Soru

In mid-nineteenth-century glaciology, Louis Agassiz proposed that extensive ice sheets had once covered northern Europe, attributing the transport of massive erratic boulders to glacial drift rather than catastrophic floods. While earlier naturalists like Leopold von Buch argued that these erratics were dispersed by high-velocity currents of liquid water carrying debris, Agassiz cited the presence of polished bedrock surfaces and fine striations beneath the boulders as direct evidence of ice abrasion. Agassiz asserted that liquid water alone lacked the frictional mass required to scratch dense granite, whereas slow-moving glaciers bearing embedded rock fragments naturally carved these distinct linear grooves into the underlying strata.

According to the passage, Agassiz cited which of the following as evidence that erratic boulders were transported by glaciers rather than liquid water?