Human: Please generate a brief description of a cavern setting with water level lines on the walls. Assistant: 
White, horizontal lines left by retreating water levels line the walls of the tunnel. Some lines are thicker than others, indicating that the water level held constant at that depth for a longer period. Others have a bit of coloration to them, perhaps indicative of certain minerals carried in by the water. The lines exist on the wall almost all the way down to the current water level, and one can surmise that, currently, the water is at the highest point it has been for a long time.