The Fourth Element

The Encyclopedia of Earth is a new electronic reference about the Earth, its natural environments, and their interaction with society. The Encyclopedia is a free, fully searchable collection of articles written by scholars, professionals, educators, and experts who collaborate and review each other's work. The articles are written in non-technical language and will be useful to students, educators, scholars, professionals, as well as to the general public. The scope of the Encyclopedia includes; The hydrosphere, lithosphere, atmosphere, magnetosphere, cryosphere, and biosphere, and their interactions, especially in regards to how these systems support life and underpin human existence and the living organisms on Earth that constitute its biological diversity.