OSAT World History/Geography Practice Test

The motion of glaciers is primarily caused by gravity. Glaciers are massive bodies of ice that accumulate over time, usually in mountainous or polar regions. As they gain thickness and the weight of the ice increases, gravity exerts a significant force that causes the glacier to move. This movement occurs in two main ways: the entire glacier can flow downward as a unit, and within the glacier, the ice can also experience internal deformation where it flows and deforms under its own weight.

While erosion, wind, and temperature change can influence the characteristics of glaciers and their surroundings, they do not directly cause the glaciers themselves to move. Erosion describes the process by which glaciers carve out valleys and shape the landscape as they advance, but it is a result of glacial movement rather than the cause. Wind can affect surface conditions or transport sediments, but it is not a driving force behind glacial motion. Temperature changes may impact the melting and freezing processes of glaciers, which can influence their stability and volume, but the fundamental movement is due to the gravitational force acting on the mass of ice.