P1 – Earth and the Universe
Except not the Universe
You do this in P7 in more detail
What can you say about this rock?
What can you say about this rock?
• At different times there were different materials around to make the rock.
– You can tell this because of the rocks colour
• If there were any fossils in the rock, you can age it and see what was in the atmosphere at that time
Understand Wegener’s theory of continental drift and his evidence for it
• Wegener was a meteorologist (studies the weather) he came up with the theory of continental drift. • His theory states that all land was originally joined together and has moved apart over time.
• What was his evidence for this? What was his evidence for this? • Fossils matching
• Identical rock layers
Why didn’t people believe him? What were their ideas?
• Land bridges
• Geologists didn’t believe a meteorologist
• No direct evidence (they move too slowly)
• They didn’t have evidence and he did.
Seafloor Spreading
• In the middle of the Atlantic ocean there is a ridge.
• This is creating ocean floor and pushing the land away, moving the continents. • We now can use this as further evidence of Weigner’s theory.
• But what feature always us to track this natural phenomenon.
Seafloor spreading proof
• The Earth has a metalic core which gives it a magnetic field. Every few thousand year this reverses.
• This causes the element crystals in the cooling rock to align themselves to the magnetic field. • We can see this is evidence on both sides of the ridge.
Destructive boundary
Earthquakes
• Destructive plate boundaries cause earthquakes
• Earthquakes have two types of waves:
– P‐waves (Longitudinal) Travels through solids and liquids
– S‐waves(Transverse) Travels only through solids
• This is how we know that the centre of the earth is a liquid as S‐waves cannot travel through it
Transverse Waves
Longitudinal Wave
• Both the particles and the wave moves in the same plane
Waves
Wavespeed = Frequancy x Wavelength
v = fλ
m/s = Hz x m
• Frequency is the number of waves passing a point each second
• Wavelength is the distance between the same point on the next wave
• Amplitude is the distance between a particles current position and its rest location
Earth Section