An area where fresh water from rivers mixes with salt water from the ocean is called an...

• watershed
• water quality
• estuary 
• ecosystem

Plowing cropland can...

• cause greater erosion
• prevent erosion

Planting grass can...

• cause greater erosion
• prevent erosion

Building roads and new buildings can...

• cause greater erosion
• prevent erosion

Cutting down forests can...

• cause greater erosion
• prevent erosion

Planting new trees to replace the ones cut down can...

• cause greater erosion
• prevent erosion

An ________ is made up of living community and nonliving factors that affect it.

• watershed
• water quality
• estuary 
• ecosystem

________ is the process in which rocks and soil are dropped.

• weathering
• erosion
• deposition

What is the movement of rocks and soil from one place to another?

• weathering
• erosion
• deposition

A dead animal is...

• abiotic factor
• biotic factor