Rivers and Streams

1. Rivers and Streams

2. Water cycle: the continuous movement of water between the atmosphere, the land and the oceans

3. Steps of the water cycle: • 1) radiation • 2) evaporation • 3) condensation • 4) precipitation • 5)Transpiration ( loss of water by plants) • 6) run off • 7) ground water

4. Vocab • Abrasion: grinding action • Stream discharge: total volume of water flowing past a given pt in a certain amount of time

5. Flood plain: part of a valley floor covered by water during a flood. Very fertile • Gully: a small V-shaped valley

6. Divide: high land separating one gully from another • Rocky Mountains serve as an example of a continental divide

7. Tributary: a small river or creek leading into a larger stream • River system: all of the tributaries leading into a river • Mississippi River System largest in the U.S.

8. Watershed: All of the land that drains into a river • Augusta county is part of the Chesapeake Bay Watershed • Rejuvenation: process of an older stream getting “new life” and becoming as a young stream

9. Watersheds • Water shed: all of the area that drains into a larger body of water • Chesapeake Bay--- largest watershed in eastern U.S. • Estuary---a mixture of salt and fresh water

10. Major water sheds of Va • 1. Big Sandy • 2. James • 3. New • 4. Chowan • 5. Potomac-shennandoah • 6. Tennessee • 7. York • 8. Roanoke • 9. Rappahennock

11. Watersheds • Water sheds of Va: • Ohio/Tennessee---to Gulf of Mexico • Tennessee • New • Roanoke • Chowan • Big Sandy

12. Watersheds • Chesapeake to Atlantic • James • York • Potomac-Shenandoah • Rappahannock

13. Types of Stream Patterns • Stream pattern—determined by composition of bedrock beneath • A) Dendritic- most common like branches on a tree Mississippi River

14. Stream Patterns • B) Rectangular--- fractured bedrock streams makes right angles in the rock

15. Stream Patterns • C) Radial • A number of streams originate from a single point • Mountain peaks will have a lake at the top and several streams flowing from it

16. Carrying Power of Stream • Rivers carry sediment in 3 ways: • 25% in solution---dissolved minerals • 25% as bed load—sand and pebbles on the bottom • 50% suspension—muddy with clay,silt and sand. Turbulence keeps it stirred and muddy

17. Stream Age • Young Streams • V-shape • High erosion • High speed • Steep valley---canyons, gorges and chasms

18. Stream Age • Old Streams: U-shaped valleys Slow speed Low discharge Low erosion Meanders form---large broad curves

19. Features of a Stream • 1)Meander: a curve in the stream • An old stream will have many curves and a wide valley • A meandering stream will have FAST water on the outside of curve and SLOW water on the inside of a meander • Draw on board

20. Features of a Stream • 2) Channel---narrow pathway of water flow in stream • 3) oxbow lake---as the stream slows down it deposits sediment, it will eventually cut the meander off from the stream. • Oxbow lakes form when stream is near the base ---water is very slow moving • NO OXBOW LAKES IN THE MOUNTAINS

21. Features of Streams • 4) plunge pools: large depression at the base of a waterfall. The water is so forceful it erodes the rock below in a process called UNDERMINING

22. Features of streams • 5) Delta: flat, fan shaped deposits at the MOUTH of a RIVER • water slows down down and the silt falls out making the area very fertile • Draw on board

23. Features of Stream • 6) Alluvial fan: fan-shaped deposit at the base of a mountain that has been washed down • Compare and contrast alluvial fan and delta.

24. Delta Formation Sequence: • Young • Middle age • Old • Draw on board

25. Page 388 and 389 • # 1-9,11, 13,14,15 and 32-39