Our Changing Planet Flashcards
(34 cards)
On the surface of tr earth there is a crust hat is what?
Thin&solid - very thin layer that varies in think ness between 5km and 70 km
What’s the earths diameter
12800km
What’s under the crust and how think is it?
The mantle and 3000km - it goes half way to the centre of the earth land is almost intently solid but parts of it can flow very slowley
The core
Half the diameter of the earth. High proportion of the magnetic metals iron and nickel has a liquid outer part and a soils inner part
The atmosphere
Most of air is within 19km of the surface and atmosphere is 100km of the surface
All raw materials that we depend on come from where?
The crust, oceans and the atmosphere (meaning they are limited)
The earths layers in order
Atmosphere, crust, mantle, outer core, inner core
What are tectonic plates believed to be? Why so they do this?
The crust and upper part of the mantle have broken into these plates and move a few centre meters a year because of convection currents In the mantle Beneath them.
What are convection currents in the lower mantle caused by?
By energy being realised by decay of radioactive elements heating up the mantle
How build up where plates meet and what does this cause?
Huge forces. Earthquake and sudden movement volcanos and mountains
Why can scientists predict when earthquakes will happen?
We don’t know enough about what’s happening in the earth - we can’t make accurate predictions
What causes tectonic plates to move?
Convection currents caused by Heston of the mantle inside the earth from radioactivity an the decay of radioactive elements
Who came up with the theory of continental drift? Why was theirs idea not accepted for years?
Alfred wegener - because he couldn’t explain why continents moved. They though in 1915 that the earth was shrinking as it cooled
When was the earth believed to be formed - what did they believe happened in the first billion years
4.5 billion years ago - fist billon years the earth was covered with volcanos that released cabin dioxide and water vapour and nitrogen
What happened to the water vapour
Believed to have cooled to form oceans
What did scientist believe that atmosphere was made from
Carbon dioxide, little water vapour - nitrogen as some maths me and ammonia
What evolved I the next two billion years
Bacteria, algae and plants which used co2 for photosynthesis and released oxygen
What did plants that produce oxygen evolve from?
Organisms like plankton and algae in ancient oceans
Why don’t we know how molecules of the simplest living things were formed
Insufficient evidence
What’s the miller and urey experiment - 1952
Use a mixture of water, ammonia, methane and hydrogen and a high voltage spark to stimulate lighting (they believe this was in wary life’s atmosphere) - they found amino acids the building blocks for proteins had been produced
What’s primordial soup?
That amino acids in this mixture combined to make proteins from which life began
Where did carbon that was taken in from plants end up? What did this mean?
In plant and animals remains as sedimentary rocks and fossil fuels
What was limestone formed from?
The shells and skeletons o mar none organisms
What do foul fuels contain?
Carbon and hydrogen from plants and animals
