The Earth In The Universe

Front 1

estimations of earths age

Back 1

4500 million

Front 2

mountain formation

Back 2

if new mountains weren't being formed the earth's surface would have eroded down to sea level.

Front 3

Wegener’s theory

Back 3

Alfred Wegener proposed the theory of continental drift.
-the same types of fossilised animals and plants are found in South America and Africa
the shape of the east coast of South America fits the west coast of Africa, like pieces in a jigsaw puzzle
matching rock formations and mountain chains are found in South America and Africa.

Front 4

Inside the Earth

Back 4

-The crust, which is relatively thin and rocky
-The mantle, shown here as dark red, which has the properties of a solid, but can flow very slowly
-The outer core, shown as orange, which is made from liquid nickel and iron
-The inner core, shown as yellow, which is made from solid nickel and iron

Front 5

Movement of tectonic plates

Back 5

volcanoes, mountains and earthquakes occur at the edges of tectonic plates - their creation depends on the direction the plates are moving.

Front 6

Volcanoes

Back 6

If the plates are moving apart, as at mid-ocean ridges, volcanoes are produced as molten magma is allowed to escape. This happens in Iceland.

Front 7

Mountains

Back 7

If the plates are moving towards each other, the edges of the plates crumple, and one plate ‘dives’ under the other. This is called subduction. It produces mountains, like the Himalayas. The friction of the movement can also melt rocks and produce volcanoes.

Front 8

Earthquakes

Back 8

if the plates are moving sideways, stresses build up at the plate boundary. When the stress reaches some critical value, the plates slip suddenly, causing an earthquake.

Front 9

geohazards

Back 9

natural hazard

Front 10

P and S waves

Back 10

Vibrations from an earthquake are categorised as P or S waves. They travel through the Earth in different ways and at different speeds. They can be detected and analysed.

Front 11

p-waves

Back 11

P-waves (P stands for primary) arrive at the detector first. They are longitudinal waves which mean the vibrations are along the same direction as the direction of travel.

Front 12

S-waves

Back 12

S-waves (S stands for secondary) arrive at the detector of a seismometer second. They are transverse waves which mean the vibrations are at right angles to the direction of travel.

Front 13

Amplitude

Back 13

It is the distance from the middle to the top.

Front 14

Wavelength

Back 14

is the distance between a point on one wave and the same point on the next wave.

Front 15

Frequency

Back 15

The frequency of a wave is the number of waves produced by a source each second.

Front 16

Wave speed

Back 16

Wave speed is the velocity at which each wave crest moves and is measured in metres per second (m/s).

Front 17

asteroids

Back 17

small rocky masses that orbit the sun

Front 18

moons

Back 18

small masses that orbit the planets

Front 19

comets

Back 19

small icy masses that orbit the sun

Front 20

Light-years

Back 20

A light-year is the distance light travels in a year. light travels very fast (300,000 km/186,282 miles per second), and takes only about eight minutes to reach us from the Sun.

Front 21

parallax

Back 21

the closer the are the more they appear to move. the further the star the less accurate the measurement is.

Front 22

edwin hubbles law

Back 22

the speed at which a galaxy is moving is proportional to its distance from us.

Front 23

big bang theory

Back 23

theory says that the universe began with a explosion 14000 million years ago.

Front 24

tectonic plates

Back 24

earth crust cracked in several large pieces