What will happen if:
the top layer of soil is exposed.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Top Layer of Soil**: The top layer of soil, often referred to as the "topsoil," is the most fertile part of the soil. It contains a high concentration of nutrients and organic matter, which are essential for plant growth.

2. **Impact of Exposure or Removal**: When the top layer of soil is exposed or removed, it leads to a process known as soil erosion. This can occur due to various factors such as water runoff, wind, or human activities like deforestation and agriculture.

3. **Consequences of Soil Erosion**: Once the topsoil is removed, the underlying layers of soil are exposed. These lower layers are typically harder and less fertile compared to the topsoil. They contain less organic matter (humus), which is crucial for retaining moisture and nutrients.

...