Question

how do erosion and deposition work together to form sand dunes?
waves cause erosion along coastlines and deposit sand away from the shore.
erosion occurs as surface water carries sediment and the sediment is deposited near oceans and lakes.
glaciers cause erosion through the movement of large chunks of ice, which are deposited and form depressions.
erosion occurs through deflation, and sand that was picked up is deposited against an obstruction.

Explanation:

To determine the correct answer, we analyze each option:

• Option 1: Waves eroding coastlines and depositing sand away from shore is related to coastal landforms, not sand dunes (which are formed by wind).
• Option 2: Surface water carrying sediment and depositing near oceans/lakes is about fluvial deposition, not sand dune formation.
• Option 3: Glaciers eroding and depositing ice chunks to form depressions is glacial erosion/deposition, unrelated to sand dunes.
• Option 4: Sand dunes are formed by wind. Deflation (wind erosion) picks up sand, and when the wind slows, the sand is deposited against an obstruction (like rocks, plants), which is the process of sand dune formation.

Answer:

D. Erosion occurs through deflation, and sand that was picked up is deposited against an obstruction.