What two positive and negative effects human activities have on erosion?

What major factors play a role in global warming? 1. human activity and normal climate conditions 2. natural factors and human activity 3. normal climate conditions and abnormal human activities 4. abnormal human activities and natural factors

According ti the following map, what are the most common mineral resources found in the united states?

If scientists only detect p waves in a certain layer of earths interior what does that tell us?