Glacio-Fluvial Deposition Flashcards
What is Glacio-Fluvial Deposition?
Deposition of material carried by meltwater either underneath a glacier or at the end of a glacier. These deposits are very different to Till (ice deposits) and are referred to as Outwash
What are the characteristics of glacial-fluvial Material?
· Smoother and more rounded due to contact with water & attrition.
· Smaller than till due to erosion, and because meltwater streams have less energy than glaciers, so only carry finer material.
· Sorted horizontally – largest material is dropped nearest the snout, and progressively finer material further down the valley.
· Stratified vertically into seasonal and annual bands of deposition
What are outwash Plains?
Also called Sandurs. A large expanse of meltwater deposits over a wide, flat area. The most inland parts of the plain will have the largest sized material, but nearer the sea the particles become smaller. These are un-vegetated as the sediment is fine & loose and constantly blown around by wind
What are Eskers and how are they formed?
Long snaking ridges on the valley floor. Material is deposited in sub-glacial tunnels. Over time, these tunnels can get completely blocked with sediment creating long tubes of sediment under the glacier. When the ice eventually melts away it leaves behind these tubes as long snake-like ridges going down the middle of a valley.
What are Kames?
Hills/hummocks of sand and gravel that form at the base of a moulin (water shoot through a glacier). Formed by water carrying debris from the top of the glacier and depositing it as a mound underneath the glacier.
What are Kame Terraces?
Kame terraces are found along the side of a glacial valley where meltwater runs between the glacier and the valley side. Formed when material is deposited when there is a loss of energy which get’s sorted because larger material is dropped first and then smaller material dropped last
How do you identify if the landform is an Esker or Medial Moraine?
Eskers look the same as Medial Moraines, but to identify them as eskers we have to see if the sediment is sorted & smooth.
