Erosion:
* Plucking: As glaciers move, they freeze to bedrock and as they advance, they pull away chunks of rock, a process known as plucking. This creates large, irregular blocks of rock that are often deposited downstream.
* Abrasion: Embedded rocks and sediment within the glacier act like sandpaper, grinding and smoothing the bedrock as the glacier moves. This creates grooves, striations, and polished surfaces on the bedrock.
* Glacial flour: The intense grinding action creates fine rock particles called glacial flour, which is deposited in lakes, rivers, and sediments.
Transportation:
* Moraines: Glaciers transport a vast amount of rock and sediment, which they deposit along their edges and terminus. These deposits are known as moraines and can be very extensive, forming hills, valleys, and even entire landscapes.
* Outwash plains: Meltwater from glaciers carries fine sediment downstream, creating outwash plains, which are often characterized by well-sorted, sandy deposits.
* Till: The unsorted, often clay-rich material deposited directly by the glacier is called till. Till is often found in moraines and can be very fertile for agriculture.
Deposition:
* Cirques: As glaciers erode, they carve out bowl-shaped depressions known as cirques at the head of valleys.
* U-shaped valleys: Glaciers carve out characteristic U-shaped valleys with steep sides and flat floors, in contrast to the V-shaped valleys created by rivers.
* Fjords: When glaciers retreat, they often leave behind deep, narrow inlets known as fjords.
* Drumlins: Glaciers can deposit elongated hills known as drumlins, which are often found in groups.
Landform Creation:
Glaciers are responsible for creating many dramatic and unique landforms:
* Hanging valleys: Smaller valleys carved by tributary glaciers often hang above the main valley carved by the larger glacier, creating dramatic waterfalls.
* Aretes: Sharp, jagged ridges formed between two cirques are called aretes.
* Horns: A peak formed by the intersection of three or more cirques is called a horn.
Impact on Soil:
* Glacial till: The deposition of till creates fertile soils, but they can also be poorly drained and susceptible to erosion.
* Outwash plains: Outwash plains can have well-drained, sandy soils suitable for agriculture.
* Glacial flour: While not directly creating soil, glacial flour can contribute to nutrient-rich conditions in lakes and streams.
In Conclusion:
Glaciers exert a tremendous influence on the land surface, shaping landscapes, creating unique features, and influencing the formation of soils. Their impact is not always immediate, but it is often dramatic and lasting.
