Origin of Life Flashcards
When was the earth formed?
at least 4.6 billion years ago
How do we know when the earth was formed?
radioactive emissions from meteorites found on the Earth and the Moon leads us to infer that the Earth formed at
least 4.6 billion years ago
What techniques study the structure of the earth?
Advanced techniques in analysing seismic
waves, the Earth’s magnetic field, and geomagnetic
and gravity measurements
Why are rocks important to scientists?
Rocks can be dated by both absolute and relative
techniques
Why do living organisms affect changes in the Earth?
taking in liquid water and releasing water vapour to the atmosphere. Aquatic living organisms also affect the levels of dissolved gases and the levels of dissolved solids.
How did the concept of plate tectonics form?
gradually built up over the years based on:
- complementary shape of parts of the present continents
- similarities in rock formations and plant species,
though much of the scientific community was initially
sceptical
What led to the acceptance of plate tectonics?
paleomagnetism, especially critical evidence concerning the magnetic orientation of rocks from either side of the
mid-Atlantic ridge
What is paleomagnetism?
the branch of geophysics concerned with the magnetism in rocks that was induced by the earth’s magnetic field at the time of their formation
How are tectonic plates observed?
As a result of new technologies to measure distance
and position very precisely
What is the Earth’s crust made of?
The Earth’s crust is comprised of a number of
separate plates that gradually move relative to each
other.
What has happened to tectonic plates over time?
Over geological time the number and shape of the
plates, as well as the positions of these, have
undergone many changes.
What do tectonic plates cause?
Interactions of the plates are responsible for
earthquakes and physical features such as volcanoes
and mountain ranges.
What surrounds the Earth?
The Earth is surrounded by an atmosphere, the
composition of which has changed and continues to
change
What causes the ozone layer?
Radiation from the Sun, especially UV light, causes
chemical reactions between components of the
atmosphere
What causes gases in water?
Equilibrium exists between gases in the atmosphere
and gases dissolved in water on the surface of the
Earth, which hence acts as a reservoir of gases
What has a detailed study of the atmosphere enabled us to do?
develop models that can predict the effects of
changes in gas composition that may occur in the
future