47. Compare and contrast valley glaciers and ice sheets. (2 points)
48. List two human activities and two natural events that can cause a large increase in the rate of soil erosion. (4 points)
49. Briefly describe the characteristics of each soil horizon from the top layer to the bottom layer. (4 points)
50. Briefly describe the roles of heat, pressure, and water in the origin of magma. (4 points)
48. List two human activities and two natural events that can cause a large increase in the rate of soil erosion. (4 points)
49. Briefly describe the characteristics of each soil horizon from the top layer to the bottom layer. (4 points)
50. Briefly describe the roles of heat, pressure, and water in the origin of magma. (4 points)