MesoGaian Type

If a young planet, having passed through an EoGaian stage of existence, maintains a fair amount of geological activity and a substantial atmosphere, it is probable that it will evolve into the MesoGaian Type world.  These worlds have a somewhat more advanced form of atmosphere, with greater amounts of carbon dioxide and nitrogen, often times thickly enshrouded with methane as well.  Because of this, the surfaces are almost always totally obscured by global cloud cover.

In age, these worlds range from 800 million to 2.3 billion years old, with room for some variance.  It is during this time that the planet's geology also begins to mature.  With the presence of often large oceans, plate tectonics initiate and a system of erosion and mountain building is begun.  This process is very important in removing carbon dioxide from the atmosphere and locking it within the rocks, while more is released into the atmosphere through volcanism.  The only real block towards turning the atmosphere into an oxygen rich form is the absence of life.

Life does indeed tend to occur on these worlds.  Indeed, it is almost inevitable.  But atmospheric and geological conditions make it almost impossible for any other form other than microscopic monocellular microbes.  Even though these worlds still suffer through frequent, major collisions from asteroids, these events are spaced far enough apart as to give life a chance to proliferate.  The seas, particularly along heavily churned coastlines, are absolutely rife with life.

The future development of these worlds can be quite varied.  If plate tectonics fail to initiate fully, or if the planet is too close to its steadily brightening sun, then the surface water can be lost and a massive greenhouse effect can form, creating a Cytherean world.  If the world is not massive enough to retain an active geology or a substantial atmosphere for a geologically significant period of time, the again the oceans can disappear, most often freezing out beneath the surface, and an Arean world can develop.  Many other fates can occur as well, including the further development into an ArchaeoGaian Type world -- the next step in planetary evolution leading to a true Gaian world.

From space, MesoGaian worlds look much like Cytherean planets, in that they are enshrouded within a thick atmosphere.

The brown to golden, cloud laden skies of a MesoGaian world are rich with carbon dioxide and methane.

Quick Facts

The Uses of MesoGaian Worlds: Despite their appearances, MesoGaian worlds are quite suitable for Human habitation, being rich with the raw materials needed not only for habitat construction, but with the elements needed for successful terraforming.


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ArcBuilder Universe concept John M. and Margo L. Dollan 2002-2004
This Page first uploaded June 13, 2004
Most recent update for this page June 15, 2004