1. Erosion: This is the process by which soil and rock are worn away by the action of water, wind, or ice. Erosion can occur naturally, or it can be accelerated by human activities such as mining and deforestation.

2. Glaciation: This is the process by which ice sheets and glaciers move across the Earth's surface, scraping away soil and rock. Glaciation can also occur naturally, or it can be accelerated by human activities such as climate change.