Abrasion is the process responsible for the formation of rock pillars with mushroom-like shapes.

Explanation:
- Abrasion is a mechanical weathering process that involves the wearing away of rocks and other materials through the frictional action of particles or objects in motion.
- When rocks are subjected to abrasion, they are eroded and gradually shaped into various forms, including rock pillars with mushroom-like shapes.
- The process of abrasion typically occurs in environments where wind, water, or ice carry abrasive particles that come into contact with the rock surfaces.
- Wind Abrasion: In desert environments, strong winds often carry sand particles that can act as abrasives. As these particles collide with rocks, they cause erosion and gradually shape them into mushroom-like pillars.
- Water Abrasion: In coastal areas or river valleys, water currents transport sediment particles that can also act as abrasives. When these particles collide with rocks, they cause erosion and contribute to the formation of mushroom-shaped pillars.
- Ice Abrasion: In glaciated regions, glaciers or ice sheets can carry rocks and sediments that act as abrasives. As the ice moves, it can grind against the bedrock and shape it into distinctive formations, including mushroom-like pillars.
- Over time, repeated abrasion by wind, water, or ice can sculpt rocks into various shapes. In the case of mushroom-like pillars, the erosion is typically concentrated at the base of the rock, leading to a narrower stem and a wider top, resembling the shape of a mushroom.

Conclusion:
- Abrasion is the process responsible for the formation of rock pillars with mushroom-like shapes.
- This process occurs through the mechanical action of wind, water, or ice carrying abrasive particles that gradually erode and shape the rocks into distinct formations.
- Understanding the processes of erosion and weathering is important in studying the geological formation of various landforms.