Ripple marks are small, wave-like patterns found on sedimentary rocks and surfaces, formed by the movement of water or wind over loose sediment. These marks indicate the direction of the flow and can provide valuable information about the environment in which the sediment was deposited. There are two main types of ripple marks: current ripples, created by flowing water, and wave ripples, formed by the action of waves. Studying these features helps geologists understand past environments, such as ancient rivers or shorelines, and can reveal insights into the Earth's geological history.