Upload
johnda
View
139
Download
2
Tags:
Embed Size (px)
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 Presentation
Citation preview
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.