U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
 
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FOR THE CLASSROOM

Picture of Mining Vehicle

EROSION LANDSCAPES
Objective:
In this activity, students will learn the importance of revegetating areas that have been reclaimed after mining. Students will compare the movement of water and the degree of erosion over slopes with and without plant cover.

Materials: For this activity you will need

  • two large plastic trays (such as kitty litter boxes);
  • a portable hand drill with 3/8" drill bit;
  • a watering can with a sieve style head;
  • soil mix (soil, sand, and gravel);
  • grass seed (rapid growth);
  • two coffee filters and coffee filter holders;
  • two large empty coffee cans;
  • duct tape;
  • two empty juice cans or cartons of about 240 mL capacity;
  • wooden blocks to support the trays;
  • and water.

Artist's depiction of erosion activity

Procedure: Drill a small hole at the end of each tray at the center just above a line 2.5 cm from the top. Have students fill the two trays with soil mix to just below the drilled holes. Pack the soil mix slightly, but don't overdo it.

Leave one tray as it is, containing just the soil. For the second tray, ask students to spread evenly a thin layer of rapid-growth grass seed over the entire area. Have them gently press the seed into the soil, then place the seeded tray on a sunny windowsill.

Using the watering can, they should gently water the grass seed daily. When the grass is firmly rooted, you are ready to conduct the experiment.

Place both trays side-by-side on a table with the ends with the holes lined up near the table edge. Place a wooden block under each tray at the end opposite the one with the hole. Place a bench at the end of the table to serve as a platform for two coffee cans, which will serve as water catchments for water draining from the two trays. Rest a coffee filter holder inside each coffee can. Place a filter in each filter holder. Using waterproof tape, attach small "troughs" made from empty juice cartons or cans to the ends of the trays to guide the runoff from the trays to the filters.

Now, using the watering can, have a student gently pour about 500 mL water over the tray containing just the soil. Have students record their observations. Measure and record the volume of soil that drained into the coffee filter. Next, pour the same quantity of water over the tray planted with grass seed. Students should record their observations and measure the volume of soil runoff. Encourage students to compare the movement of water through sites that have plant cover to those that do not.

Discuss how rivers and other bodies of water can be affected by surrounding areas with and without plant cover. Have students pour some sand or soil into a clear glass of water. Note how materials begin to settle out. Discuss how a stream or lake could be affected by an accumulation of sediment. High levels of sediment can adversely affect aquatic plants and animals. Relate your discussion to mine reclamation and the importance of revegetation to control stream sedimentation.

 

Extension: Introduce other variables (such as different slope angles, different rates of watering during germination, different compaction, and different percentages of vegetative cover) and record the results.

For a simpler activity: Have students make a mountain of soil in the middle of a pie tin. Next, have the students squirt water on the mountain and record their observations. Next, have students rebuild their mountains, this time adding small stones or pebbles to the slope of the mountain. Once again, have students squirt water on the mountain and observe and record the effects. Do the stones have any effect on the erosion? Finally, have students place small twigs onto the slope of the mountain. The twigs will represent trees. For a third time, have the students squirt water on the mountain and observe and record the effects.

 

Extension: Have students inventory their school grounds to identify areas likely to have erosion problems and design a landscape to control erosion.

 

NATURE'S PUZZLE
Natural systems are complex arrangements of physical components (geology, topography, soils, climate and weather), material cycles (water, for example), and biological components (plant and animal communities). When people change a piece of the natural landscape through mining, the effects involve many components of the Earth's natural systems.

Objectives: In this activity, students will relate the challenges of restoring an ecosystem to those of piecing together a simple puzzle. Students will describe the challenges of restoring a natural environment altered by natural and human forces.

 

Materials: For this activity, each small group of students will need

  • a puzzle pattern
  • glue,
  • a ruler,
  • drawing materials,
  • old magazines,
  • scissors,
  • and poster board.

 

Procedure: Show students pictures of altered environments. Discuss how natural events (earthquakes, volcanic eruptions, floods, and fires) and human activities (road paving, mining, deforestation, dam construction, draining wetlands, and causing fires) affect natural habitats. What do students think should be done? Explain that the best solution is prevention wherever possible, and the next best solution is restoration. Together, list reasons for restoring systems (for example, erosion control, flood control, wildlife preservation, aesthetics, and the improvement of water quality).

Divide the class into small groups, and distribute to each group a copy of a circular puzzle patterns about 30 cm in diameter, one divided into piesliced pieces and the other into small square pieces in a waffle-like grid (the puzzle can be more or less complicated by number and shape of the pieces depending on the time available for the activity and the students' skill level). Have students glue the puzzle pattern to the backside of the poster board. Distribute old magazines and have students locate nature scenes, preferably ones showing water. Tell them to cut out a picture and glue it to the front side of the poster board.

Have students reverse the poster board and carefully cut it on the lines of the pattern. Instruct students to scatter the puzzle pieces, explaining to them that this represents a natural area that has been disturbed.

Discuss with students the difficulties of putting ecosystems back together again. Specifically discuss food, habitat, and shelter for the animals, as well as habitat for the plants.

Tell students to arrange their scattered puzzle pieces face down. Have them switch places with another group, and ask the students to try to put the puzzle pieces back together again without turning the pieces over. Have the students tape the puzzles together and turn the puzzles over. Some of the pictures may be accurately reconstructed, but because of identically shaped puzzle pieces that can be interchanged (without the visual clue of a picture to guide students), some may not. This emphasizes the point that for an ecosystem to function the parts must be put together properly, and that missing parts make it difficult to restore. The thousands of geological disturbances resulting from historic hardrock mining in the West are a good example of the difficulties of reconstructing disturbed ecosystems. For example, at the Chalk Creek site in the Rocky Mountains, scientists working on restoration efforts have determined that even with a total cleanup, it could take decades to see complete restoration of water quality there. Additional causes of contamination are likely to become apparent only after cleanup of obvious sources.

 

SOIL SAMPLES
Soils are often classified by texture, which is determined by the amounts of clay, decomposed organic matter, sand, and other components they contain. The ratio of these components in relationship to other environmental factors helps determine how well soil can sustain plants and withstand erosion, which plants will grow well, and whether the soil can support development. An important reclamation practice is the replacement of topsoil (the surface layer of soil). Topsoil is stored prior to mining in anticipation of the rehabilitation of the disturbed surface. In some cases other soil layers are segregated as well. After the mining ceases, topsoil and other soil layers are respread to assist in revegetation.

 

Objective: The following activity will help students gain an understanding of the relationship of soil quality and vegetation and the value of topsoil replacement as a reclamation practice.

 

Materials: For this activity, each small group of students will need

  • four containers of about 240 mL capacity,
  • about 200 mL each of clay, sand, small rocks, and topsoil,
  • and grass seed (rapid growth).

 

Procedure: Students should fill each container with a different growing medium (the clay, sand, small rocks, and topsoil) and plant a few grass seeds in each one, labeling the containers accordingly. When watering the seeds, students should measure and use the same amount of water for each container. Keep a record of the growth rates in each container. In which soil does the grass grow best? In discussing results, explain that different plants grow better in different types of soil, depending on texture and nutrients, which come from minerals and decomposed organic matter.

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Last updated: 11-13-2009