back to index ofchapters1. Name three forces that shape coastlines.
Ans. Rivers, wind and waves.
2. Name seven basic coastal features.
Ans. Seven basic coastal features are sandy beaches, river entrances,rocky headlands, mangrove wetlands, offshore islands, coral reefs and fiords.
3. Why does the size and shape of sandy beaches vary?
Ans. The size and shape of sandy beaches varies between seasons. Generally,larger winter waves erode beaches by washing sand out to form offshore sandbanks. Gentler summer waves then move the sand back on shore to rebuildthe beach. The dunes therefore provide a reserve of sand in winter and preventsand blowing inland during summer.
4. Define plant succession.
Ans. In a succession, small simple pioneer plants colonise a barren area,either bare rock or sand, and establish themselves by adapting to localconditions. In doing this, they improve the soil and prepare it for morecomplex plants to colonise the area, which in turn, prepare for the nextgroup and so on, right up to large trees in a dense forest.
5. What are dunes?
Ans. Mounds of sand.
6. Draw a colour diagram for each of the following:
a. Plant succession on an ideal sand dune
Ans. See Figure 104.1
b. The effect of building training walls on sand movement
Ans. See Figure 105.2
c. Formation of caves, arches and stacks
Ans. See Figure 106.1
d. Zonation in wetlands
Ans. See Figure 107.3.
e. How an offshore island forms
Ans. See Figure 108.1
f. Comparison of ribbon, patch and fringing shelf reefs
Ans. See Figure 109.3
g. Stages of glacial formation
Ans. See Figure 110.1
7. What happens to a dune when the plants are removed?
Ans. The sand blows away.
8. Why are training walls a problem?
Ans. They stop the flow of sand in a longshore drift.
9. What is a groyne?
Ans. Boulders that jut out to sea
10. Why are rocky headlands not a popular place for recreational activities?
Ans. Rocky headlands are not as popular with most people as sandy beachesbecause they are dangerous and often inaccessible. Waves breaking directlyon the rocky cliff face rule out any swimming or boating activity and thelimited rough surface available is unsuitable for normal beach activitiessuch as ball games. However, there are many exciting things to do on rockyheadlands, including sightseeing and action adventure activities.
11. What adventure activities can be done on a rocky coastline?
Ans. Hang-glidering, enjoy scenery, surfing, rockfishing .
12. Write down the names of the three zones on a rocky shore and foreach, describe the tidal limits and the types of animals and plants foundthere.
Ans. The wave cut platform can be divided up into the supra-littoral,littoral and sub-littoral zones.
· The supra-littoral or splash zone is above the high tide mark.It only gets wet when spring tides combine with large ocean swells. Simpleland plants, scattered insects and mobile animals inhabit this zone.
· The littoral zone is between the high and low tide marks. Differentparts of the zone are covered in water for various amounts of time, forexample, for 4 hours a day at the high tide mark and 20 hours a day at thelow tide mark. Barnacles, mussels, crabs, anemones and seaweed are someof the organisms that inhabit this zone.
· The sub-littoral zone is below low tide mark and is always coveredin water, except during a special spring tide. A large range of marine organismsinhabit this zone including brown, red and green seaweeds; worms; variousshellfish; starfish, sea urchins, octopi, shrimps, zooplankton and smallfish. In colder waters, the sub-littoral zone supports a huge diversityof life where large kelp forests grow as shown in Figure .1.
14. What is submergence?
Ans. Hundred of thousands of years ago, the sea level was much lowerthan it is now and many of the rivers we use now for boating and swimminghad steep-sided cliffs and ran through mountain valleys. However, climatechange raised the water level and the river valleys filled with water (calledsubmergence). The higher water level and subsequent wave action turned thehilltops nearer the sea into offshore islands
15. How are volcanic islands formed?
Ans. Volcanic island form from oceanic reefs which are important to Pacificisland people because they protect villages and towns from cyclonic waves,provide a basic food supply, a cradle for basic marine biodiversity in oceanfood chains and attract tourists.
Oceanic reefs are found around islands which have formed from volcanoesthat blast their way to the sea surface from weaknesses or hot spots inthe sea floor (Figure 109.1).
16. Name three types of shelf reef.
Ans. A ribbon reef is an elongated reef with its long axis parallel tothe edge of the continental shelf or coastline (Figure 109.3). The reeffront and algal rim are on the seaward side, grading into reef flat andfinally to the reef back on the leeward side. Water flowing through gapsbetween reefs brings nutrients and promotes reef growth along the bordersof these gaps.
Fringing reefs can be found growing around continental islands or alongmainland shores. A continental island is really an underwater mountain withits peak above the sea's surface. Corals and marine plants (algae) may settleand grow in the shallow waters around the peak, forming a fringing reef.
Patch reefs grow up from the continental shelf and accumulate sand anddebris in which plants grow. They contain a lagoon and a reef crest thatsupport an enormous amount of life. Patch reefs are very fragile geologicalstructures so special management conservation plans have been put in placeto protect them.
17. How is an atoll formed?
Ans. See Figure 109.2.
18. What is a fiord and how does one form?
Ans. Hundreds of thousands of years ago, glaciers carved out steep-sidedvalleys as they slowly moved towards the sea. When the sea-level rose andthe glaciers melted, the valleys filled with sea and became known as fiords.Figure 110.1 shows how the fiords of New Zealand were made.
Diving deeper - some suggested answers
This information is also published for students on the Internet site:
http://www.wetpaper.com.au/student
1. Find out about plate tectonics and how the islands of the Pacificmove about.
See Marine Studies Chapter 13
2. Ask your teacher to find a marine studies camp school and organisea coastlines appreciation tour that includes bike riding, snorkelling, sailingor surfing.
Contact your local MTA