How the rock got there isn't important. It was an igneous rock, if knowing that makes you feel better about things. It was a large rock, as rocks go... some people called it a bolder, but the rock made no fuss about labels. As rocks are wont to do, the rock sat in one place for a long time.
Under the rock was a seed. As water dripped from the sky, and fell on the rock, it percolated down, into the soil, and the seed grew. It sent up feelers, looking for light, and it found a crack in the rock. It grew some more. Each time that it grew, it pushed the rock a little, and the crack got bigger. Eventually, the seed grew into a tree, and the crack grew quite large.
In time, the tree died. It fell to the ground, and over time, it decomposed. But the rock remained. The rock retained the crack. In its own way, and in its own time, the rock remembered the tree.