Presentation on theme: "1) What are the main geomorphological processes shaping landforms in an area undergoing active glaciation? 2) Show how one named landform has been shaped."— Presentation transcript:
1) What are the main geomorphological processes shaping landforms in an area undergoing active glaciation? 2) Show how one named landform has been shaped by many glacial processes.
Weathering Processes… Freeze thaw weathering or frost shattering.
Nunataks – frost shattered peaks above ice level.
Pressure release of rock can cause physical weathering due to unloading. The majority of igneous rocks were created deep under the Earth's surface at much higher pressures and temperatures. As erosion brings these rock formations to the surface, they become subjected to less and less pressure. This unloading of pressure causes the rocks to fracture horizontally with an increasing number of fractures as the rock approaches the Earth's surface.
Pressure release marks – after glacier retreated. Spalling, the vertical development of fractures, occurs because of the bending stresses of unloaded sheets across a three dimensional plane.
Cirque headwalls are continually being eroded and oversteepened. This ultimately results in sometimes massive rockfalls from the walls. Mass Movement Processes Becomes supraglacial load
Mass Movement - Rock Falls – rapid movement - creates scree or talus slopes
Mass movement of soil and regolith affected by alternate freezing and thawing. Characteristic of saturated soils in high latitudes, both within and beyond the permafrost zone. Mass Movement processes – can be slow e.g. solifluction
Abrasion is the process of a glacier scouring the surface it is moving over. Rocks beneath the surface may be ground up or polished. Glaciers may leave long scratches or grooves called striations in the rock. Erosion Processes
As ice passes over bedrock, abrasion can give it a polished look. Alternatively, large particles in the ice can cut long scours in the basement, called striations Abrasion involves erosion of the substrata by material stuck in the glacier base. Think of sandpaper moving over a board. The particles can be quite large and they scrape, or abrade, the underlying ground further.
Plucking - erosion
Transport Processes – Supraglacial – rocks on top of the ice A supraglacial stream
Englacial moraine (within the glacier) exposed as it melts
Subglacial moraine – load and stream – exposed at base of the snout of the glacier
Supraglacial – medial moraine
Lateral and medial moraines
Deposition Landforms glacial
A small push moraine - of unsorted glacial deposits
Fluvioglacial deposits – from meltwater steams are sorted – with larger boulders dropped near the ice and finer material washed further downstream.