What forms over time due to continuous lateral erosion by a meandering stream?

Over time, a meandering stream undergoes continuous lateral erosion, leading to the formation of a broad, flat valley floor. As the stream meanders, it erodes the outer banks more extensively than the inner banks, causing the valley to widen. This process broadens the valley floor, creating a relatively flat area that is often surrounded by higher terrain on either side. The sediment that the stream erodes from the banks can also contribute to this flat floor, along with the deposition of materials in slower-moving water areas.

The other options, while they pertain to erosion and landscape formation, do not accurately describe the typical result of continuous lateral erosion by a meander. Steep cliffs and deep gorges are typically associated with vertical erosion, which contrasts with the lateral erosion characteristic of meandering streams. Islands within the river may form due to sediment deposition in the stream but are not a direct product of the continuous lateral erosion process described by the question.