How are Continental Glaciers different from valley Glaciers?
Continental glaciers, also known as ice sheets, are vast ice masses that spread over relatively flat terrain and cover large portions of continents, like Greenland and Antarctica. Valley glaciers, on the other hand, are smaller glaciers that form within mountain valleys or between peaks.
To understand more about how these glaciers are different, let's break down the process of their formation:
1. Formation:
- Continental Glaciers: They form when snow continually accumulates in a region where the rate of snowfall exceeds the rate of snowmelt. Over time, the accumulated snow compresses into ice, forming an ice sheet that covers a wide area.
- Valley Glaciers: They develop within mountainous regions where snow accumulates in the valleys. Over time, the snow compacts into ice and starts to move downhill under the influence of gravity.
2. Size and Shape:
- Continental Glaciers: They are vast in size, typically covering more than 50,000 square kilometers. They are characterized by their relatively flat morphology, spreading out over large areas.
- Valley Glaciers: They are significantly smaller than continental glaciers, usually ranging from a few kilometers to tens of kilometers in length. They tend to have a long, narrow shape, following the contours of the valleys they occupy.
3. Flow Dynamics:
- Continental Glaciers: Due to their immense size, they spread outward in all directions under their own weight, often transforming the landscape beneath them. They flow very slowly, typically a few centimeters per day.
- Valley Glaciers: They flow downstream along the path of least resistance, following the alignment of the valley they occupy. Unlike continental glaciers, valley glaciers can flow faster, reaching speeds of several meters per day.
4. Erosion and Deposition:
- Continental Glaciers: As continental glaciers move, they erode the underlying rock and sediment, creating U-shaped valleys and leaving behind distinctive landforms like moraines and drumlins. They also deposit significant amounts of sediment as they melt.
- Valley Glaciers: They also erode the underlying terrain, but tend to create V-shaped valleys. They deposit glacial till and other debris as lateral and terminal moraines, which can be used to identify their past extent.
In summary, continental glaciers are larger, cover vast areas, flow slowly, and reshape the landscape, while valley glaciers are smaller, occupy mountain valleys, flow faster, and have a different impact on the landscape.