Science Olympiad Dynamic Planet Practice Test

What causes the effects of post-glacial rebound on sea level?

1. The movement of tectonic plates

2. Crustal motion from weight removal of ice sheets

3. The rise of mantle plumes

4. Active volcanic activity

The correct answer is: Crustal motion from weight removal of ice sheets

Post-glacial rebound is primarily driven by crustal motion resulting from the removal of the immense weight of ice sheets that accumulated during glacial periods. When these ice sheets begin to melt, the pressure on the Earth's crust is relieved, allowing it to gradually rise. This vertical movement of the crust can significantly affect local and regional sea levels. As the crust rebounds, areas that were once below sea level may begin to rise above it, while the surrounding sea level may also change, primarily due to the redistribution of water. The process can take thousands of years and results in a dynamic adjustment of land and sea interactions. This rebound can contribute to local sea-level rise or fall, depending on the balance of forces at play in that particular region. In contrast, the other options involve geological processes but do not directly relate to the specific mechanism of post-glacial rebound affecting sea levels. The movement of tectonic plates and the rise of mantle plumes are broader geological phenomena not specifically tied to the immediate response of the crust after an ice sheet melts. Similarly, active volcanic activity can impact local geography and potentially affect sea levels, but it is not the primary mechanism responsible for the rebound effect seen after glacial ice melts.