Continental Glaciers
Glaciers that cover broad, continent-sized areas are called continental glaciers. These glaciers form in cold climates where snow accumulates over many years. A continental glacier is thickest at its center. The weight of the center forces the rest of the glacier to flatten in all directions. In the past, when Earth experienced colder average temperatures than it does today, continental glaciers covered huge portions of Earth's surface. Today, they are confined to Greenland and Antarctica.
Continental glaciers move outward when snow gathers at the zone of accumulation, a location in which more snow falls than melts, evaporates, or sublimates. The zone of accumulation is the center of the ice sheet. Continental glacier recede when the ends melt faster than the zone of accumulation builds up snow and ice.
Continental glaciers move outward when snow gathers at the zone of accumulation, a location in which more snow falls than melts, evaporates, or sublimates. The zone of accumulation is the center of the ice sheet. Continental glacier recede when the ends melt faster than the zone of accumulation builds up snow and ice.
Valley Glaciers
Valley glaciers are glaciers that form in valleys in high, mountainous areas. The movement of a valley glacier occurs when the growing ice mass becomes so heavy that the ice maintains its rigid shape and begins to flow. For most valley glaciers,flow begins when the accumulation of snow and ice exceeds 20 m in thickness.As a valley glacier moves, deep cracks in the surface of the ice, called crevasses, can form.
The speed of a valley glacier's movements is affected by the slope of the valley floor, the temperature and thickness of the ice, and the shape of the valley walls. The sides and bottom of a valley glacier move more slowly than the middle because friction slows down the sides and bottom where the glacier comes in contact with the ground. Movement downslope is usually slow-less than a few millimeters per day. Over time, as valley glaciers flow downslope, their powerful carving action transaction V-shaped stream valley into U-shaped glacial valleys.
Valley glaciers move outward when snow gathers at the zone of accumulation, a location in which more snow falls than melts, evaporates, or sublimates. For valley glaciers, the zone of accumulation is at the top of mountains. This type of glacier also recedeswhen the ends melt faster than the zone of accumulation builds up snow and ice.
The speed of a valley glacier's movements is affected by the slope of the valley floor, the temperature and thickness of the ice, and the shape of the valley walls. The sides and bottom of a valley glacier move more slowly than the middle because friction slows down the sides and bottom where the glacier comes in contact with the ground. Movement downslope is usually slow-less than a few millimeters per day. Over time, as valley glaciers flow downslope, their powerful carving action transaction V-shaped stream valley into U-shaped glacial valleys.
Valley glaciers move outward when snow gathers at the zone of accumulation, a location in which more snow falls than melts, evaporates, or sublimates. For valley glaciers, the zone of accumulation is at the top of mountains. This type of glacier also recedeswhen the ends melt faster than the zone of accumulation builds up snow and ice.