Colorado’s Geography: Mapping Our Past
Teacher Resources for Activities PG-1, PG-2, PG-3
Colorado’s Physical Geography:
The Continental Divide, Precipitation Patterns, and Life Zones
Main Learning Objectives
In the first activity, students learn the definition of the Continental Divide and its
location in Colorado and the Western states.
In the second activity, students learn how the mountains affect the state’s
precipitation patterns.
In the third activity, students learn where the state’s five life zones are located
and predict which plants and animals survive in each zone.
Colorado Geography Standards
1.2 Students develop knowledge of Earth to locate peoples, places, and
environments.
3.1 Students know the physical patterns that shape Earth’s surface patterns.
3.2 Students know the characteristics and distributions of physical systems of
land, air, water, plants, and animals.
Essential Concepts
The Continental Divide is an imaginary line that follows ridges and high points
through the mountains, dividing the rivers that flow west to the Pacific from those
that flow east toward the Gulf of Mexico and the Atlantic Ocean. Every continent
has at least one divide (except Antarctica, which has no surface rivers). Divides
separate rivers into basins or watersheds, which are areas of land defined by
the ridgelines surrounding them. All surface water in that area originates from
runoff from the slopes below the divide’s ridges. Historically, the Continental
Divide is also important because river valleys were used for transport in the
mountain west and the Divide was often a major barrier to human interaction. In
a related activity (Water Resource Development), students can see how
Coloradans have built tunnels and other structures to move water through the
Continental Divide.
The mountains on Colorado’s western slope get a lot more precipitation than the
Eastern Plains because the clouds are blocked as they head west over the
mountains. In middle latitudes, in both the northern and southern hemispheres,
the prevailing airflow is from west to east (called westerly winds). As moist air
in clouds is forced over the mountains, the air gets cooler and the moisture
condenses and precipitates. Therefore, the slopes facing the prevailing winds
(the western slopes of the Rockies and other ranges in the West) get most of the
precipitation. This process is called orographic precipitation (“orographic” just
means caused by mountains”). After the air crosses the mountains and reaches
the Eastern Plains, it has lost most of its moisture. This creates a drier area, or
rain shadow, on the east (leeward) slopes of all mountain ranges in the Western
United States.
Colorado’s five life zones are defined mostly by elevation. These zones have
typical patterns of temperature and precipitation and help to determine which
plants and animals can survive. In Colorado, the lowest life zone is below 6,000
feet. This is the Plains life zone, which is dominated by grasslands (prairie).
Above that is the Foothills life zone, between 6,000 and 8,000 feet. This zone is
mainly Ponderosa pine forest and woodlands, with some Douglas-fir trees on
moister slopes. The Montane zone (8,000 – 10,000 feet) has denser forests
dominated by Douglas-fir and Lodgepole pine trees. Next highest is the
Subalpine zone (10,000 – 11,500 feet), which is much cooler and wetter. In
Colorado, the main trees in these forests are Subalpine fir and Engelmann
spruce. Above 11,500 feet is the Alpine zone, which is a treeless, tundra
environment. The border between the Subalpine and Alpine zones is called the
treeline. Its position is higher on north-facing (shady) slopes than on southfacing (sunny) slopes.
Materials
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Computer/internet access (http://geography.unco.edu/mapco)
Worksheet/copies
Pen/pencil
Colored pencils
Worksheet PG-1
Name _____________________
Open Activity 1: The Continental Divide (the internet link says: Activities PG1, PG-2, and PG-3)
1. The Continental Divide is an imaginary line that follows the highest points of
the mountains. All the rivers on the west side of the Divide flow toward the
Pacific Ocean and all the rivers on the east side of the Divide flow toward the
Atlantic Ocean. Looking at this map of Colorado’s major rivers and some cities,
predict where the Continental Divide is. Draw a red dotted line to show your
prediction on the map below.
example
Why did you predict this location?
Try to get kids to draw lines separating the major drainage basins. (It may sound
a bit silly—but sometimes we have to remind students that water flows downhill.)
Accept any answer at this stage.
2. Make Visible the Mountains layer and then Refresh Map. Does this
information change your prediction? Yes or no. If so, draw a new red dotted
line on the map below.
Why did you predict this location?
Addition of the mountains may help students fine-tune their prediction. For
example, in the southwest the line might shift a bit to the right to take into
account the San Juan Mountains. It is usually the high mountain areas that will
represent the dividing line (continental divide). Be sure students do not draw
lines that cross rivers – the concept is that the ridges of the Divide separate the
rivers into distinct areas (called watersheds or basins).
3. Make Visible the Continental Divide layer to check your prediction. On the
map below, shade the eastern slope yellow and the western slope green. Put a
blue dot where you think your community is. Do you think you live on the eastern
or western slope? Answers will vary; accept speculation.
4. Make Visible AND Active the Communities layer. Refresh Map. Select
“Query” (the button with a red “?”). Under “Field” select Name. Under “Value”
type in the name of your community. Click on “Add to Query String.” Click “on
Execute.” Your community will show up as a yellow dot. Be sure students spell
name exactly.
5. Put a yellow dot on the map above to show your community’s location. Were
you correct about your prediction of being on the eastern or western slope?
Answer depends.
6. Turn off ALL layers. Then Make Visible the Western States, Continental
Divide, and Western Rivers layers. Refresh Map AND then click the
Zoom
to Full Extent button. You should see a map like the one below. Colorado is one
state in the Rocky Mountain region. The Continental Divide runs north all the
way into Canada and south into Mexico. On the map below, predict where the
Continental Divide should be across the other states. Draw the line in red.
Make sure the line splits the river basins.
example
Turn in this page to your teacher. This is the end of Activity PG-1.
Worksheet PG-2
Name _____________________
Open Activity 2: Precipitation in Colorado (the internet link says: Activities
PG-1, PG-2, and PG-3)
1. Make Visible the Mountains and Continental Divide layers, and Refresh
Map. Looking at the Divide, mountains, and rivers in Colorado, where do you
predict our state gets the most precipitation (rain and snow)? Where do you
think it gets the least precipitation? On the map below, shade the areas you
think are the wettest in blue and the areas you think are the driest in yellow. You
don’t need to shade the entire map. Remember wet means a lot of rain AND
snow!
2. How did you decide which areas would be wet?
A wide range of maps will be produced for this question. Steer the students
toward identifying wet areas in the mountains and dry or semi-dry areas in the
Plains and western Colorado (although we’ll see this isn’t perfect). Having
students think in terms of where forests are and are not may be helpful. A look at
the actual Internet map shows Wet (above 20 inches a year), Semi-arid (10-20
inches a year), and Dry (10 and less) areas. It might also be useful to pick out
one of the “dry” areas such as the San Luis Valley in Southern Colorado and
discuss why that area is so dry (surrounded by mountains, creating a rain
shadow effect).
3. How did you decide which areas would be dry?
See above discussion. Talk about rain shadow effect. Check out:
http://www.iusd.k12.ca.us/uhs/cs2/rainshadow_effect.htm
4. Make Visible the Precipitation Zones layer and Refresh Map to check your
prediction. Click the
Toggle between Legend and LayerList button to see
what the different colors mean for Precipitation Zones. Define these below.
Color:
yellow
green
blue
Meaning:
arid (dry)
semi-arid
wet
5. Which areas of Colorado receive the most precipitation?
The mountains do, especially near the highest points along the Divide. Explain
the concept of orographic precipitation. A useful web-site is at:
http://en.wikipedia.org/wiki/Precipitation_(meteorology)
6. Which areas of Colorado receive the least precipitation?
These are rain shadow areas, such as the Eastern Plains. Also, North Park
(e.g., Walden), Middle Park (e.g., Granby), South Park (e.g., Fairplay), and the
San Luis Valley (e.g., Alamosa) are all surrounded by mountains and also in the
mountains’ “rain shadow.”
7. Is most of the state wet, semi-arid, or arid? Semi-arid
8. Make Visible AND Active the Communities layer, then Refresh Map. Use the
“Query” button exactly as you did in Activity PG-1 to find your community’s
location. This will show your town in yellow.
Do you live in a wet, semi-arid, or arid region? Answer will vary.
This is the end of Activity PG-2.
Worksheet PG-3
Name _____________________
Open Activity 3: Colorado’s Life Zones (the internet link says: Activities PG-1,
PG-2, and PG-3)
Teachers are strongly urged to do a little refresher on life zones. This first
website comes closest to the description appropriate for this activity:
http://academy.d20.co.edu/pes/websites/lifezones_scaffold.html
Be aware that there are varying ways to describe life zones. Other websites that
might be of value include: http://www.4corners.net/ccyc/pl2.htm
http://www.mesastate.edu/schools/snsm/shideler/ecosys.htm
Colorado can be divided into five life zones going from lowest to highest
elevation: Plains, Foothills, Montane, Subalpine, and Alpine. The life zones are
defined by elevation (how high the land is above sea level).
1. Make Visible the Mountains layer, and Refresh Map. On the map below, try
to predict where each life zone is. Color the Plains yellow, the Foothills orange,
the Montane brown, the Subalpine dark red, and the Alpine gray or white.
Make Visible the Life Zones layer and Refresh Map. Click the
Toggle
between Legend and LayerList button to see what the different Life Zone colors
mean. Check your prediction.
This will be a challenge for kids to create an accurate map! However, they
should get the basics: the further INTO the mountains the higher the zone (Alpine
or Subalpine), and the further AWAY from the mountains the lower the zone
(Foothills or Plains).
2. Make Visible AND Active the Communities layer, then Refresh Map. Use the
Identify button to find your hometown or a nearby town or city. Which life
zone do you live in? Answer varies.
3. Which Life Zone appears to occupy the MOST land in Colorado? Plains
The least? Alpine
4. Predict the Life Zone that you would expect to see in Colorado’s eastern
neighboring states. Probably the Plains zone.
5. Colorado is the beginning of the Great Plains region.
6. Predict an animal and plant that could survive in each life zone. Use
reference materials to check and correct your predictions.
Consider having kids go to the following website:
http://academy.d20.co.edu/pes/websites/lifezones_scaffold.html
or, http://www.bvsd.k12.co.us/schools/coalcreek/wildlife/wildlife_index.html
Source: , http://www.bvsd.k12.co.us/schools/coalcreek/wildlife/wildlife_index.html
This is the end of Activity PG-3.