Plz hurry 70 points

Why are people often surprised when a volcano erupts?

Explain how the density of ocean water is affected by temperature and how this results in major ocean currents distributing heat away from the equator toward the poles?

These factors threaten north americas ecosystems

17. the soil erosion pictured here is the result of what? a. harvesting renewable resources at a rate greater than the sustainable yield b. a mudslide caused by excessive rains c. harvesting renewable resources at a rate lower than the sustainable yield d. the transition between geologic eras and eons