Introduction Lecture 1 - The Earth System

Question 1

Summarise the Stone Age

Answer 1

-Lasted 3.4 million years
-Humans learned how to use stones
-Facilitated hunting and other tasks

Question 2

Summarise the Bronze Age

Answer 2

-Started around 6000-3000BC
-Humans learned how to extract metal from rocks (copper and tin to make bronze)

Question 3

Summarise the Iron Age

Answer 3

-Started around 1200BC
-Humans start extracting iron to make steel tools
-Ended around 200BC-100AD

Question 4

Summarise the Industrial Age

Answer 4

-Lasted from 1760-1970
-Fueled by coal mining which allowed us to harness steam energy; power tools and running water
-Population increased but so too did pollution
-This began anthropogenic climate change

Question 5

Summarise the Oil Age

Answer 5

-1901-present
-Oil extraction to fuel economy; the world is now dependent on oil

Question 6

Summarise the Space Age

Answer 6

-1957-present
-Lunar and potentially Martian exploration
-Satellite data is a huge industry and critical for resource management and mitigation/ planning of natural disasters

Question 7

Summarise the Information Age

Answer 7

-1970-present
-Extraction of rare earths for computers and new technology
-Economy driven by IT
-The rise of AI and machine learning

Question 8

Summarise the Big Bang

Answer 8

-First atoms (protons and neutrons formed in the first second)
-Hydrogen, helium and small amounts of lithium and berillium are formed

Question 9

Summarise the first Star Formation

Answer 9

-Gasses come together under gravity
-Heat and pressure fuses hydrogen atoms to create helium (nuclear fusion)
-This fusion produces heavier elements all the way up to iron

Question 10

Summarise the first Star Deaths

Answer 10

-Some stars go supernova and produce the rest of the elements in the periodic table
-Some of these heavier elements allow planet building and therefore life

Question 11

Summarise the Formation of the Earth

Answer 11

-Asteroids and protoplanets collide to form a primitive Earth
-Asteroid impacts, planet formation and radioactive elements provide heat
-Planetary differentiation occurs
-Water is brought to Earth by asteroids and condenses due to Earth’s position inside the habitable zone

Question 12

Explain Planetary Differentiation

Answer 12

-Heavier metals like iron and nickel sink to form the Earth’s core
-Lighter elements rise upwards, cool and condense to form the Earth’s crust

Question 13

Explain how we obtained knowledge of the Earth’s interior

Answer 13

-Seisimic body waves (P and S) can travel through liquids (P waves also through solids)
-Changes in density cause the waves to refract
-Density increases with depth in the Earth

Question 14

Outline the main layers of the Earth

Answer 14

-Crust
-Mohorovicic Discontinuity
-Lithosphere
-Asthenosphere
-Transition Zone
-Core (Outer and Inner)

Question 15

Describe the Crust

Answer 15

-Outermost layer of the solid Earth
-Oceanic crust is basaltic, 1-10km thick
-Continental crust is granitic, 30-80km thick

Question 16

Describe the Mohorovicic Discontinuity

Answer 16

-The boundary between the crust and mantle

Question 17

Describe the Lithosphere

Answer 17

-This contains the crust and the rigid upper mantle

Question 18

Describe the Asthenosphere

Answer 18

-Plastic (able to be molded and shaped)
-This is below the lithosphere

Question 19

Describe the Transition Zone

Answer 19

-The boundary between the upper and lower mantle, around 660km deep
-Here, seismic waves change direction

Question 20

Describe the Core (Inner and Outer)

Answer 20

Outer: -Liquid
-2900-5100km deep
-Earth rotation and
convection currents here
create the Earth’s magnetic
field

Inner: -Solid
-5100-6371km deep
-Single massive crystal of
iron and nickel

Question 21

What is meant by Uniformitarianism?

Answer 21

-Natural laws and processes remain constant across space and time

Question 22

Summarise the Rock Cycle

Answer 22

-Sediments come together through compaction and cementation to from sedimentary rocks
-Sedimentary rocks become metamorphic when exposed to heat and pressure
-Metamorphic rocks are melted into magma, and then condense to form igneous rocks
-Over time, igneous, metamorphic and sedimentary rocks are broken down, through weathering and erosion, to form sediments once more