Final answer:
Cross-bedding is an angular or dipping sedimentary structure within planar strata, informing geologists of the direction of ancient sediment transport.
Step-by-step explanation:
An angular or dipping sedimentary structure contained within an overall planar strata is an example of cross-bedding. This phenomenon occurs when groups of inclined layers, known as cross strata, form on sloping surfaces such as ripple marks and dunes due to the movement of water or wind. Cross-bedding is distinctive because it indicates the direction of sediment transport based on the orientation of the steep sides of the ripples or dunes, which angle downward toward the direction the medium (water or wind) was moving.
Other sedimentary structures include graded bedding, which showcases a variation in particle size from coarser at the bottom to finer at the top of the bed, usually formed by a decrease in transport energy or by turbidity currents. Ripple marks are another sedimentary structure seen as a wavy pattern on sediment surfaces. Each of these structures helps geologists interpret the history of Earth's geological environment.