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Glacial Processes. Glaciers are large masses of ice that move over time. On the basis of size and shape, glaciers can be divided into two types: Valley glaciers – Glaciers that flow down well defined stream valleys in mountainous regions.
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Glacial Processes • Glaciers are large masses of ice that move over time
On the basis of size and shape, glaciers can be divided into two types: • Valley glaciers – Glaciers that flow down well defined stream valleys in mountainous regions
Continental glaciers – Large ice sheets that cover most of a continent and flow independent of topography
There are two main zones of a glacier: • Zone of Accumulation – Here snow and ice accumulate and flow toward the: • Zone of Ablation – Snow and ice are lost through melting, sublimation, and calving
If accumulation > ablation, glacier advances • If accumulation < ablation, glacier retreats • If accumulation = ablation, glacier remains a constant size
As glaciers move they erode and transport sediment and rock. This creates several different types of erosional and depositional features and distinct water bodies. Common features include: - Cirques - Lateral Moraines - Glacial Striations - Terminal Moraines - Erratics and Till - Lateral Moraines - Drumlins - Kettles
Glacial Till Glacial Striations Drumlin
Lateral Moraine (dark brown running from center to lower left) Formation of a kettle
Glacier development is influenced by climate changes, which can be attributed to three astronomical cycles
During warmer periods, glaciers retreat (melt), causing sea-level to rise • During cooler periods, glaciers advance, causing sea-level to fall • If all of the ice on Earth melted (25 million km3) sea-level would rise 65 meters