Geology Reference
In-Depth Information
with the relative mass proportions of each sphere has been presented. This overview
has given way to a more detailed explanation of the geochemistry of the atmosphere,
hydrosphere and upper continental crust.
The atmosphere is the gaseous layer surrounding the Earth. The troposphere is
the lowest atmospheric layer and it is here where human beings interact the most.
The chemical composition of the atmosphere is rather uniform up to heights of 100
km. Apart from the naturally occurring gases, there are traces of anthropogenic
substances in the atmosphere that are thought to alter, or have at least some influ-
ence over the present conditions on Earth.
The hydrosphere is the liquid water component of the Earth and includes sea-
water (which constitutes over 97% of it); renewable water resources (rivers, lakes
and groundwater); ice; and atmospheric water vapour. Renewable water resources
as the main sources of freshwater, are essential for life on Earth. As opposed to
seawater, no uniform composition can be applied but some examples and averages
have been provided. Glaciers, ice sheets and ice caps have also been evaluated.
The solid Earth meanwhile is composed by the core, mantle and crust. The
crust is further divided into the lower, middle and upper part. The latter is the
reservoir of the main minerals and other natural resources the planet provides for
mankind. Being the most accessible it has been subjected to the greatest level of
investigation. Its chemical composition in terms of elements is well known. How-
ever, its mineralogical composition has been only superficially looked at and the
literature surrounding this topic until very recently was extremely limited and in-
accurate. Nevertheless, one single author, the Russian geochemist Grigor'ev has
single handedly provided the most comprehensive mineralogical composition of the
upper crust. His work is the basis of the exergy calculations and analysis developed
by the authors in Chap. 10.
To obtain a complete picture of the natural wealth on Earth it is now necessary to
provide an inventory of the principal energy and mineral resources as accomplished
in the following chapter.
Search WWH ::
Custom Search