Transcript The changing Earth

P1 – the earth and the
universe
There are some really dull things in the solar
system, for example, asteroids don't do much
except rotate around the sun and they can also
be very dangerous etc if one was to come
crashing to earth that would be the end of life
full stop. However earth is different it
possesses something that all the other planets
and things in our solar system do not and that
would be oxygen and life.
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Its kind of tempting to think that the earth is a
steady, unchanging place that will always look
as pretty much as it does now.
But no... In a few tens of millions of years,
Earth is going to look alot different
Mountings that are enormous today wont be
nearly so grand, and the map of the world will
be very different – whole continents would
have moved
This is nothing new – earths been changing for
thousands of millions of years
Rocks change over the years – so the surface of the earth hasn’t
always looked the way it does now.
1.
Look at the grand canyon, for example. Over time, the
Colorado river has eroded the rock, leaving and impressive
slash through the middle of Arizona .
2.
Erosion goes on everywhere. We see it happening, for example,
when the cliffs are worn away from the sea. But other processes
must be happening as well. If not, all the high ground would
have been worn down by now... Earth would be perfectly
smooth.
3.
So some process must be making new mountains. And
evidence is pretty easy to find – E.g when lava from volcanoes
set it forms brand new rock.
4.
There are also some spectacular forces at work in the earth,
which can push up old rock to make new mountains – some
rock formations show rock that has been squeezed so hard its
just folded.
More evidence that rock is forming comes from
fossils. The animals and plants couldn't have
dug themselves into the middle of rocks – the
rocks must of formed around them. This type
of rock is made by sedimentation – particles
eroded from existing rock get washed to the sea
and settle as sediment. Over time, these
sediments get crushed together to make new
All therock.
rock processes that we can see happening now – E.g erosion, sedimentation,
5.
volcanic activity, etc. Will have been going on for millions of years. Geologists can
use that fact to explain how various modern landscapes were formed
1.
2.
By looking at the proportions of radioactive
potassium-40, and the element it decays into, in
certain rocks, scientists can get a good idea of
when the rocks were formed. (its tricky but it
can be done)
Scientists can use this to help estimate the age
of the planet – the earth must have been around
at least as long as the oldest rocks.
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