Final answer:
A meandering stream grows laterally due to erosion on the outer banks of bends and deposition on the inner banks. These processes result in the outward expansion of curves in the stream. Sediment transport is crucial in this evolution of stream morphology.
Step-by-step explanation:
The processes that work together to cause a meandering stream to grow laterally are erosion and deposition. As a meandering stream flows, the outer banks of bends experience erosion due to the faster flow of water which scours away the bank materials. On the inner banks of the bends, where the water flow is slower, there is deposition of sediments as the water lacks the energy to carry them. Over time, this erosion on the outer bends and deposition on inner bends cause the meandering curves of the stream to become more pronounced, leading to lateral growth of the stream.
Erosion is the process where soil and rock are removed from the Earth's surface by natural processes such as water flow, which then transport them away. In the context of stream evolution, sediment transport by the flowing water is a key aspect of erosion that shapes the river channels. Deposition occurs when these sediments are laid down in new locations once the water slows enough to drop its load, contributing to the stream's lateral expansion.