You could either denote the dimension as a spacial dimension......and there you would have a world as an instantaneous flash that exists for an infinitessimal amount of time, or you could denote the dimension as a temporal dimension, where absolutely nothing exists forever. Either way, you cannot have a concept such as a black hole materialize in one dimension. It makes no sence whatsoever. But a two-dimensional world may have a spacial and temporal dimension. In this, maybe a black hole could arise. This of course not being realistic but merely imagination, the black hole would appear as a stretched inversly parabolic cone (I don't know the topological term) that seems to dip down into the third dimension. Possibly infinite in length. Step this concept up one more dimension (actualy a couple of dimensions in our universe....3 space, 1 time dimension) and you have a real black hole.