The Changing Earth

Question 1

What are the four layers of the earth, in order?

Answer 1

Crust, mantle, outer core, inner core

Question 2

Describe the crust

Answer 2

Outer layer, solid, thinnest layer, 10-80km thick, 2 types- oceanic and continental, contains rocks and minerals

Question 3

Describe the mantle

Answer 3

thickest layer (2900 km), made of very hot solid rock that can flow, gooey (plastic like), drives the movement of Earth’s continents which sit on plates on the mantle.

Question 4

Describe the outer core

Answer 4

liquid, (2300 km thick), made of metals- iron and nickel, where the magnetic field comes from (detected by compasses)

Question 5

Describe the inner core

Answer 5

1220 km, 6000 degrees c, made mainly of iron and nickel, pressure (gravity) from the layers above squeezes it into a solid sphere

Question 6

Identify the location of the asthenosphere

Answer 6

Asthenosphere is the upper mantle, just below the crust

Question 7

Identify the four spheres of the Earth

Answer 7

Lithosphere, atmosphere, hydrosphere, biosphere

Question 8

Describe the Lithosphere

Answer 8

(crust), solid outer layer of the earth, divided into tectonic plates; continental and oceanic

Question 9

Describe the Atmosphere

Answer 9

envelope of gases surrounding the earth

Question 10

Describe the Hydrosphere

Answer 10

all water on the Earth’s surface such as lakes and seas but sometimes including water above the surface like clouds.

Question 11

Describe the Biosphere

Answer 11

Regions of the surface and atmosphere of the earth occupied by living organisms

Question 12

Outline the theory of Continental Drift by Alfred Wegener

Answer 12

Proposed in 1915, the theory that the continents were once joined as a SUPERCONTINENT called Pangea but had moved apart. This split into two smaller continents called Gondwana and Laurasia

Question 13

Identify the supercontinents

Answer 13

Pangea, Gondwana and Laurasia

Question 14

Outline the theory of plate tectonics

Answer 14

The theory that Earth’s land masses are in constant motion. It states that Earth’s outer layer (lithosphere) is divided into more than 15 massive pieces called Tectonic plates. These plates move around the asthenosphere (upper mantle) interacting at boundaries, shifting the continents which sit on the plates and producing new landforms.

Question 15

Identify that the earth consists of huge cracked tectonic plates that are larger than the continents.

Answer 15

yes

Question 16

Outline the evidence for the theory of Plate Tectonics

Answer 16

Continental drift is a large piece of evidence because without the plates, the continents wouldn’t be able to move. Earthquakes along plate boundaries called fault lines, similar fossils and rocks on seperate continents, and matching shapes of continents that look to fit together as a jigsaw puzzle and once a large continent.

Question 17

Explain how the Earth’s plates move as a result of convection currents in the mantle and as a result of gravitational forces

Answer 17

heat from the core makes magma in the mantle rise toward the crust. As the hot current nears the crust, it begins to cool and sink back towards the core. As the magma sinks, it drags the plates across the surface of the Earth.

Question 18

Identify the three major types of plate boundaries

Answer 18

Divergent (spreading away from each other), Convergent (collision into or towards each other), Transform (sliding past each other)

Question 19

Describe the process of a Converging plate boundary

Answer 19

2 types- (1) if oceanic meets continental or (2) if continental meets continental
(1) Oceanic crust is denser than continental and therefore goes beneath continental when they meet (process known as subduction). This causes friction which produces heat and melts some of the rock making the continental crust. Volcanoes can form as a result of this. (2) when continents meet head on, the crust tend to buckle and pushed upwards or sideways. This forms mountains and sometimes earthquakes.

Question 20

Describe the process of Diverging plate boundary

Answer 20

spreading zones occur in oceanic crust where two plates are moving away from each other. Magma wells up in the mid-ocean ridge and forms new crust. Plates apart and new crust is created by magma pushing up from the mantle and solidifying.

Question 21

Describe the process of Transforming plate boundary

Answer 21

Crust is neither produced nor destroyed as the plates slide past each other. They get caught and when they suddenly break apart energy is released, Earthquakes result from this movement.

Question 22

What is an earthquake?

Answer 22

Vibration of the earth produced by the rapid release of energy.

Question 23

Identify the 3 main types of waves during an earthquake

Answer 23

P waves (primary), S waves (secondary) and L waves (Love)