Stream Erosion Running Water Energy The water cycle

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Stream Erosion § Running Water § Energy § The water cycle § Most effective

Stream Erosion § Running Water § Energy § The water cycle § Most effective agent in wearing down the surface of the earth § From the sun… Powers the running water. § One of earths many cycles it is energized by the sun and circulates all of the earths life giving water.

§ Bedrock Breakup § Occurs in 2 ways. § Mechanical means– Using sand gravels

§ Bedrock Breakup § Occurs in 2 ways. § Mechanical means– Using sand gravels and small rocks the water grinds at the bedrock. Boulders are also used as cutting tools. § This grinding action is called Abrasion. § Abrasion—also causes the cutting tools to be worn down. Especially at their edges.

Cutting Tools can be very small and as big as cars.

Cutting Tools can be very small and as big as cars.

§ Chemical Means-- § Consists of dissolving soluble minerals limestone and marble and sandstones

§ Chemical Means-- § Consists of dissolving soluble minerals limestone and marble and sandstones that are held together with calcite cements. § Rivers flowing over such rocks form pits and holes in the bed rock.

§ Transportation § Rivers carry rock materials in 3 ways. § 1. Solution– dissolved

§ Transportation § Rivers carry rock materials in 3 ways. § 1. Solution– dissolved materials from bedrock. Ex. Calcium , magnesium § 2. Suspension– includes clay, silt, and fine sand. Although these materials are heavier than water they are stirred up and kept from settling on the bottom by the water moving. § 3. Bed load– Sediment moved along the stream bottom. Ex large cobbles and boulders.

§ Load Of the stream § Estimate what percent of the load of the

§ Load Of the stream § Estimate what percent of the load of the stream is solution suspension and bed load. § Solution 25% § Suspension 50% § Bed Load 25% § Note– in General the suspended load increases with human activity.

§ Carrying Power § Is indicated by both the total amount of sediment in

§ Carrying Power § Is indicated by both the total amount of sediment in the stream and by the particle size being moved. § The carrying power depends upon the speed of the stream and its discharge. § Discharge § Is the volume of water flowing past a given point in the stream at a given time. § Expressed in CFS § Cubic feet per second.

Waterfalls and River Deposits § Potholes § As sand –pebbles and small boulders swirl

Waterfalls and River Deposits § Potholes § As sand –pebbles and small boulders swirl around in the turbulence of a stream they grind deep oval holes into the stream bed. § Very large potholes are called plunge pools. And form through abrasion or dissolving of minerals. § Found at the base of waterfalls.

§ Waterfalls § NOTE § Occur for many reasons 1. River may flow over

§ Waterfalls § NOTE § Occur for many reasons 1. River may flow over hard rock onto a softer one. 2. Glaciers erode one valley deeper then others coming into it. 3. Intrusions of igneous rock § Rapids and waterfalls are only temporary features of streams. § http: //www. youtube. com/watch ? v=_HFmx. Ric. X 4 o

Harder Rock. More Resistant Softer Rock

Harder Rock. More Resistant Softer Rock

§ Undermining § Erosion of the base of the water fall leaves an overhang

§ Undermining § Erosion of the base of the water fall leaves an overhang that is susceptible to falling off. § From time to time pieces break off the top of the fall and thus it recedes farther upstream.

§ Meanders § A series of broad curves in the stream bed. § Form

§ Meanders § A series of broad curves in the stream bed. § Form when water moves slowly across a wide flood zone. § Also forms oxbow lakes and cutt offs from the river channel.

Creation of a Meander and cut offs and ox bow lakes. Flow direction

Creation of a Meander and cut offs and ox bow lakes. Flow direction

Formation of Meanders

Formation of Meanders

Point bar deposits

Point bar deposits

Formation of an Oxbow

Formation of an Oxbow

Cut bank erosion Point bar deposits } Meander loop

Cut bank erosion Point bar deposits } Meander loop

River Deposition § Speed of the river § Dictates how much and what size

River Deposition § Speed of the river § Dictates how much and what size sediments fall out of the moving water. § Greatest loss of speed is when a river flows into a standing body of water. Or the water source is cut off. § Identify an example in nature when a river would loose water.

Answer: Loss of both discharge and speed This is a photo of a car

Answer: Loss of both discharge and speed This is a photo of a car buried in flood sediments. Question : Why does a river leave so much sediment on its valley floor after a flood?

Deltas - Distribution Systems

Deltas - Distribution Systems

Alluvial Fans Transition in speed.

Alluvial Fans Transition in speed.

Assignment: Complete the following. 1. Explain How running water gets its energy from the

Assignment: Complete the following. 1. Explain How running water gets its energy from the sun. 2. Describe ways– in which running water breaks up bedrock. And how running water transports rock material. 3. Discuss the relationship between stream speed, discharge and carrying power. 4. Draw a diagram and explain how a waterfall occurs and how it migrates. 5. Explain the origin of the following: use a diagram to help you in your explanation. 6. § Meanders, flood plains, cut offs, oxbow lakes, Deltas and alluvial fans.

The River Valley The “V” shaped valleys are typical of young streams and river

The River Valley The “V” shaped valleys are typical of young streams and river systems. They occur this way due to the fact that young streams tend to flow at higher speeds which easily scour the stream bed. Steep valleys are called canyons, gorges, or chasms. How long does it take to cut a deep canyon?

Depends… Kind of bed rock. The amount of water. The amount of sediments. Base

Depends… Kind of bed rock. The amount of water. The amount of sediments. Base Level A stream con not cut its bed any lower than the level of the stream river or body of water into which it flows. Ex. Streams that flow into the ocean the base level is sea level. What would the Boise river’s “base level be”?

As a stream approaches its base level, the slope of the streambed and the

As a stream approaches its base level, the slope of the streambed and the speed of the stream decreases. As a result the streambed weathers slower and slower. At the same time the valley walls are being eroded and weathered by tributary streams. The Final result is a wider river valley. If vegetation is removed by natural or man caused methods this sets up a dangerous situation in nature.

Drainage Basin Or water shed. Includes all the land that drains into the river,

Drainage Basin Or water shed. Includes all the land that drains into the river, either directly or through its tributaries. What is the largest single drainage basin in the US? ? ? Mississippi River drainage Basin. What is the largest basin in the world?

Erosion Poster Guidelines Bold Title Catchy subtitle Include five topics about your type of

Erosion Poster Guidelines Bold Title Catchy subtitle Include five topics about your type of erosion Three diagrams illustrating agent processes Colored Sketch or create digitally Erosion Types: • Mechanical vs. Chemical Weathering • Stream Erosion • Wind Erosion • Glacier Erosion

Erosion Poster Project Black Textbook. Streams- pg. 168 Glaciers- pg. 190 Wind- pg. 210

Erosion Poster Project Black Textbook. Streams- pg. 168 Glaciers- pg. 190 Wind- pg. 210 Red Textbook. Streams- pg. 272 Glaciers- pg. 291 Wind- pg. 301

Stream Carrying Capacity Review Black Text Book Pg. 176 - 5, 6 Pg. 182

Stream Carrying Capacity Review Black Text Book Pg. 176 - 5, 6 Pg. 182 - 13, 15 Pg. 185 - 16, 17, 19