Spaces between.
In anthropology, liminality (from the Latin word līmen, meaning "a threshold") is the quality of ambiguity or disorientation that occurs in the middle stage of a rite of passage, when participants no longer hold their pre-ritual status but have not yet begun the transition to the status they will hold when the rite is complete. During a rite's liminal stage, participants "stand at the threshold" between their previous way of structuring their identity, time, or community, and a new way (which completing the rite establishes). wikipedia 
An ecotone is a region where two ecological systems overlap. In that overlap, there is a tension. The word is derived from "ecology", in English, and "tonos", meaning tension, in Greek.