1. Erosion of rock by moving water
The Stream Table
Erosion of rock by moving water

2. The Stream Table
In a straight section of a stream, the fastest water is in the middle above center

3. Relationship of Transported Particle Size to Water Velocity (p
Relationship of Transported Particle Size to Water Velocity (p.6 of reference table)

4. Two Events: Erosion and Deposition
On a curve, the fastest water gets thrown to the outside and that's where erosion will happen. The slowest water hugs the inside of the stream and that is where deposition takes place

5. What affects Stream Velocity
Water flows downhill, pulled by the force of gravity.
Friction between the moving water and the banks of a stream (and even air) slows the current.
The speed of any stream is determined by a balance between the forces of gravity and friction.

6. What happens along the stream?
Bends in a stream are called meanders.
At a meander inertia swings the fastest flowing water to the outside of the bend.
Inertia is the property of matter that resists changes in motion.
This difference in the waters speed causes erosion on the outside of the stream bed and deposition along the inside.

7. The Meandering Stream

8. Deposition
Deposition occurs as the water enters the mouth of the lake (delta).
Sediments settle out of the water. The sediments are layered and sorted.

9. Horizontal Sorting
As water velocity begins to decrease, larger sediments begin to settle out followed by the smaller sediments.

10. Formation of Crossbeds and Graded Bedding
Crossbeds are formed when several horizontal sorting events happen on top of each other such as in a river delta as the stream meanders back and forth.
Graded bedding occurs when flooding occurs.

11. Vertical Sorting
Vertical Sorting- caused by larger, rounder, denser sediments settling first.

12. Evidence in Rock of Erosion by Water
A V-shaped valley is evidence of water erosion.

13. Age of Streams Affects the Rate of Erosion
The meander widens from erosion on the outside and deposition on the inside. The two sides of the meander erode into each other. Water slows in the outside loop causing deposition . The loop gets cut off into an “Oxbow Lake” while the stream returns to a straighter course

14. A Youthful Stream Narrow V-shaped Downcutting Swift water
Steep gradient
Erosion is dominant

15. Mature Stream Lateral Erosion begins Meanders develop
Floodplains develop
Gradient lowers

16. Old Age Wide meanders and oxbow lakes Wide floodplain Low velocity
Low gradient
Dynamic equilibrium between erosion and deposition