Oxbow reality

An oxbow reality (also referred to as oxbow timelines and oxbow worlds) was a type of reality created as a side effect of discontinuities caused by the rewriting of time; with enough rewriting, these sequences could be slowly detached from the main body of causality. (PROSE: Weapons Grade Snake Oil)

The Eighth Doctor once proved to Sabbath Dei that the universe only split into parallel universes after major decisions and that minor decisions with little effect on history — such as choosing one newspaper over another — only caused the universe to naturally loop within itself then coalesce into a single path, leaving behind "oxbow lakes of might-have-been". (PROSE: Time Zero)

Oxbow timelines were one way for things or people like Hauserkinder to survive the erasure of timelines. The Great Houses and Faction Paradox held that the Mal'akh were the result of oxbow-style aberrations in time. (PROSE: The Book of the War)

If a person was trapped in an oxbow, depending on their levels of narcissism, they could be left completely unaware of their separation, enjoying their own, personal, heroic victory. Some thinkers believed that War in Heaven could spontaneously resolve itself if its most narcissistic participants were quarantined in this way. Godfather Morlock wrote an entry on oxbow realities for The Book of the Truce. (PROSE: Weapons Grade Snake Oil)

The Sanctum of the Heretic was an oxbow world/oxbow timeline. (PROSE: Resurrection of the Author)