Passage Summary: There's a volcanic rock sitting on sedimentary ground where glaciers once moved, so a glacier probably carried it there from far away.

Conclusion: A glacier likely transported the volcanic boulder from a distant location to its current sedimentary environment.

Reasoning: The boulder's material doesn't match the local rock, and the area experienced glacial movement in the past.

Analysis: To weaken this, we need to find another way that a volcanic rock could end up in a sedimentary area. Perhaps there was a local volcanic pipe that didn't affect the surrounding surface rock, or maybe the southward-moving glaciers actually came from a place that also didn't have volcanic rock. Look for an answer that suggests the boulder actually is local, despite appearances.