libterm.com Outwash plains form from sediment deposited by meltwater flowing from glaciers, creating extensive, flat areas composed mainly of sand and gravel. These plains play a crucial role in shaping landscapes and influencing groundwater flow due to their high permeability. Explore the article to understand how outwash plains impact your environment and why they are important in geology.
Table of Comparison
| Feature | Outwash Plain | Kame |
|---|---|---|
| Definition | Flat, expansive landform formed by glacial meltwater depositing sorted sediments | Irregular, mound-shaped hill made of glacial sediment deposited in depressions on a melting glacier |
| Formation | Deposited by braided streams of meltwater beyond glacier terminus | Accumulated in ice crevices or holes, left as glacier melts |
| Shape | Broad, flat, gently sloping | Steep-sided, conical or mounded |
| Material | Sorted sand and gravel | Unsorted till, sand, and gravel |
| Size | Large, extensive landforms covering wide areas | Small to medium-sized hills |
| Location | Downstream of glaciers, often in front of ice sheets | On glacial terrain, often scattered on moraines or valleys |
| Examples | Sandur plains in Iceland, North American outwash plains | Kames in New England, Canada |
Introduction to Outwash Plains and Kames
Outwash plains form extensive, flat landscapes composed primarily of sand and gravel deposited by meltwater flowing from glaciers, characterized by well-sorted sediments due to water sorting materials by size and weight. Kames are irregularly shaped hills or mounds made up of sand, gravel, and till that accumulate in depressions on retreating glaciers before being deposited on the ground surface. Both features are crucial in glacial geomorphology, with outwash plains spreading sediments across broad areas while kames represent localized sediment deposits reflecting complex ice melt dynamics.
Formation Processes of Outwash Plains
Outwash plains form from the deposition of sediments carried by meltwater from retreating glaciers, creating broad, flat areas composed primarily of sand and gravel sorted by flowing water. These plains develop as glacier meltwater streams deposit sorted sediments beyond the ice margin, unlike kames which are mounds or hills formed by sediment accumulation in crevices or depressions on the glacier surface. The stratified and well-sorted sediments of outwash plains contrast with the often poorly sorted sediments found in kames, reflecting differences in their glacial deposition processes.
How Kames Develop in Glacial Landscapes
Kames form in glacial landscapes through the deposition of sediment in depressions or openings on melting glacier surfaces, often creating mounds or hills composed of sand, gravel, and till. These sedimentary features result from meltwater streams carrying and sorting debris, which accumulates in kettles or crevasses as the glacier retreats. Outwash plains, in contrast, develop from broad, flat areas where meltwater distributes sorted sands and gravels away from the glacier terminus, creating extensive sediment deposits distinct from the localized and irregular shapes of kames.
Key Geological Characteristics: Outwash Plains vs Kames
Outwash plains are extensive, flat areas formed by sediment deposits from braided glacial meltwater streams, characterized by well-sorted sand and gravel layers that indicate high-energy water flow. Kames are irregularly shaped hills or mounds composed of stratified sand and gravel deposited by melting ice in depressions or openings on glacier surfaces, reflecting localized sediment accumulation. Unlike the broad, gently sloping outwash plains, kames are steeper and more variable in size, representing sediment dropped as meltwater stagnates within ice crevasses or cavities.
Sediment Composition and Sorting Differences
Outwash plains consist primarily of well-sorted sand and gravel deposited by meltwater streams, reflecting high-energy water transport that removes finer particles. Kames are composed of poorly sorted sediments including sand, gravel, silt, and clay, deposited directly by stagnant meltwater and ice without significant reworking. The sediment composition in outwash plains shows distinct stratification, while kames exhibit a more heterogeneous and chaotic sediment structure.
Surface Features and Landform Structures
Outwash plains exhibit broad, flat surfaces composed of well-sorted sand and gravel deposited by meltwater streams, characterized by braided channels and stratified sediments. Kames are irregularly shaped mounds or hills formed from sediment accumulation in depressions on retreating glaciers, featuring steep sides and unsorted materials. The distinct landform structures of outwash plains and kames reflect their formation processes--outwash plains result from extensive sediment dispersal by glacial meltwater, while kames represent localized sediment deposits from stagnant ice.
Hydrological Dynamics in Outwash Plains and Kames
Outwash plains exhibit high permeability due to well-sorted sands and gravels deposited by glacial meltwater, allowing rapid infiltration and groundwater recharge. Kames, composed of irregular kame mounds and hills, feature more heterogeneous sediments that create localized variable water retention and flow pathways. The hydrological dynamics in outwash plains promote extensive subsurface flow, while kames influence surface runoff patterns and create isolated seepage zones.
Ecological Impact of Outwash Plains and Kames
Outwash plains, formed by meltwater deposits, create extensive flat terrains that support diverse wetland ecosystems and nutrient-rich soils crucial for plant communities. Kames, composed of sorted sand and gravel mounds deposited by glacial meltwater, provide unique microhabitats that support specialized flora and fauna due to their elevated and well-drained conditions. Both landforms influence local biodiversity, with outwash plains fostering broad ecological networks, while kames contribute to habitat heterogeneity and species diversity in glacial landscapes.
Real-World Examples: Outwash Plains vs Kames
The Sandur Plain in Iceland exemplifies a classic outwash plain formed by glacial meltwater spreading sediments over a broad area, contrasted by the kame terraces and mounds found in the Finger Lakes region of New York, where localized sediment deposition created distinct kame formations. Outwash plains like the Misquah Hills area in Minnesota demonstrate extensive, stratified sand and gravel deposits from meltwater streams, while the kames near Loch Lomond in Scotland highlight irregular, steep-sided hills formed by sediment accumulation in glacial depressions. These real-world examples illustrate the difference between the broad, flat sediment dispersal of outwash plains and the irregular, localized sedimentary mounds of kames.
Summary: Contrasting Outwash Plains and Kames
Outwash plains are extensive, flat areas formed by meltwater streams depositing sorted sediments in front of glaciers, creating well-layered sands and gravels. Kames, in contrast, are irregularly shaped hills composed of stratified sand and gravel deposited by meltwater in depressions or crevices on the glacier surface. These landforms differ in shape, sediment sorting, and depositional processes, with outwash plains providing broad, level landscapes and kames producing isolated, uneven mounds.
Outwash plain Infographic
