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River Systems Four types, braided, meandering, anastamosing and straight.

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Presentation on theme: "River Systems Four types, braided, meandering, anastamosing and straight."— Presentation transcript:

1 River Systems Four types, braided, meandering, anastamosing and straight

2 Grand Canyon, erosion

3 River incision in Indus Suture Zone

4 River types

5 Links between sinuosity and slope

6 Anastomosing river stratigraphy

7 Braided rivers Typically developed in mountainous terrain on higher gradients. Typified by high degree of seasonality. Permanent channels with ripple crossed bedded sands develop during periods of low flow. These channels meander between sand bars that are active only during flood stage, these develop larger scale cross beds. Sediments are typically sandy and pebbly, usually moderate to well sorted, texturally moderately mature. Ancient example- Devonian Old Red Sandstone. Modern example - Saskatchewan River.

8 Braided River Model

9 Braided River Model and stratigraphy

10 Braided River

11 Braided geometry, Matanuksa River, Alaska

12 Braided River, Nubra, India

13 Braided River, Shyok River, India

14 Anastomosing River, Indian foreland

15 Channel sandstone facies

16 Meandering Rivers Typically developed in coastal plain areas, lower gradient. More continuous flow, finer grained sediment than braided. Channel sediment is marked by the deep stream migration of meanders and the construction of cross laminated sands on point bars in the inner bends of meanders. Channels are separated by levees from flood plains that are comprised of finer grained muds and sands deposited after breach of levee during flood stage, usually vegetated. Flood stage can lead to cut-off of meanders and break- through of river.

17 Meandering Rivers, contd. Abandoned meanders become Ox-bow lakes, filled by clays. Meandering river deposits typified by fining- upward stratigraphy. Sediments are typically sandy, silty and clayey. Well sorted. Sandstones form isolated channels in finer background. Ancient example- Jurassic, Brent Group of North Sea. Modern example - Brazos and Mississippi Rivers.

18 Meanders in the Amazon Basin

19 McKenzie River meanders and glacial lakes

20 Ox Bow Lake/meanders

21 Point bar deposits

22 Braided versus meandering river type sections

23 Impact of sinuosity on stratigraphy

24 Channel migration-Ganges

25 Ganges and Himalaya thrust front

26 Indus River and tectonic uplift, Kohat Plateau

27 Effect of tectonism on location of rivers

28 Fluvial facies examples

29 Indus Molasse, fluvial sandstone

30 Slumped sediment, modern Indus River

31 Climbing wave ripples, Indus River


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