List two environmental consequences that are likely to result from filling valleys with mountaintop tailings, and two consequences that might arise downstream of the mining site.

Mining is an activity which the earth is dig to obtain minerals and oil reservoirs.

Explanation:

The two environmental consequences that are responsible for filling the valleys are soil erosion and downstream mining causing the contamination of the neighboring water source. Soil erosion is resultant of the mining activity causing the trees to be uprooting from their site and making soil prone to the affect of physical factors like wind and water.