Final answer:
Sediment size and shape change due to weathering, transport energy, and sediment sorting processes.
Step-by-step explanation:
How Sediments Change During Transport
Sediment changes in size and shape due to mechanical and chemical weathering, as well as the energy of transport mechanisms like water, wind, and gravity. As a river flows away from its source, the current slows down due to decreased gradient and increased channel width from tributary input, leading to more sedimentation. This process sorts the sediment, with well-sorted sediment typically being far-travelled and consisting of grains of similar size. Mechanisms such as graded bedding indicate a decrease in transport energy over time, with coarser particles deposited first and finer particles on top, all of which can happen during events like turbidity currents.
Grain size analysis is crucial in understanding the transportation and depositional history of sediment. For instance, clastic sedimentary rocks like sandstone with a high percentage of feldspar, known as arkose, suggest short transport due to the less durable nature of feldspar compared to quartz. Grain size becomes smaller the further from the source due to continual weathering and erosion. Finally, sediments undergo compaction and cementation, turning them into sedimentary rocks by reducing porosity and filling spaces with minerals acting as a glue.