Glaciers always melt at the _____ first.

Options

A. top surface
B. sides
C. bottom
D. middle surface

Answer

**Step-by-Step Solution:**

1. **Understanding the Structure of a Glacier:**
- Glaciers are large masses of ice that form from compacted snow over many years. They have different layers, including the top surface, middle surface, bottom, and sides.

2. **Identifying the Melting Process:**
- When glaciers melt, the process is influenced by various factors, including temperature and pressure.

3. **Analyzing the Options:**
- The options provided are:
- Top surface
- Sides
- Bottom
- Middle surface

4. **Evaluating Each Option:**
- **Top Surface:** The top surface experiences lower pressure compared to the bottom. While it may receive sunlight, the pressure is not sufficient to initiate melting.
- **Sides:** The sides of the glacier also experience lower pressure and are not the primary melting point.
- **Middle Surface:** The middle surface has moderate pressure, but it is still less than the pressure at the bottom.
- **Bottom:** The bottom of the glacier experiences the highest pressure due to the weight of the ice above. Additionally, the temperature at the bottom is relatively warmer compared to the other parts of the glacier.

5. **Conclusion:**
- Based on the analysis, glaciers always melt at the **bottom** first due to the combination of high pressure and relatively higher temperature.

**Final Answer:**
Glaciers always melt at the **bottom** first.

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