During the late nineteenth and early twentieth centuries, direct observations showed that a glacier in Switzerland flowed forward in the downhill direction while its snout (terminus)was retreating higher up the valley. Which of the following explains these observations in a rational, scientific way?
A)The melting rate of ice in the glacier exceeded the rate at which new snow and ice were added to the glacier.
B)Cooler temperatures meant slower forward glacier flow resulting in snout retreat.
C)Rocky debris in the valley downhill from the snout was deposited by Noah's flood.
D)The glacial hypothesis was finally accepted as a scientific theory.

Question

Quizplus · Accepted Answer

The observation of the glacier movement is consistent with the concept of mass balance, which refers to the difference between the accumulation (addition) of snow and ice to a glacier and the ablation (loss) of ice due to melting and sublimation. If more ice is melting than is being added to the glacier, it will have a negative mass balance, and the terminus will retreat while the glacier continues to flow downhill.

During the Late Nineteenth and Early Twentieth Centuries, Direct Observations