How long ago was the Earth was formed?
Approximately 4.6 billion years ago.
How were scientists able to reconstruct ideas on the Earths early atmosphere?
The discovery of gas bubbles trapped in ancient rocks and the data gathered from the atmosphere and other planets, moons and in the solar system.
What’s a poplar theory about the earths atmosphere.
Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans.
What was the Earths early atmosphere composed of?
CO2, Water Vapour, H2O, N2.
What’s the Earths atmosphere composed of NOW (and the composition)?
Nitrogen- 78%
Oxygen- 21%
Argon- 0.9%
Carbon dioxide- 0.04%
Trace amounts of other gasses.
Why is the evolution of the atmosphere only considered a theory?
Although it’s supported by lots of evidence, it did take over the past 4.6 billion years which means there is not as much evidence as we’d like.
What was the Earth itself like in the first billion years of its history?
Really dry and there was intense volcanic activity.
What did the intense volcanic activities produce?
Large amounts of- carbon dioxide, water vapour, and nitrogen.
Small amounts of- methane and ammonia.
What was the early atmosphere mostly composed of? Similar to which planet today?
Carbon dioxide, similarly to Mars and Venus today.
What happened to the water vapour produced by the volcanoes?
It condensed into liquid water and fell to the Earth to form the first oceans.
How were sediments in the sea bed formed?
Some (lots) carbon dioxide from the atmosphere would dissolve in the oceans, forming carbon precipitates that eventually became sediments in the sea bed.
What happened after algae began to appear and how long ago was it?
2.7 billion years ago algae appeared (the changes became more rapid as green plants evolved over the following billion years) and since they could photosynthesise they took in lots of the CO2 from the atmosphere and produced oxygen as a product.
Algae and green plants photosynthesise? How did that affect the atmosphere?
They took in carbon dioxide which lead carbon dioxide levels to decline and since they released oxygen as a product, oxygen levels started to build up.
What allowed the evolution of more complex life?
Photosynthesis of algae (and green plants) led to a decrease in CO2 levels and an increase in O2 levels which eventually allowed more complex life (e.g. animals) to evolve.
How were sedimentary rocks formed and what do they trap?
Algae and green plants could hold relatively small amounts of CO2 in their bodies. When they died they fell to the seabeds and became buried in layers of sediment. Over millions of years the sediment became compressed to form sedimentary rocks to trap the carbon.
Why did sedimentary rocks trap carbon?
To stop it from getting back into the atmosphere.
What are the (3) different types of sedimentary rocks made up of and the substances(what are the substances that aren’t rocks called)? What they depend on to form the different types?
The types substances fomed depended on the conditions involved a the type of organism burried.
Crude oil and natural gas- dead plankton mainly.
Coal- sedimentary rocks mainly from thick deposits of dead plant material.
Limestone- sedimentary rocky mainly made up of calcium carbonate that marine organisms incorporate into their shells and skeletons.
Why do we have large quantities of sedimentary rocks and fossil fuels in the ground?
Because lots of plants, algae and other organisms died and sunk to the bottom of the ocean. (Elaborate)
Name the steps of the evolution of the atmosphere in chronological order (8).
1)( 4500?) million years ago- volcanos released CO2, H2O and N2 into the Earths atmosphere.
2) The atmosphere was mostly CO2. N2 gradually built up and there were small proportions of methane and ammonia.
3) Water vapour condensed and fell to the Earth to form the first oceans.
4) Around 3.4 billion years ago the first life started on Earth but the organisms didn’t need oxygen.
5) Around 2.7 billion years ago algae formed and began to photosynthesise, releasing oxygen as a waste product.
6) Oxygen levels increased. Plants and animals began to evolve.
7) Levels of CO2 dropped. Carbon became trapped.
8) Currently the Earths atmosphere is mostly nitrogen and oxygen.
What’s a greenhouse gas?
A gas that contributes to the greenhouse effect by absorbing infrared radiation.
Sources of greenhouse gases?
CO2=
- Combustion.
CH4=
- Swamps.
-Paddy fields (where rice is grown).
-Animals (especially grazing cattle).
-Rubbish dumps.
Define global warming.
The increase in the average temperature of the Earths atmosphere.
Define carbon footprint.
The total amount of CO2 and greenhouse gases emitted over the full lifecycle of a product.
What is the atmosphere and what is it for?
A protective layer of gasses that acts as an insulating layer or like a greenhouse to keep in the perfect amount of the suns heat energy, so the Earth stays at an optimum temperature all the time.
