What phenomenon provides ice evidence in bedrock for supporting continental drift theories?

Glacial activity is the phenomenon that provides critical evidence of ice in bedrock, which supports the theories of continental drift. During glacial periods, vast ice sheets cover large areas of the Earth's surface. As glaciers move and retreat, they carve out the landscape, leaving behind distinctive geological features such as striations and drumlins. These features can often be found in locations that are now far from polar regions, indicating that they once experienced conditions suitable for glaciation.

The identification of glacial deposits on continents that are now separated by oceans suggests that these landmasses were once joined, allowing glaciers to spread across what is now distant terrain. This aligns with the concept of continental drift, which posits that continents have shifted positions over geological time. The presence of similar glacial marks on continents that are currently located at different latitudes provides tangible evidence that supports the movement of these landmasses.

Other phenomena such as volcanic eruptions, earthquakes, and tsunamis do not provide the same direct evidence of historical ice coverage across continents. While they are significant geological events, they do not leave behind the specific markers related to glacial activity that furnish robust proof of past climatic conditions and the former positions of continents.