B. Plucking. Glaciers are known to migrate and move at certain speeds, and the water that is in front of a moving glacier is known as subglacial water. This water has the ability to penetrate cracks and fractures in the bedrock, followed by the water freezing and then expanding. This expansion forces rock up and become part of the glacier.
Over time, the wind erodes the sandstone into different shapes and sizes. It does this by blowing the sand around and off the stones.
In the same way as the sand dunes, the rock underwater was smoothed by the passing of the water. The rock she found underground, however, has rough edges because of the rocks breaking off and the cooling of lava.
