When a river reaches a base level, its forward velocity rapidly decelerates as it enters a larger body of standing water and ________ is formed.
A) an estuary
B) an alluvial terrace
C) a delta
D) a stream terrace

Question

Quizplus · Accepted Answer

A river delta is formed as a river reaches its base level and enters a larger body of standing water, typically the ocean. The forward velocity of the river rapidly decelerates, causing the sediment carried by the river to settle and form a delta. Option A, an estuary, refers to the area where freshwater from a river meets and mixes with saltwater from the ocean, but it is not necessarily formed by a river reaching its base level. Option B, an alluvial terrace, refers to a flat area adjacent to a river that has been formed by the accumulation of sediment over time, but it is not necessarily formed when a river reaches its base level. Option D, a stream terrace, refers to a flat area that was once the floodplain of a river but has been uplifted and is now above the current level of the river. It is also not necessarily formed by a river reaching its base level.

When a River Reaches a Base Level, Its Forward Velocity