A time fissure was a weakness in the fabric of time and space.
Places that were reputed to be haunted usually had a time fissure nearby. They were also often responsible for disappearances, as people accidentally wandered through them and got lost in time. Growing up near a time fissure tended to enable one to develop psychic powers such as precognition and "second sight". (DW: Image of the Fendahl)
The English village of Fetchborough was situated in or near a time fissure. Consequently and because of her long exposure to the fissure, a local, Martha Tyler had a reputation as a witch. The presence of the fissure made Fendleman's 1970s experiments with "Eustace", the skull of a Fendahl Core, even more dangerous. (DW: Image of the Fendahl)
In the late 2000s, Sarah Jane and her team examined a time fissure seven miles from the former site of Foxgrove, a village which no longer existed. She used a device to open and close the fissure. When activated, the fissure manifested as an glowing portal through which people could pass. It seemed that the Trickster had created this fissure deliberately as part of a trap set for Sarah. (SJA: The Temptation of Sarah Jane Smith)