Summary of the
The nature of the Universe and the Earth
are examined in this chapter. The Big Bang theory is
presented as a model to explain the origin, history,
and future of the Universe. Most cosmologists and physicists
believe matter, energy, space, and time in our Universe
were created from a huge explosion about 15 billion
years ago. Ever since this explosion the Universe has
been expanding at the speed of light. About 5 billion
years ago our solar system formed. Verification of
the Big Bang theory is based on four pieces of evidence.
The formation and evolution of the Earth
is then explored next. The Earth began forming about
4.6 billion years ago. The timing and development of
the Earth's continents and the atmosphere is discussed.
It is then suggested that the Earth can be seen to
be composed of four principal components: lithosphere,
biosphere, atmosphere, and hydrosphere. It is also
suggested that linkages exist between the components
through biogeochemical cycling.
The topic concludes
with an examination of the Gaia hypothesis. This
theory suggests that life has the ability to control
and modify certain aspects of the Earths lithosphere,
atmosphere and hydrosphere. This modification is
done when one of these components is change in a
way that is detrimental to living organisms. Life
can respond and reverse the changes to the environment
through growth to attain the optimum conditions for
List of Key Terms
Abiotic, Angiosperm, Atmosphere, Average
Cycling, Biosphere, Biotic,
Hypothesis, Glacier, Greenhouse
Effect, Groundwater, Groundwater
Hydrologic Cycle, Hydrosphere,
Igneous, Infiltration, Inorganic,
Lithosphere, Lake, J.E.
Magma, Metamorphic, Methane, Mineral,
Ocean, Organic, Organic
Photo-Dissociation, Photosynthesis, Precipitation,
River, Rock, Runoff,
Sedimentary, Snowfield, Sublimation,
Problems, and Exercises
(1). Give a brief account of the formation
of the Earth since its beginnings 4.6 billion years
ago, noting important stages in its formation.
(2). Explain the origin, history and
future of the Universe.
(3). What is the Gaia hypothesis? Is
there any evidence for this theory?
(4). Define the following: lithosphere,
hydrosphere, biosphere and atmosphere. How are they
related to each other?
(5). Using the hydrological cycle as
an example, show how the four spheres of the Earth
are connected and interrelated.