SCIENCE EARTH SCIENCE TEST

Question 1

Wegner Theory

Answer 1

Alfred Wegener proposed that the continents were once united into a single supercontinent named Pangaea. He suggested that Pangaea broke up long ago and that the continents then moved to their current positions. He called his hypothesis continental drift.

Question 2

Sea-Floor Spreading

Answer 2

The process of new crust forming at the ocean ridges and spreading outwards

Question 3

The major tectonic plates

Answer 3

African plate
Pacific plate
Australian plate
Antarctica plate
Eurasian plate
Antarctic plate
North American plate
South American plate

Question 4

Hess’ Theory

Answer 4

50 years after Wegener proposed his theory, Harry Hess confirmed the theory by using the evidence of seafloor spreading to explain what moved continents.

Question 5

Magnetic Stripping

Answer 5

Magnetic striping: the patterns of magnetism trapped in rocks on each side of plate boundaries. When molten rock solidifies, all its magnetic particles line up with Earth’s magnetic field to point in the same
direction. The pattern of magnetism was symmetrical – the rocks at equal distances on each side of the ridge were formed at the same time and so had their magnetic fields pointing in the same direction. As Earth’s magnetic field changed over millions of years, so did the magnetic direction preserved in the rocks

Question 6

Age of the Sea-floor

Answer 6

The further the rocks of the Sea-floor were from the ridges, the older they were. The Sea-floor as very young compared with the rocks in the continents.

Question 7

Sediment Thickness

Answer 7

The sediment rock layers on the ocean floor become thicker as you move away from the ridges. This means that sediments had been falling for longer on the rocks on the sea floor further away from the ridges

Question 8

Convection Currents

Answer 8

Convection currents drive the movement of Earth’s rigid tectonic plates in the planet’s fluid molten mantle. In places where convection currents rise up toward the crust’s surface, tectonic plates move away from each other (Sea-floor spreading).

Question 9

Two Types of Crust

Answer 9

Oceanic Crust
Continental Crust

Question 10

Oceanic Crust

Answer 10

It is found on the ocean floor, below sea level. The oceanic crust is thinner, and denser than the continental crust due to the presence of iron and magnesium.

Question 11

Continental Crust

Answer 11

It is the crust that forms the continents. Contains lighter elements such as aluminium and silicon.

Question 12

Volcano

Answer 12

Is a place where extremely hot material from inside Earth erupts at Earth’s surface. Materials can include:
Gas (Steam and hydrogen sulfide)
Ash
Lava
Lumps of solid volcanic rock such as scoria

Question 13

Earthquake

Answer 13

An earthquake is the rapid movement of the ground, usually back and forth and up and down in a wave motion. Caused by the rapid release of energy as the tectonic plates move.

Question 14

Detecting Earthquakes

Answer 14

Earthquakes are detected by using an insturment called a seismometer.

Question 15

Seismic Waves

Answer 15

The movement of the ground in an earthquake occurs in a shaking back and forth motion called a wave. These waves are known as called seismic waves. There are three main types of seismic waves.

Question 16

Primary Wave

Answer 16

Longitudinal waves that travel fast through the earth. Longitudinal waves move the ground back and forth.

Question 17

Primary Wave

Answer 17

Longitudinal waves that travel fast through the earth. Longitudinal waves move the ground back and forth.

Question 18

Secondary Waves

Answer 18

Are transverse waves that travel slightly slower than primary waves through Earth. Transverse waves move the ground up and down.

Question 19

Surface Waves

Answer 19

Are the slowest waves and cause the most destruction.

Question 20

Crust

Answer 20

The crust is the Earth’s outermost solid layer. It makes up our mountains and plains and makes up the floors of our ocean and seas. The crust varies in thickness from about 5km under the oceans to about 30km under the continents. The crust is split into sections known as tectonic plates.

Question 21

Rifting

Answer 21

Rifting is the process of continents breaking up, subsiding and allowing in water from the sea.

Question 22

Divergent Plate Boundaries

Answer 22

Where plates are moving away from each other in opposite directions. Aalso known as constructive boundaries. When the plates separate they leave a rift between them. The mid-ocean ridge forms a diverging boundary the ridge is the evidence that new curst is being constructed. Diverging boundaries also occur on land.

Question 23

Converging Boundaries

Answer 23

Where plates are colliding with each other. They are also known as destructive boundaries. Rock is destroyed at converging boundaries. These collisions make all sorts of land features such as mountains, chains of island and underwater trenches.

Question 24

Transform Boundaries

Answer 24

*Where plates are sliding parallel to each other but in opposite directions.

Question 25

Subduction

Answer 25

When one plate sinks below another plate during a collision.

Question 26

GPlates

Answer 26

A tectonic reconstruction software, which helps us visualiser the earthe’s crust.

Question 27

Three ways GPlates help us

Answer 27

-Opal Prospectors use GPlates to find opal fields
-Scientists use GPlates in their research.
-Helps us predict the changes on the Earth’s surface in the future.

Question 28

Volcanoes and plate boundaries

Answer 28

Most volcanoes are found at or near plate boundaries. This is because the movement of the plates create weakness in the crust and also generates intense heat that can melt rock.

Question 29

Earthquakes and plate boundaries

Answer 29

Most earthquakes start at the edge of a tectonic plate.