River Formations

We completed a recent experiment on the formation of rivers. Each group had to choose two different factors that contributed to river formation, develop a hypothesis based on each factor, and conduct an experiment for both. My group chose erosion and animals as our two factors.

For erosion, my hypothesis was, "If water passes over land repeatedly, a riverbed will form." Our independent variable was water flowing over land continuously, and our dependent variable was the land eroding away. To test this hypothesis, we used diatomaceous earth and water as our materials. The first step was to prepare the diatomaceous earth by mixing it with water and draining away any excess water. Next, we propped up the tub containing the diatomaceous earth with a book. We did this so the water would flow from the top of one side to the bottom of the other. First, we tried just pouring the water over the land once, and a small stream formed. When we poured the water over repeatedly, a larger riverbed formed. My hypothesis proved to be correct, because a river formed after water was repeatedly poured over the same piece of land.

Animals was the next factor we tested. My hypothesis for this experiment was, "If animals create a path to a water source, a river will form." This time, our independent variable was the ability of animal paths to create rivers, and our dependent variable was the tracks eroding and water building up to form a river. We used the same materials as before; diatomaceous earth and water. Like before, we started by preparing the diatomaceous earth and draining any water. Next, we made a small "pond" in the tub by making an indent in the diatomaceous earth and filling it with water. This was our water source. Next, we made an "animal path" to the water source. We did this by pressing our fingers and knuckles into the d. earth in the form of a path to the water source. Once we had propped up the tub again, we poured water down the path to the water source. Sure enough, the path eroded away and a river to the water source formed. As a control, we flattened out the path we had made and poured water down to the pond again. This time, a river did not form. Again the hypothesis proved to be true; if animals travel to a water source enough, a river can form.