fluvial systems alluvial fan, meandering river, braided river
DESCRIPTION
Fluvial Systems Alluvial Fan, Meandering River, Braided River. Amy Asanuma Zack St.Clair. Alluvial Fan. Poorly Sorted Sediments with abundant gravel sized detritus Boulders – Sands Cone Shaped with network of branching distributary channels that cross the fan. - PowerPoint PPT PresentationTRANSCRIPT
Fluvial SystemsAlluvial Fan, Meandering
River, Braided River
Amy AsanumaZack St.Clair
Alluvial Fan
• Poorly Sorted Sediments with abundant gravel sized detritus
• Boulders – Sands• Cone Shaped with
network of branching distributary channels that cross the fan
Wrangell-St. Elias National Park, Alaska
Sedimentary Processes
• Debris-flow Deposits• Mud Flows• Landslides• Sheet flood• Incised-channel flow
Sedimentary Structures
• Cross beds• Steep gradient ~5-10 degrees• Building on top of itself• Coarsen Upwards
Braided River
• Poor sorting – better than alluvial fans• Gravels – Sands• Steep Channel Gradient
Resurrection River, Kenai Peninsula, Alaska
Sedimentary Structures
• Trough/Tabular Cross beds• Laminations• Sedimentary Load > Water• Fining Upwards and Repeats• Erodible Banks
Meandering River
• Sediment Load < Water• Gravels – Muds • Moderate Sorting
Owens River, CA
Sedimentary Structures
• Shallow Gradient• Fining Upwards• Ripples• Cross Beds• Bioturbidation
Oblique Dunes in a Meandering River System, Muddy Creek, Wyoming
Fossils
Stratigraphic Section
Fluvial System Example in History
• Alluvial Fan-Important in Precambrian and early Paleozoic time before land plants could provide vegetation cover to inhibit erosion
Present Day Fluvial System
• Alluvial Fan-common in areas of high relief, at the base of a mountain range, abundant supply of sediment needed
Present Day Braided River
• Extensive braided river systems are found in Alaska, Canada, New Zealand's South Island, and the Himalayas, which all contain young, rapidly eroding mountains
Works Cited
• Boggs Jr, Sam. Princiles of Sedimentology and Stratigraphy. Fifth Edition. New Jersey: Pearson Prentice Hall, 2011. 211-220. Print.