USA Outwash Plains Quiz
Sediment deposition beyond ice margins (10 questions).
USA Outwash Plains Quiz: Quick Study Notes
Outwash plains are distinctive glacial landforms, crucial for understanding the legacy of past ice ages across the United States. Formed by sediment-laden meltwater flowing away from continental glaciers, these plains are vast, relatively flat areas characterized by well-sorted deposits of sand and gravel. This quiz tests your knowledge of their formation, characteristics, and geographic distribution.
Key Concepts
Key Takeaways
- Outwash plains are fluvioglacial deposits, meaning they are formed by glacial meltwater.
- They are composed of stratified, well-sorted sand and gravel.
- The topography is generally flat or gently sloping.
- Common features include braided streams and kettle lakes.
- They are distinct from till plains, which are unsorted and directly deposited by ice.
- Major formations in the USA date primarily to the Pleistocene Epoch.
- Crucial for understanding glacial hydrology and sediment transport.
Frequently Asked Questions
What is an outwash plain?
An outwash plain is a relatively flat area composed of sediments (sand, gravel) deposited by meltwater streams flowing away from a glacier. It’s a fluvioglacial landform.
How are outwash plains formed?
They are formed when meltwater from a retreating glacier carries eroded material (till) and deposits it beyond the ice margin. As the water loses energy, it sorts and deposits the sediment in layers, creating a broad, low-relief plain.
What types of sediments are found in outwash plains?
Outwash plains primarily consist of stratified sand and gravel, often with layers of silt. The sediments are well-sorted and rounded due to the action of flowing water, contrasting with the unsorted nature of glacial till.
Where can outwash plains be found in the USA?
In the USA, outwash plains are common in states that were previously covered or affected by continental glaciers, particularly in the Upper Midwest (e.g., Wisconsin, Michigan, Illinois) and parts of the Northeast.
What is the difference between an outwash plain and a till plain?
An outwash plain is formed by water-deposited, sorted sediments, usually flat. A till plain is formed by direct ice deposition, consisting of unsorted, unstratified sediments (till), and can have a more irregular, hummocky topography.
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