When the Votans set out for Earth, they sought a planet they could remake into the image of their own homeworlds. Terraforming (the word borrowed from English) is the process of converting a section of a planet for Votan habitation. This includes everything from reshaping the landscape to introducing entirely new species of alien plant and animal life. However, when the Votans realized Earth was inhabited, they put their plans on hold. When the Arks mysteriously exploded, the terraforming equipment ran rampant, creating an unplanned hybrid landscape that is neither fully human nor alien. 
The terraformation devices follow a precise protocol. The terraspires are dropped from the ark on orbit to their place of action. Then they position themselves at the top of their target by flying, and disperse 2 types of terraspheres. One will keep flying and irradiate the area with an energy beam, thereby modifying the geological structure of the terrain and sterilising the area of native lifeforms. The other falls to the ground, explodes and releases DNA to create a more Votan-like environment. The terraformation process follows a precise grid.
Unfortunately when the ark fell, the terraformation systems activated themselves incorrectly, unintentionally modifying the topography and the environment in the wrong way, combining DNA of different species and artificially accelerating the evolution of others, and so creating new species in a totally reshaped ecosystem.
However terraforming has been use correctly on earth at least two time, on sulos colony whith the agreement of the UN votan had perfectly recreated irathian meadows, sensoth forest, daribo's deserts etc... (they invited the peoples who lived here to watche these marvellous) and on new york (probably all columbia) and belize by the kaziri in his attempt to create a wulaiche.