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Concept evaluations by chapter

CHAPTER 6 ANSWER KEY

The lithosphere and the hydrosphere

1. Quartz is also known as rock crystal. The expression is a good description of the nature of quartz. a) In which category of substances would you classify quartz? Quartz is a mineral.

b) What characteristics of this type of substance are suggested by the word crystal? The word crystal suggests that the mineral has a specific shape and is consistently composed of the same chemical elements with well-defined properties.

c) What aspect of this type of substance does the word rock point to? It points to the natural and inorganic origins of the mineral—the fact that it exists naturally in the earth.

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2. A student took the following notes during a presentation of various minerals from a collection: – Galena is lead sulphide. It is dark grey. Its streak is grey like a pencil marking. Metallic lead is extracted from it. Its ore often contains silver. – Sphalerite is zinc sulphide. The mineral can be brown, black and sometimes yellow. Its streak is dark brown. Zinc is extracted from it. Its ore almost always contains iron. – Corundum is an aluminum oxide. It comes in various colours. It can be transparent, translucent or opaque. Its streak is very pale. Rubies and sapphires are varieties of

d corundum. e t t i m r – Fluorite is calcium fluoride. It can be colourless, white, yellow, blue, green, purple, red or e . p y r n

o brown. Its streak is colourless or very slightly tinted. Some varieties are used to make o t i t a a v t r optical instruments. p e a s d b a O

– Pyrite is iron sulphide. It is a light brassy yellow and is sometimes iridescent. Its streak is d h n t i a

black. It is nicknamed fool’s gold. n e o i s t u c u m d a) Classify these minerals into two categories based on the properties described. Explain your o o r o r p s e classification. s R a

o Galena, sphalerite and pyrite are idiochromatic minerals. They have a characteristic colour, and f

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© s their streak is consistently dark, which is also characteristic of idiochromatic minerals. Corundum and fluorite are allochromatic minerals. They come in various colours and leave a very pale streak, which is a characteristic of allochromatic minerals.

1 Observatory / CHAPTER 6 Guide ANSWER KEY Concept evaluations by chapter The lithosphere and the hydrosphere 11129-B Name: Group: Date: :

b) What characteristic property was not included in the mineral descriptions? The minerals’ hardness was not described.

c) What is the difference between a transparent mineral and a translucent mineral? Transparent minerals let light pass straight through them, so it is possible to see an object through them. Although translucent minerals let light through, it is impossible to distinguish an object through them.

[______/6] 3. During a lab experiment, you are given the following materials: a steel knife, a one-cent coin and five minerals, labelled A, B, C, D and E. You are asked to classify the minerals in descending order of hardness. Your lab team obtains the following results: – Mineral A is easily scratched with the knife, but barely scratched with the coin. – Mineral B cannot be scratched with the knife. – Mineral C is easily scratched with the coin. – Using mineral D, the coin can be scratched with difficulty, but scratching the knife blade is impossible. – Mineral E can be scratched very slightly with the knife. The coin was easily scratched with mineral E. a) Write and explain your classification. The minerals, in descending order of hardness, are B, E, D, A and C. The knife blade is harder than the coin because it was possible to scratch the coin with mineral D, but not the blade. The hardest mineral is B because it cannot be scratched with the blade. It is harder than steel (the

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blade material). r e . p y r n o o t i t The second-hardest mineral is E because it can be scratched slightly with the knife but can be a a v t r p e a s d b a O used to scratch the coin (so it is harder than the coin).

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Mineral D can be used to scratch the coin (barely) but not the knife, so it is only slightly harder i s t u c

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than the coin. r p s e s R a

Mineral A is easily scratched with the knife but barely scratched with the coin, so it is not quite as r P o f

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hard as the coin. o © s Mineral C is easily scratched with the coin, so it is not as hard as the coin.

2 CHAPTER 6 Observatory / The lithosphere and the hydrosphere Concept evaluations by chapter ANSWER KEY Guide 11129-B Name: Group: Date: :

b) Diamonds are not only prized by jewellers; they are also used to cut the glass for doors and windows. Which property of this substance makes it suitable for such a purpose? Explain your answer. Diamond can cut glass because it has a hardness of 10, which is higher than the hardness of glass. The glass is scored, to weaken it, and then cut.

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4. For the past few years, a team of geologists has been prospecting for diamonds at a site 200 km east of James Bay (Baie James). Access to the site is by helicopter only. A recent report by the geologists to the mining company executive recommends the construction of a road approximately 150 km long so that diamonds of exceptional quality can be mined.

The company, which has already taken care to obtain the support of the Aboriginal communities in the region, approaches the different levels of governments so that the road can be built. a) What is the first phase of building a mine, which the geologists have already carried out? The first phase of mining is locating a deposit.

b) What findings motivate geologists to recommend the development of a mine at a certain site? Geologists base their recommendations on the amount and concentration of the mineral at the site.

c) What is a feasible site for a mine called (sufficient amounts and concentration of the mineral)? A feasible site is referred to as a deposit. d e t t i

m d) What are the two possible forms of mining? r e . p y r n

o The two possible forms of mining are open-pit mining and underground mining with subterranean o t i t a a v t r p e a s d b passages. a O

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w n e o i s ______t [ u c u m d o o /6] r o r p s e s R a

r 5. Which one of the following five substances does not belong to the group? Explain your answer. P o f

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o a) calcite b) talc c) slate d) apatite e) topaz © s Slate does not belong. All the other substances are minerals, whose composition and properties are always the same. Slate, on the other hand, is a metamorphic rock whose composition and properties vary depending on the composition of the clay it is made of.

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6. What am I? a) a natural substance composed of many different minerals Rock b) an inorganic substance existing naturally in the ground Mineral c) the name given to different layers of soil Horizons d) the layer made up of the three main rock families Lithosphere

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7. Describe the similarity and the difference between each of the following pairs of rocks. a) granite and pumice Similarity: Granite and pumice are both igneous rocks, formed when volcanic magma solidifies.

Difference: Granite is an intrusive igneous rock; the magma solidifies before reaching the Earth’s surface. Pumice is an extrusive igneous rock; the rock solidifies at the surface, on contact with the air.

b) limestone and marble

Similarity: d e t t i m r

Limestone and marble are composed of the same elements because marble is made of limestone e . p y r n o o t i t a a that has been transformed by heat and pressure. v t r p e a s d b a O

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u m d o o r o r p s Difference: e s R a

r P Limestone is a sedimentary rock, formed by the accumulation of compressed sediment. Marble is o f

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a metamorphic rock, formed from limestone that has been transformed by heat and pressure. © s

4 CHAPTER 6 Observatory / The lithosphere and the hydrosphere Concept evaluations by chapter ANSWER KEY Guide 11129-B Name: Group: Date: :

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8. Look at the illustration opposite. a) Name each of the soil layers. Organic matter

Topsoil

Subsoil

Fragmented parent rock

Unaltered parent rock

b) At the student horticulturists’ market, they are selling 25-L bags of soil labelled “Garden soil.” Which soil layer is removed to fill these bags? Explain your answer. Topsoil is removed because it contains humus and water-soluble minerals that plants need to grow.

c) Some regions of Québec are known for being very fertile, while others are much less fertile even though they are exposed to the same climate. What are the three conditions for soil fertility? The three conditions for soil fertility are: – a sufficient amount of minerals – adequate moisture – an appropriate soil pH (for plant growth).

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9. To encourage her students to think about what they are learning, Jamie, a science teacher, e t t i m

gives them what she calls the “Day 4 puzzle.” r e . p y r n o o t i t a a v t Every Day 4, in the last few minutes of her class, Jamie writes a puzzle on the board for her r p e a s d b a

students to solve. O

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n e o i s The following are three examples of Jamie’s puzzles. Solve them. t u c

u m d o o r o r a) To explore northern Québec, Mr. Marchant takes a plane between the months of p s e s R a

September and May but takes a helicopter during the rest of the year. How do you explain c

r P o f his choice? R y l e l E

Northern Québec is covered in permafrost—ground that is permanently frozen between the © s months of September and May. Planes can land on runways during this period. During the other months of the year, however, the top layer of the permafrost (the active layer) thaws. It is no longer safe to land planes on the softened ground of the runways, so Mr. Marchant must take a helicopter, which can put down safely. 6 CHAPTER 6 Observatory / The lithosphere and the hydrosphere Concept evaluations by chapter ANSWER KEY Guide 11129-B Name: Group: Date: :

b) In Alberta, oil is currently being extracted from oil sands. What must there have been in Alberta millions of years ago? The presence of oil in oil sands tells us that the Alberta region was covered in a sea containing algae and marine animals. When they died, they were covered with sand and silt, and under pressure from the layers of sediment above them, they eventually turned into oil.

c) Iceland lies southeast of Greenland. Both are lands of glaciers, and both are at roughly the same latitude. However, the earliest Danish settlers all chose Iceland, and no one settled in Greenland. Explain your answer. Iceland lies in a volcanic region, while Greenland does not. In Iceland, the many geothermal springs prevented settlers from dying of cold and made it possible to grow crops and raise livestock.

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10. Developing countries require huge amounts of energy for their economic growth. Three of these countries—China, Russia and India—are gradually turning toward nuclear energy. China has nine plants under construction and plans to build 30 more by 2030. Russia expects to build two plants every year from 2010 onward. India currently has nine nuclear plants under construction. In the meantime, these countries depend on traditional energy resources to meet their needs. For example, China is 75-percent dependent on coal for its electricity production.

According to current predictions, oil reserves will be depleted within the next 100 years, coal will run out within 200 years, and uranium, within 500 years. a) Burning fossil fuels creates byproducts that cause environmental problems. Name three of

these byproducts and the problems they cause. d e t t i Carbon dioxide (CO2) is the principal greenhouse gas behind global warming. Sulphur dioxide m r e . p y r n o o t i (SO2) and nitrogen oxides (NOx) are pollutants responsible for acid rain. t a a v t r p e a s d b a O

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r b) What is the principal advantage for the world if these three developing countries use p s e s R a

l nuclear energy? Explain your answer. I c

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l The principal advantage is a significant drop in greenhouse gas emissions and a consequent e l E

o © s reduction in global warming. Since these three countries have huge energy needs, they burn tonnes and tonnes of fossil fuels and give off enormous amounts of greenhouse gases. A small amount of uranium would be enough to meet their needs, without the emission of any greenhouse gases.

c) Considering the risks associated with nuclear energy, the United States—the country with the greatest number of nuclear power plants in operation—voted a moratorium at the end of the 1970s, suspending the construction of any new plants. This moratorium has now been lifted, and soon new power plants will be built. What are the two main disadvantages of using nuclear energy? The two main, and major, disadvantages are the risk of a reactor exploding and the radioactivity of the waste from nuclear fission.

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11. The Rivière Etchemin watershed lies next to the Rivière Chaudière watershed. The two rivers follow almost parallel courses, flowing from south to north and emptying into the St. Lawrence River (Fleuve Saint-Laurent) near the Saint-Romuald district of Lévis. In spring or during heavy rain in summer, flooding of the Rivière Chaudière in Beauce often makes the headlines, but we rarely hear about any flooding of the Rivière Etchemin.

Identify three elements that may explain the difference in spring flooding between these two rivers. Explain your answers. Answers will vary. Examples: – If the Rivière Chaudière is narrower, its water level will rise more rapidly when the snow melts. – If the slope of the land bordering the Rivière Chaudière is steeper than the banks of the Rivière Etchemin, the snowmelt will make the water level rise more quickly. – If the vegetation on the banks of the Rivière Chaudière is less dense than on the banks of the Rivière Etchemin, the snowmelt will run off more rapidly into the Rivière Chaudière.

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R y 12. Refer to the diagram opposite to answer l e l E

o the following questions. © s a) Identify layers A, B and C. Layer A is the mixed layer. Layer B is the thermocline. Layer C is deep water. 8 CHAPTER 6 Observatory / The lithosphere and the hydrosphere Concept evaluations by chapter ANSWER KEY Guide 11129-B Name: Group: Date: :

b) With which region of the Earth can you associate this diagram? Explain your answer. It represents the part of the oceans near the equator because the temperature of the surface waters is 28°C.

c) The depth of layer A varies depending on turbulence. What factors affect turbulence? The factors affecting turbulence are waves, tides and wind.

d) Compare the changes in temperature between layers B and C. In layer B, the temperature drops very rapidly, from 28°C to 5°C, over a limited depth of about 800 m. In layer C, the temperature falls very slowly, from 5°C to 4°C, over a greater depth of about 4000 m.

e) At what temperature is water density at its maximum? Choose the correct answer and explain it.

A. 0°C B. 5°C C. 30°C D. 4°C Water density is at its maximum at 4°C (D). This is the temperature of water at the bottom of the ocean. The denser the water, the deeper it sinks.

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13. a) Which type of current is the Gulf Stream, and what causes it? The Gulf Stream is a surface current caused by the wind. d e t t i b) What is the movement of all surface and subsurface currents around the world called? m r e . p y

r Thermohaline circulation n o o t i t a a v t r p e a s

d c) What role does ocean circulation play? b a O

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a Ocean circulation plays a role in regulating the climate.

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R y l 14. Answer the following two questions. e l E

o © s a) What is the connection between the hydrosphere and the cryosphere? The cryosphere is a part of the hydrosphere; it is the frozen portion of the Earth’s waters. The hydrosphere is the Earth’s outer layer of water, uniting water in all its states.

b) Your friend Sam says that an iceberg floating on the ocean is a part of the pack ice. Is he right? Explain your answer. Sam is wrong because an iceberg is a piece of a9 glacier that has fallen into the sea. It is therefore Observatory / CHAPTER 6 Guidemade ANSWERup of frozen KEY water from theConcept land, whileevaluations pack by ice chapter is made up of frozenThe lithosphere seawater. and the hydrosphere 11129-B The proliferationaim is to prevent of algae. the eutrophication of rivers and lakes. Name: Group: Date: :

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10 CHAPTER 6 Observatory / The lithosphere and the hydrosphere Concept evaluations by chapter ANSWER KEY Guide 11129-B