OUTWASH PLAIN Meaning and
Definition
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An outwash plain is a geological landform that is primarily formed by the erosion and deposition of glacial meltwater. It is a flat and relatively featureless area that stretches out beyond the terminal moraine, which is the accumulation of soil and rocks deposited at the end of a glacier.
During periods of glaciation, as the glacier advances, it carries with it a significant amount of debris. As the glacier starts to melt, meltwater streams are formed, flowing away from the glacier. These meltwater streams carry and transport the debris, depositing it in a sorted manner on the outwash plain.
Outwash plains are characterized by their gentle slopes, which are primarily composed of well-sorted and layered sediments, including sand, silt, and gravel. Due to the sorting process, the sediments within the outwash plain often exhibit distinct layers based on their size and density. These layers can be used by geologists to infer the history and characteristics of the glacier that deposited them.
Outwash plains are typically found in front of retreating or melted glaciers, and they can extend for several miles or even hundreds of miles, covering vast areas of land. They are important features in glacial landscapes as they serve as drainage systems, allowing the efficient channeling of meltwater away from the ice sheet. Furthermore, outwash plains are often fertile due to the presence of sedimentary deposits, making them suitable for agriculture and human settlement.
Etymology of OUTWASH PLAIN
The term "outwash plain" is composed of two words: "outwash" and "plain".
The word "outwash" first appeared in the mid-19th century and is derived from the combination of "out" and "wash". In this context, "wash" refers to the action of water flowing and carrying sediments away. The prefix "out" indicates the movement of these sediments from their original location towards an outer area.
"Plain" has a separate etymology and came into English from the Old French word "plain", which means flat or level. It dates back to the 12th century and ultimately finds its roots in the Latin "planus" meaning flat or level ground.
Therefore, an "outwash plain" refers to a flat or level area of land formed by the deposition of sediments carried by water flowing from a glacier or ice sheet, typically located beyond the glacial margin.
