Final answer:
Deltas generally get bigger over time as rivers deposit sediment, but they can also shrink or erode under certain conditions such as reduced sediment supply or rising sea levels.
Step-by-step explanation:
A delta is a landform that occurs at the mouth of a river, where it meets a body of water like an ocean or a lake. Over time, deltas can change in size and shape due to various factors such as sediment deposition, erosion, and sea level changes. Generally, deltas tend to grow larger because rivers carry and deposit sediment as they flow towards the ocean or lake. However, some deltas can erode or shrink if there is a decrease in sediment supply or if the sea level rises at a faster rate than sediment deposition.
For example, the Mississippi River delta, located in the United States, has been growing in size over thousands of years. As the river flows towards the Gulf of Mexico, it carries large amounts of sediment from upstream. When the river reaches the ocean, the sediment settles and contributes to the growth of the delta. On the other hand, the Nile River delta, located in Egypt, has been experiencing some erosion and shrinkage due to decreased sediment supply and rising sea levels.
In summary, deltas generally get bigger over time as rivers deposit sediment, but they can also shrink or erode under certain conditions such as reduced sediment supply or rising sea levels.