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Erosion & Running Water: River Deltas

Erosion & Running Water: River Deltas. World Geo 3200/3202 October 2010. Introduction. In this lesson you will: 1.3.4 Explain how deltas are formed. (k) 1.3.5 Contrast the terms arcuate delta, digitate delta, and estuarine delta. (k). Deltas: Definiton.

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Erosion & Running Water: River Deltas

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  1. Erosion & Running Water: River Deltas World Geo 3200/3202 October 2010

  2. Introduction • In this lesson you will: • 1.3.4 Explain how deltas are formed. (k) • 1.3.5 Contrast the terms arcuate delta, digitate delta, and estuarine delta. (k)

  3. Deltas: Definiton • Delta is a low lying area at mouth of river formed by deposition of silt deposition occurs because river slows as it enters ocean or lake.

  4. How Deltas Form • As a river is moving, it carries eroded material with it. The eroded material continues to flow downstream until it reaches still water if an ocean, sea, lake, or bay. • When the river reaches the still water, the heavy particles are first to settle out. • The lighter particles are carried further from shore. This process is then repeated farther out and a delta forms.

  5. Types of Deltas • Arcuate • Digitate • Estuarine

  6. 1. Arcuate Delta • Curved in the shape of a bow. • Fan shaped • To the right is a satellite photo of the Nile Delta, notice the fan shape on the right-hand side of the mount of the river.

  7. 2. Digitate Delta • Delta with long fingers of sediment reaching into the sea • To the right is a satellite photo of the Mississippi Delta (p. 32), notice that it runs out into the Gulf of Mexico like a finger - unlike the Nile Delta.

  8. 3. Estuarine Delta • Formed when rivers runs into a bay or estuary • Created by sediment deposited from river outflow and from tidal inflow • Tidal mud flats form and can be seen at low tide • The Seine River Delta depicted in figure 2.12 on p. 32 of your book is a good example.

  9. 3. Estuarine Delta • To the right is a satellite photo of the Amazon Delta, notice the tidal flats or islands that cover and uncover with the tide. • This picture below shows a small estuarine delta in Notre Dame Bay.

  10. Delta Review • Read “Erosion and Deposition Process" on page 30-32 of your text and complete the following: • The term given to the low lying land at the mouth of a river. Silt is deposited there. • The term given to a fan shaped delta. • The name give to a finger shaped delta • The name given to a delta that forms in a bay or estuary. • Why does so much deposition occur at the delta of a river?

  11. Delta Review • The term given to the low lying land at the mouth of a river. Silt is deposited there.  DELTA • The term given to a fan shaped delta. ARCUATE • The name give to a finger shaped delta DIGITATE • The name given to a delta that forms in a bay or estuary. ESTUARINE • Why does so much deposition occur at the delta of a river? THE FLOW RATE SLOWS BECAUSE THE WATER ENTERS A LAKE OR OCEAN> THE SLOWER MOVING WATER DROPS THE SILT

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