Explain the origin of (a) bedding, (b) cross-bedding, (c) graded bedding, and (d) mud cracks.

In summary, the origins of the four geological features are as follows: (a) Bedding forms when sediments accumulate in horizontal layers in various geological environments, eventually compacting and cementing together to form sedimentary rocks with visible bedding planes. (b) Cross-bedding occurs when sediment is transported and deposited by moving water or wind, creating inclined layers within horizontal layers of sedimentary rock. (c) Graded bedding forms due to the settling of sediment particles in water, with larger and coarser particles settling first, followed by progressively smaller and finer particles, creating a vertical gradation in particle size. (d) Mud cracks result from the drying and shrinking of fine-grained sediment, such as clay or mud, forming a network of polygonal cracks on the dried sediment layer's surface, typically found in environments with fluctuating water levels.