1. Stream Evolution Young Mature Old Age

2. Weathering and Erosion by water Running water on the Earth’s surface is responsible for much of the shaping of the landscape that we see. Understanding how these dynamic systems evolve with time is important in understanding the earth system.

3. Rivers and Humans Rivers have been one of the sources of food, water and transport since pre-historic times. The rivers aid the cultivation of crops by supplying water. Historians claim navigation of rivers dates back to the Indus Valley Civilization (2600–1900 BCE) Rivers of the world are the major source of fresh water and they sustain their own food chain

5. The Iguazú Falls, located on the border between Argentina and Brazil, is composed of 275 waterfalls that are strung out along the rim of a crescent-shaped cliff about 2.5 miles long

6. Butcher’s Creek, Australia

7. Black Canyon of the Gunnison River, Colorado

8. Young Steep slope Fast velocity More erosion than deposition Narrow stream channel Canyons, gorges, down-cutting, waterfalls and plunge pools Reichenback River Alps, Switzerland Black river Canyon, Colorado

9. Grand Canyon of the Yellowstone The Grand Canyon of the Yellowstone and Yellowstone Falls in Yellowstone National Park, is a great example of landforms cut by a youthful stream. The canyon is V-shaped, from channel down- cutting and has no flood plain. The channel also has a number of cascading waterfalls typical of youthful streams cut by running water. Photo courtesy of the United States Geological Survey.

10. Grand Canyon of the Yellowstone

11. Youth V-Shaped Valley Rapids Waterfalls No Flood Plain Drainage Divides Broad and Flat, Undissected by Erosion Valley Being Deepened

12. Youthful Landscape, Arizona

13. Mature Rivers A mature river is less steep and flows slowly compared to the youthful river. There are many tributaries that feed a mature river. The sediment deposit is also less. Meanders, flood plains and side-cutting to widen the stream channel Examples of mature river include St. Lawrence River, Ohio River, Genesee River and River Thames.

14. Mature: The St. Lawrence River

16. Amazon runs 3,900 miles through Brazil and Peru

17. The Volga River in Russia runs 2,200 miles through Europe

18. Mature V-Shaped Valley Beginnings of Flood Plain Sand and Gravel Bars Sharp Divides Relief Reaches Maximum Valleys stop deepening

19. Young-Mature Landscape, California

20. Old Age Rivers An old river has a low gradient or gradual slope, slower velocity, more deposition than erosion A wide stream channel that forms flood plains Contains levees, oxbow lakes, meanders, a delta and many tributaries Some of the world famous old rivers include the Ganges, Mississippi, Nile, and Euphrates.

21. Meandering Tyger River, Argentina

22. Old Age Land worn to nearly flat surface (peneplain) Resistant rocks remain as erosional remnants (monadnocks) Rivers meander across extremely wide, flat flood plains