igneous volcanic 2 2

plutonic

11.. 3 3.. 4 4..

foliated

55..

non-foliated

66..

metamorphic

detrital

77.. 8 8.. 9 9..

sedimentary

chemical

1100.. 1 111.. 1 122..

organic

1133.. 1 144.. 877310 _ 0100-0107.qxd 4/8/08 12:36 Página 104

105 ROCKS

WORKSHEET 4

11

NAME: CLASS: DATE:

Woorrkk iinn ppaaiirrss.. CCoommpplleettee tthhee tteexxtt wwiitthh tthhee wwoorrddss bbeellooww..

1 1

Thhee rroocckk ccyyccllee

Rocks are broken up by atmospheric phenomena (changes in temperature, rain, acid rain and wind) or by the activities of plants and animals. This is called

1.. . The broken fragments of rocks are swept away

by running waters, glaciers, waves or winds. This process is called

2.. .

Two processes join fragments to form rocks. In sedimentary rocks, the weight of layers of sediment compacts the sediments more, which reduces the spaces between the fragments and squeezes out the water.

This is called 33.. . The rock fragments are stuck together with salt crystals which form when the water is eliminated, a process called 44.. , and layers of sediment become layers –or strata– of sedimentary rock.

Organic material is transformed into two types of sedimentary rock.. 55.. is made of terrestrial vegetation which accumulated in swamps and was buried in the Earth’s crust millions of years ago.

6.. is made of marine plant and animal remains which fell to the bottom of the sea

and were buried under sediments that accumulated over millions of years. Other rocks are formed within the Earth by the effect of intense heat and pressure on sedimentary and igneousrocks. These are called

7.. rocks. When they eventually come to the surface, they can also suffer weathering

and erosion.

And so the rock cycle starts again.

Onn aa sseeppaarraattee sshheeeett ooff ppaappeerr,, ddrraaww aanndd llaabbeell tthhee ssttaaggeess ooff tthhee rroocckk ccyyccllee..

IInn ppaaiirrss,, tthhiinnkk aabboouutt aanndd aannsswweerr tthhee qquueessttiioonnss.. 1

1.. Why are coal and oil called ‘organic’ sedimentary rocks?

2.. Why are they rocks although they are not inorganic?

3.. How do metamorphic rocks eventually emerge to the surface?

3 3 2 2 _ _____ // 2200

cementation coal weathering metamorphic oil erosion compaction.

ROCKS

WORKSHEET 5

11

NAME: CLASS: DATE:

Find words or expressions in the text which mean the following. a. broken:

b. peoples from Central America: c. jewel:

d. unusual: e. shiny:

Would you expect to find fossils in obsidian? Explain your answer.

Give one example of the use of obsidian in the ancient world and one in the modern world.

What is the main difference between an obsidian blade and a steel blade? How can you see this difference?

Draw and label a ‘macuahuitl’ as you imagine it. Then check your answer in an encyclopedia or on the Internet. 5 4 3 2 1 ___ / 10 Obsidian

This mysterious and beautiful rock is also known as ‘natural glass’

or ‘volcanic glass’. It is formed when boiling lava from a volcano cools rapidly, without sufficient time for crystals to form. Stone Age cultures valued obsidian highly because it could be fractured to produce sharp blades or arrowheads. When polished, it created early mirrors, tools, statues and decorative objects. Pre-Columbian Mesoamericans also made a type of sword with obsidian blades mounted in a wooden handle. Called a ‘macuahuitl’, the weapon could inflict terrible injuries. Native American people traded obsidian throughout North America.

Today, obsidian is used in cardiac surgery because well-made obsidian blades

are much sharper than steel surgical scalpels. Even the sharpest metal knife has an irregular blade when viewed under an electron microscope. However, an obsidian blade is smooth and even. Obsidian is also used for ornamental purposes and as a gemstone. It possesses the peculiar property of presenting a different appearance according to the manner in which it is cut. When cut in one direction it is a beautiful jet black; when cut across another direction it is a glistening grey. 877310 _ 0100-0107.qxd 22/8/08 07:58 Página 106

107 ROCKS

TEST 11

11

NAME: CLASS: DATE:

Ciirrccllee tthhee ccoorrrreecctt aannsswweerr.. 1

1.. Cement is made from (a) gypsum (b) limestone and clays (c) granite fragments. 2

2.. Rock salt and quartzite are (a) monomineralic rocks (b) metamorphic rocks (c) sedimentary rocks. 3

3.. Rocks formed from cooled magma are called (a) conglomerate rocks (b) intrusive rocks

4.. Limestone is a ____________ (a) detrital (b) chemical (c) organic rock. 5

5.. Fossil fuels are (a) organic (b) detrital (c) chemical. 6

6.. The first step in the rock cycle is (a) weathering (b) compaction (c) cementation. 7

7.. Magma on the Earth’s surface is called (a) pumice (b) crust (c) lava. 8

8.. In plutonic rocks, the magma (a) cools rapidly, producing tiny crystals (b) cools slowly, producing large

crystals (c) cools rapidly, trapping gases which produces bubble holes.

9.. Metamorphism occurs (a) near the Earth’s crust (b) deep within the Earth (c) near active volcanoes. 1

100.. Metamorphic rocks are formed when (a) sedimentary rocks melt (b) metamorphic rocks lose their

minerals (c) minerals inside rocks are changed by heat and pressure.

Reeaadd tthhee tteexxtt aanndd aannsswweerr tthhee qquueessttiioonnss..

1.. During which process were fossils created? How?

2.. What is the relationship between a trilobite and a modern lobster?

3.. Find words or expressions in the text which mean the following. a

a.. important: cc.. demostrated:

b.. proved: dd.. plants and trees:

4.. Put these living things in the order in which they appeared on Earth, starting with the earliest: dinosaurs, molecules, mankind, plants and trees, molluscs and trilobites, fish.

2 2 1 1 _ _____ // 2200 Fossils

Sedimentary rocks sometimes contain remains of living things that died millions of years ago. These remains are called fossils. Fossils became part of the rocks during the processes of compaction and cementation of sediments, and they provide invaluable information about the history of life on Earth.

The first fossils date back to about 540 million years ago. They were molluscs and trilobites. Trilobites had a head, a thorax and a tail. In the nineteenth century, scientists established that trilobites were arthropods, the group that includes modern insects and crustaceans.

Later fossils showed the first fish, and then the first vegetation that appeared on Earth. And much, much later, of course, came those strange and mysterious ‘terrible lizards’, the dinosaurs.

In document Science 1 (Page 104-108)