Quote from previous link, in answer to a similar question comparing CAs (1d) to Conway's Life (2d): "The pictures you're looking at, one of the axes is time. O

Quote from previous link, in answer to a similar question comparing CAs (1d) to Conway's Life (2d): "The pictures you're looking at, one of the axes is time. One row "becomes" the row below it. Each time-step iteration adds a row to the bottom, while the rows above it are immutable (because they are in the past)."