Melting Mountains: Do Mountains Shrink in the Heat?
Purpose or Problem
Mountain material is lost to erosion every spring as snow and ice on mountain peaks melt. We will attempt to determine if the rate at which the ice melts (due to temperature) has an effect on the amount of material lost to erosion.
Alluvial deposits are the materials (soil, rock, debris, and so forth) that have accumulated from being transported by moving water. Alluvial formations are created at the deltas of rivers, as material is deposited by the currents of water.
Every spring, snow and ice on mountains begin to melt. As gravity and the steepness of mountain sides accelerate the flow of water, materials from the mountain are carried along with the water. If spring temperatures are warmer than normal, will this cause more material to be carried off the mountain than if temperatures were more moderate? If so, mountain erosion caused by melting snow and ice would be in direct relationship to temperature.
Hypothesize that more alluvial material will be deposited by melting ice when the temperature increases.
- Two plastic gallon milk jugs
- Two Styrofoam trays
- Two 6-inch-long pieces of 2×4 lumber
- Two cups of very fine sand
- Use of a freezer
- Gram weight scale
- Kitchen measuring cup
- Heat lamp
Two model mountains with melting ice will be set up, with one melting at a much more rapid rate. Held constant in the experiment will be the quantity of sand, ice, and the slope of the runoff. The variable will be the temperature.
Find two small Styrofoam trays. Styrofoam trays are often found in grocery stores with ground beef, veal patties, and other meats packed in them. With scissors, cut the lip off one end of each tray.
Weigh one of the Styrofoam trays on a gram weight scale, and then fill a kitchen measuring cup with very fine sand. Pour the sand onto the Styrofoam tray, positioning it at the center of the tray. Weigh the tray with sand. Subtract the weight of the tray (the tare weight) to find the weight of the sand.
The second tray must be filled with exactly the same quantity of sand as the first tray. Weigh the second Styrofoam tray. Pour a measuring cup of fine sand onto the center of the tray, and then place it on a scale. Subtract the weight of the tray. Add or take away sand from the tray until the second sand pile weighs the same as on the first tray.
Manipulate the sand on both trays until both piles of sand are about equal in size and shape. Use a ruler to measure the height of each pile.
Carefully, using scissors, cut off the bottom part of two plastic gallon milk or water jugs. Cut about 1½ inches up from the bottom, leaving small plastic bowl-like containers. Fill each jug bottom with water to a depth of 1 inch. Place in a freezer.
When completely frozen, remove the two 1-inch slab ice cubes from the plastic jug bowls.
Use a piece of 2×4 wood (or several books stacked on top of each other) to tilt the tray with sand. Position the cut-away end of the tray at the bottom of the slope, and rest it in one of the plastic jug bowls. This will capture any runoff water and sand that is carried down. Carefully set an ice slab on top of each sand pile. This will create a model of melting ice on top of a mountain.
Place the whole device in a cool location somewhere in your home.
Make a second device with the other tray, sand, ice, 2×4, and bowl. Set this one in a place where a heat lamp can be safely positioned over the top of the ice. You can use an infrared bulb, available at pharmacies or possibly from your school science teacher, as a heat lamp.
When the ice on both trays melts completely, remove the two plastic jug bowls. Let the water collected in them evaporate. Then, using a gram weight scale, weigh the remaining particles of sand in each bowl. Was more sand deposited from the heat lamp mountain?
Write down the results of your experiment. Document all observations and data collected.
Come to a conclusion as to whether or not your hypothesis was correct.
- Repeat the previous experiment, but this time, use coarse particles of sand. Hypothesize that not as much material will be deposited because of the bigger size of the particles.
- How does pitch (the slope of the runoff) affect erosion?
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