Pages in this set

Page 1

Preview of page 1
4/6/12 12:05 PM




The Earth is divided into four main layers, the crust, the mantle, the outer core and
the inner core.

Crust: The crust is solid and is the layer we live on. The crust is usually between
10km and 60km thick. The crust thickness is often referred to…

Page 2

Preview of page 2
4/6/12 12:05 PM



down. As the cooled material sinks down, it is warmed and rises again.
Scientists once thought that Earth's plates just surfed on top of the mantle's
giant convection cells, but now scientists believe that plates help themselves
move instead of just surfing along. Just like convection cells,…

Page 3

Preview of page 3
4/6/12 12:05 PM




The plate tectonics theory dates back to the early 1600s. It is a scientific
theory which describes the large scale motions of Earth's lithosphere. The theory
has developed over time from the questioned theories of continental drift to
form the plate tectonics theory, more widely accepted by…

Page 4

Preview of page 4
4/6/12 12:05 PM




Volcanic & Seismic events are pieces of evidence proving that the plate
tectonics theory is valid

describe the distribution of volcanoes around areas such as the Pacific
ring of fire and explained how without movement at the boundaries
around the Pacific, volcanoes such as Mt St Helens…

Page 5

Preview of page 5
4/6/12 12:05 PM



causing shockwaves to rip through the surrounding area, an example
of this is the 1995 earthquake in Kobe, Japan where the plate
slipped over 1m. Earthquakes are also common however at
conservative margins, where plates slip past each other and the build
up of friction can cause…

Page 6

Preview of page 6
4/6/12 12:05 PM




Wegener ­ The Origins of Continents and the Oceans
Alfred Wegener was the scientist who championed the Continental Drift Theory
through the first few decades of the twentieth century. Simply put, his
hypothesis proposed that the continents had once been joined, and over time
had drifted apart.…

Page 7

Preview of page 7
4/6/12 12:05 PM




o "If we are to believe in Wegener's hypothesis we must
forget everything which has been learned in the past 70
years and start all over again." He was right.
After Alfred Wegener died, the Continental Drift Theory was
quietly swept under the rug. With the Continental…

Page 8

Preview of page 8
4/6/12 12:05 PM



(normal) polarity. 3. Stripes of rock parallel to the ridge crest
alternated in magnetic polarity (normal, reversed, normal. Etc.),
suggesting that the magnetic striping and the construction of the
id-oceanic ridge system, the sea floor spreading hypothesis gained
converts and represented another major piece of evidence towards…

Page 9

Preview of page 9
4/6/12 12:05 PM




Tectonic plates are powered by convection currents, which is the
circular movement of magma within the mantle. These currents are
powered by the core, which heats the magma, causing it to rise, cool
and fall back down. This circular motion causes the plates, which float
on the…

Page 10

Preview of page 10
4/6/12 12:05 PM



plate margins, shallow focus earthquakes occur over a broad zone, for
example Sichuan, China 2008.
WAVES
Different materials transmit and reflect seismic shock waves in different
ways, and of particular importance to the theory of plate tectonics is
the fact that liquid does not transmit S-wave. Because…

Comments

tom dixon


This is really good thank you!

 

Similar Geography resources:

See all Geography resources »See all resources »