Rocks and the Rock Cycle

Question 1

Where are sedimentary rocks formed?

Answer 1

Near the surface of the earth.

Question 2

Where can sedimentary rocks form?

Answer 2

Land, lake beds and beneath the sea

Question 3

What are the layers in sedimentary rock called?

Answer 3

Strata

Question 4

What process converts sediment layers into solid rock?

Answer 4

Lithification

Question 5

What two ways does lithification occur?

Answer 5

• Compaction

- Cementation

Question 6

Describe compaction.

Answer 6

As the grains are squeezed together by the weight of overlying sediments

Question 7

Describe cementation.

Answer 7

As individual particles are bonded to one another by a cementing agent such as silica or calcium.

Question 8

What are the three types of sedimentary rocks?

Answer 8

• Inorganic sedimentary rocks
• Organic sedimentary rocks
• Chemical sedimentary rocks

Question 9

How are inorganic sedimentary rocks formed?

Answer 9

Are formed from sediments that were broken down by weathering and erosion of pre-existing rocks.

Question 10

Name two common sedimentary rocks.

Answer 10

Sandstones and conglomerates

Question 11

How are organic sedimentary rocks formed?

Answer 11

Are formed from the sediments that came from once living organisms, such as plants and sea creatures.

Question 12

Name two common organic sedimentary rocks.

Answer 12

Limestone and coal

Question 13

How are chemical sedimentary rocks formed?

Answer 13

Are formed from material that was carried in solution in lakes and seas.

Question 14

Name two common chemical sedimentary rocks.

Answer 14

Gypsum and rock salt.

Question 15

Give an example of a coarse-grained inorganic rock?

Answer 15

Sandstone

Question 16

How is sandstone formed?

Answer 16

Formed when grains of quartz were deposited in layers on land or on the bed of a shallow sea.

Question 17

What is quartz?

Answer 17

Sand particles

Question 18

What two ways can deposits of quartz accumulate?

Answer 18

• Flood deposits

- Wind deposits

Question 19

When was sandstone created in Ireland?

Answer 19

Roughly 350 million years ago.

Question 20

What caused the sandstone to form in Ireland?

Answer 20

It was a result of flash flooding.

Question 21

What happened to the Caledonian mountains?

Answer 21

Heavy rainfall eroded them, washing the eroded sediments into the bed of a shallow sea.

Question 22

What does this sea bed make up now?

Answer 22

Much of the Munster Landscape

Question 23

What did the sandstone contain?

Answer 23

High levels of iron oxide- gave it a reddish appearance

Question 24

What substances helped bond the sediments together?

Answer 24

Iron and silica

Question 25

What is this sandstone called?

Answer 25

Old Red Sandstone

Question 26

How long did the old red sandstone remain submerged in the shallow sea?

Answer 26

Until approximately 250 million years ago.

Question 27

How was the sandstone moved up from the sea bed?

Answer 27

The African and Eurasian plates collided- causing the layers of sandstone and overlying limestone to buckle and uplifted.

Question 28

What were the newly formed Munster mountains called?

Answer 28

The Armorican Mountains.

Question 29

What did this process of folding create?

Answer 29

Parallel ridges of sandstone and valleys of limestone

Question 30

What happened to the limestone valleys?

Answer 30

They were weathered and eroded downwards creating flat, fertile land between the ridge mountains

Question 31

What has happened to form dolomite?

Answer 31

It has undergone a chemical change

Question 32

What chemical change occurred in dolomite?

Answer 32

The calcium has been replaced by magnesium

Question 33

What colour is dolomite?

Answer 33

Varies in colour from white to grey or pink

Question 34

Where is dolomite found in Ireland?

Answer 34

Found among the limestone of the south of Ireland

Question 35

What is chalk?

Answer 35

Pure, soft, white-coloured limestone

Question 36

Where did it used to be found?

Answer 36

It once covered Ireland, but it has been eroded.

Question 37

Where has the chalk not been eroded?

Answer 37

The Antrim-Derry Plateau, where it is protected by a layer of basalt

Question 38

What is limestone an example of?

Answer 38

An organic rock

Question 39

How is limestone formed?

Answer 39

From the compressed remains of sea creatures.