The Structure of the Earth
Alfred Wegener (1920s) – idea of ‘’catastrophism’’
They were looking for ideas that God created certain
features
His papers weren’t well received
Wegener - Then came up with the ‘’gradualism’’
the idea that things happen slowly over time
e.g. south America + Africa – jigsaw theory
came up with theory of Pangea
Wegener wrote a book – ‘’The Thought of Continental Drift’’ but nobody believed
him because he didn’t have much evidence.
1940s – End of WW2
all empires knocked out, only 2 global superpowers left (USA and
Soviet Union (Russia))
start of cold war
Alaska was sold to the USA from Russia giving the USA an advantage to
threaten with nuclear weapons
1960s – US Navy employed geophysicists; Mckenzie + Hess
Used sonar imaging to map the bottom of the Atlantic Ocean
Produced accurate maps but over time they became inaccurate
Map changes caused questioning of continental drift because the
mountains have ‘’moved’’
They proved that Wegener was correct and therefore published ‘’The
Theory of Plate Tectonics’’
Proof of continental drift – Elephants
Elephants found in Africa, Madagascar and India are genetically identical
Because they were once all connected + when India meets Asia it creates the
Himalayan mountains.
How?
Mckenzie and Hess had access to radar beams that could be sent through the
earth to provide the theory.
gets cooler moving outwards away from the centre
Core – inner + outer = metallic (iron + nickel)
Asthenosphere (mantle) – liquid/solid – plasticity
Lithosphere (crust) – solid – hard magma
Core - radioactive decay = releases heat
Alfred Wegener (1920s) – idea of ‘’catastrophism’’
They were looking for ideas that God created certain
features
His papers weren’t well received
Wegener - Then came up with the ‘’gradualism’’
the idea that things happen slowly over time
e.g. south America + Africa – jigsaw theory
came up with theory of Pangea
Wegener wrote a book – ‘’The Thought of Continental Drift’’ but nobody believed
him because he didn’t have much evidence.
1940s – End of WW2
all empires knocked out, only 2 global superpowers left (USA and
Soviet Union (Russia))
start of cold war
Alaska was sold to the USA from Russia giving the USA an advantage to
threaten with nuclear weapons
1960s – US Navy employed geophysicists; Mckenzie + Hess
Used sonar imaging to map the bottom of the Atlantic Ocean
Produced accurate maps but over time they became inaccurate
Map changes caused questioning of continental drift because the
mountains have ‘’moved’’
They proved that Wegener was correct and therefore published ‘’The
Theory of Plate Tectonics’’
Proof of continental drift – Elephants
Elephants found in Africa, Madagascar and India are genetically identical
Because they were once all connected + when India meets Asia it creates the
Himalayan mountains.
How?
Mckenzie and Hess had access to radar beams that could be sent through the
earth to provide the theory.
gets cooler moving outwards away from the centre
Core – inner + outer = metallic (iron + nickel)
Asthenosphere (mantle) – liquid/solid – plasticity
Lithosphere (crust) – solid – hard magma
Core - radioactive decay = releases heat
