1.5.4 Understand how ocean waves and currents change

coastlines. (Chapter 3)

Coastlines

Two general categories of coastlines:– 1.) Emerging: Water deepens rapidly. Steep banks,

as the coast rises up quickly. Fairly straight and rocky shore. Called a regular shoreline. No natural harbors

Emerging Coastlines: What they Shape…a review

• Erosion of headlands creates sea caves, sea arches and sea stacks

• Emerging coastlines straighten the coastline in much the same fashion as submerging coastlines.

2.) Submerged: Also know as drowned, embayed or ria coast. Gentle or gradual coastline. What were once river valleys produce an indented and irregular coastline

* 1.5.4 The processes straightens out an irregular coastline. (Submerging coastlines)

1. Weathering of Headland

What forces cause the weathering & erosion?

Hydraulic pressure Corrosion Abrasion

2. Transportation of silt

How is silt transported?

Longshore Drift Waves Currents

3. Deposition of silt Where does

deposition occur? Bay beaches;

filling inlets Bay bars; closing

off inlets

4. Summary: Submerged coasts straighten!

1.5.4 Define the terms bay beach, bay bar and spit. (P. 44-45)

Bay Beach An accumulation of sediment

in a bay that is deposited by waves and longshore drift.

Spit

•A ridge of sand running away from the coast, usually with a curved seaward end. Spit grows in the prevailing direction of longshore drift. Ends are curved by the action of waves in different directions

Bay Bar

•A ridge of mud sand or silt extending across a bay.

•Formed when spits stretch across the mouth of the bay

Spit

What can you tell about the direction of long shore drift?

Is there any indication a bay bar might form?

Bay Bar

Notice the spit has closed off the mouth of the harbor/bay

Would these be a tourist attraction or distraction?

Bay Beach

2. The point of land on top of the picture would be called?

1. Where does all the beach sand come from? Can you propose two sources?

1.5.4 Describe the three processes by which Waves erodes coastal areas. (same as rivers)

1. Hydraulic pressure is the pounding force of water and waves

2. Corrosion (formation of solutions) is the weathering of rock by chemical processes. Minerals such as calcium carbonate & limestone dissolve in water

3. Abrasion is an example of physical weathering. Rock & sand particles suspended in the water bump, grind, scrape & gouge surfaces the water hits

Analyze the processes that result in the straightening out of a regular and irregular coastline.

Similarities:– Emerging coastlines

straighten, due to erosion and weathering, as do submerging coastlines.

– Headlands are reduced in size.

Differences:– Erosion of headlands

creates sea caves, sea arches and sea stacks, instead of bay beaches, spits & bay bars.

Questions

Read pp.41-42 Do: Questions 11, 12 and 13a) Do:

– Page 25. Questions 2 and 3– Page 26. Question 4a– Page 28. Question 5– Page 29-30. Case Study. The Red River Flood of

1997. Questions 7a, b, c and d

Answers!

Page 42 Q11:

– A) Process causes waves bend?– Wave refraction– B) Where and Why?– Near shore and headlands– C) Concentrates erosion on the headlands

Q12:– Process causes waves to move eroded sediment

along shore?– Longshore drift

Q13A:– Land that juts out?– Headland

– Page 25. Questions 2 and 3– Q#2:– Solutions: Acids– Hydrolysis: Clay/silicates– Oxidation: Rust (red or green). AND weathering of

rock!

Page 25: Q#3 2.3 Exfoliation: Peeling layers of rock 2.4 Oxidation: Weathering of rock. (Page 25

note in text)

Page 26. Q#4A What is drainage basin? Rainwater absorbed by the soil that runs into a

river

Page 28: Q#5 Identify the river: Mature River: broad, flat, wide flood plain, large

meanders

Page 29-30. Case Study. The Red River Flood of 1997. Questions 7a, b, c and d

7A) Life stage? Mature or old. Broad meanders, flat floodplain

7B) Distinguish? Ancient lake with clay bottom. Narrow deep waters. Through Winnipeg, which increases run-off

7C) Human actions? $63 million floodway/dike 7D) Further protect? More dikes. Restricting construction.

Raising homes. Developing disaster plans. Justify opinion