is still in the location of the old village. Based on the aerial photography shown in GoogleEarth, why do they think the village had to be moved? What types of landforms can be seen in the aerial photography that would support the conclusion?

Share how vegetation can sometimes be a good indication of underlying land conditions in aerial photography. Look at the vegetation in the Shageluk area. What do can be observed? Why are the coniferous trees located only in the southeastern corner of the city limits? (Coniferous plants prefer more stable and well-drained soils; the area with the treed vegetation appears to be higher ground associated with a ridge of hills east of Shageluk.)

Zoom to the city boundaries for Shageluk in GoogleEarth. Estimate the percentage of the city limits area that appears to be impacted by flooding and river channel meandering, based on your observations of the landforms in the aerial photography. (Shageluk is approximately 12 square miles (31 km2) in area.)

10) Next zoom in on the location of the current village of Shageluk. Based on the landforms you see, does it appear that the new location is less flood-prone than the original location? What evidence supports the conclusion? Does it appear that the entire area of the relocated village is out of flood danger? If you were going to move to Shageluk, what area would be best to live in to avoid flooding dangers?

11) Ask student what populated areas near your location are prone to flooding? (Students may need to research news stories to find locations.) Look at this location in GoogleEarth – can any landforms related to fluvial geomorphology be found in your area? Have the students debate the pros and cons of relocating this populated area near their location. Be sure to include economics, logistics, cultural, and property ownership topics.

River Meanderings

Iditarod Route (xlxs document)

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