The displacement of memory

What does "the displacement of memory" mean in the following context? Does it mean "the fact that we carry memories with ourselves and can remember them whenever we want"?

Context:

Magdalena, 1992, is comprised of six polaroids and two engraved plastic plaques. The pairs of images on the left-hand side and on the right-hand side both display a white shoe box, the plaque under the left-hand pair reading ‘at her burial I stood under the tree next to her grave’. The middle pair of photographs display a pair of women’s shoes, in one image facing forwards, in the other turned away from the viewer, while the plaque under the right-hand pair of white shoe boxes reads ‘when I returned the tree was a distance from her marker’. What is imaged here is not only the temporal displacement of memory in relation to the seeming stasis of photographic representation, but the absent body that can only be invoked in the face of its disappearance in death. Magdalena represents both a particular narrative, the loss of a parent and their history, and a universal narrative, the gaps in knowledge generated by the encounter with mortality. The displacement of memory formalised by the text on the plaques in Simpson’s Magdalena signifies an absence at the heart of the work that mirrors the impossibility of experiencing our own death. Although we are certain we will die, we cannot have ‘knowledge’ of this experience. While our desire for knowledge remains thwarted, our unconscious drives impel us to return again and again to this subjective end point (Art and Psychoanalysis by Maria Walsh).