Changes in the Earth and its atmosphere Flashcards
The Earth consists of what layers?
The core, the mantle and the crust. This is surrounded by the atmosphere.
The Earth’s crust and upper part of the Mantle are cracked into…
…the tectonic plates.
Explain why the tectonic plates move.
Radioactive decay in the Earth’s core causes heat to be released. This heats the semi molten mantle and causes convection currents to form. As the magma in the mantle moves in the currents it drags parts of the crust with it, causing plates to move at relative speeds of a few centimetres per year.
Movements in the mantle can be sudden as pressure its released, causing what events to occur?
Earthquakes and/or volcanic eruptions on plate boundaries.
Composition of the Earth’s atmosphere (%).
80% Nitrogen
20% Oxygen
Small proportions of other gases.
During the first billion years there was intense volcanic activity…
…which caused the release of gases and water vapour that condensed to form the oceans.
There are many theories as to how the atmosphere was formed. One of these suggests that…
…it was mainly CO2 with small proportions of oxygen, water vapour, methane and ammonia.
How many theories are there of how life formed?
There are many theories as to how life was formed billions of years ago.
Describe the Miller-Urey experiment.
Miller and Urey made a mixture known as a primordial soup containing substances which they thought were in the early atmosphere such as CO2, ammonia and hydrocarbons. With an electrical current (acting as lightning) amino acids were formed, which are the building blocks of proteins and life.
How is there oxygen in the atmosphere now?
Plants and algae used photosynthesis which caused the carbon dioxide i the atmosphere to be used and oxygen to be produced as a product.
Most of the carbon from the carbon dioxide became locked up in what?
Sedimentary rocks as carbonates and fossil fuels.
How did carbon become locked up in rocks and fossils?
Carbon dioxide dissolve in oceans and limestone was formed from the shells and skeletons of marine organisms. Fossil fuels contain carbon and hydrocarbon which are the remains of plants and animals.
Increasing amounts of carbon dioxide absorbed by the oceans…
…has had an impact upon the marine environment.
Nowadays the carbon dioxide that is released by the burning of fossil fuels ends up where?
In the atmosphere.
True or False. Air is a mixture of gases with different boiling points, so can be fractionally distilled to provide raw materials for a variety of industrial processes.
True.
