Claiming the River Stone

I rolled out from the shelter of the woodpile to survey the morning grounds. The dirt path was damp and hard under my weight. In the middle of the track lay a heavy, smooth river pebble, coated in thin grey silt. It tried to hold its position. I hit it with my side, ramming it three inches across the gravel until it hit the mossy border. Now it marks the outer line of my territory. Nothing stays where it wants when I decide to advance.